Podcasts about rtl sdr

Foundations of Amateur Radio Recently I started an experiment I plan to run for a year. Using a WSPR beacon and a dummy load I'm transmitting 200 mW, 24 hours a day across all bands supported by my hardware, in this case it covers 80m, 40m, 30m, 20m, 17m, 15m, 12m, and 10m. The aim of the experiment is to determine if, and to what extent my dummy load can be heard outside my shack. Why? Because I've not seen anyone do this and because a dummy load is widely believed to not radiate, despite evidence to the contrary. Together with the transmission side, I've also configured an RTL-SDR dongle, initially with the telescopic antenna it came with, now, since my HF antenna isn't being used by the beacon, I'm using it instead. It's about five metres away from the beacon, outside. It's a helically wound whip resonant on the 40m band built by Walter VK6BCP (SK). It's what I've been using as my main antenna for the past seven years or so. While I'm telling you this, my beacon has been heard by my dongle 1,182 times across all eight bands. Some of those reports were from inside the shack, some from outside, some while I was monitoring a single band, and for the past week or so, I've been monitoring all the bands supported by "rtlsdr_wsprd", 18 in all. Purposefully, this includes some bands that I'm not transmitting on, because who knows what kinds of harmonics I might discover? The receiver changes band every half hour, so over time when I monitor a band will shift across the day, this is deliberate. I don't know when a stray transmission might suddenly appear and this will give me the best chance of hearing it, short of using 18 different receivers. At this time, my beacon hasn't been heard by any other station. I'm not expecting it to, but that's why I'm doing this experiment in the first place. I'm not in any way reaching any sense of "DX on a dummy load", but it got me thinking. My beacon can be heard, albeit by me, from five meters away. So it's radiating to some extent. I've already discussed that this might come from the patch lead between the beacon and the dummy load, or it could be the dummy load itself, or some other aspect of the testing configuration. Regardless of the situation, there is a signal coming from my beacon that's wirelessly being heard by a receiver. That's the same as what you'd hope to achieve with any antenna. So, in what way are an antenna and a dummy load different, and in what way are they the same? Whenever someone asks this, the stock answer is that an antenna radiates and a dummy load doesn't. My experiment, 20 days in, has already proven that this distinction is incomplete, if not outright wrong. Even so, if we take it on face value, and we say, for argument's sake, that a dummy load doesn't radiate and an antenna does, then how do we materially distinguish between the two? How does an antenna compare to a dipole, Yagi or vertical antenna and where does the isotropic radiator fit in this? The best I've come up with so far is a spectrum line comparing the various elements. Let's say that at one end of the spectrum is a dummy load, at the other is an isotropic radiator, to refresh your memory, that's the ideal radiator, it radiates all RF energy in all directions equally. Somewhere between the two ends is a dipole. We might argue if the dipole sits equally between a dummy load and an isotropic radiator, but where does a Yagi or a vertical fit in relation to the dipole? Also, if you turn a Yagi in the other direction, does it change place? So, perfect this notion is not, but here's my question. What's the measurement along the axis between the dummy load and the isotropic radiator? It's not SWR, since the ideal antenna and a dummy load share the same SWR, unless this line is a circle that I don't know about. It might be Total Radiated Power expressed in Watts, but that seems counter intuitive. It would mean that in order to determine the effectiveness of an antenna we'd need to set-up in an anechoic chamber, basically a warehouse sized room where incoming radiation is shielded to some predetermined standard. Do we measure gain using a VNA and call it a day, or is there something else going on? Remember, we're attempting to quantify the difference between a dummy load and an antenna. In case you're wondering, I'm asking the question. In the 15 years I've been part of this community, I've never seen any coherent response. The Internet seems to return a variation on the radiation vs. not-radiation pattern, but so far I've not seen anyone quantify this, or perhaps I haven't understood it while it was staring me in the face. I even checked the syllabus for the three license classes in Australia. The single reference that the regulator appears to specify is that at the introductory level you are required to, wait for it, recall that when testing a transmitter, a non-radiating load, or dummy load, is commonly used to prevent a signal from being radiated. Very illuminating. Obviously my dummy load is of the wrong type, the radiating variety. Which begs the question, if there's an ideal radiator, is there a theoretical ideal dummy load that doesn't radiate in any way, and if so, how far away on this line is it from my actual dummy load? Over to you. What are your thoughts on this? Better yet, got any references? I'm Onno VK6FLAB

How do we handle scope creep for vulnerabilities?, find the bugs before it hits the real world, risk or hype vulnerabilities, RTL-SDR in a browser, using AI to hack AI and protect AI, 73 vulnerabilities of which 0 patches have been issued, Spinning Cats, bypassing WDAC with Teams and JavaScript, Rust will solve all the security problems, did you hear some Signal chats were leaked?, ingress nginx, robot dogs, what happens to your 23andme data?, Oracle's cloud was hacked, despite what Oracle PR says, inside the SCIF, and cvemap to the rescue. Visit https://www.securityweekly.com/psw for all the latest episodes! Show Notes: https://securityweekly.com/psw-867

How do we handle scope creep for vulnerabilities?, find the bugs before it hits the real world, risk or hype vulnerabilities, RTL-SDR in a browser, using AI to hack AI and protect AI, 73 vulnerabilities of which 0 patches have been issued, Spinning Cats, bypassing WDAC with Teams and JavaScript, Rust will solve all the security problems, did you hear some Signal chats were leaked?, ingress nginx, robot dogs, what happens to your 23andme data?, Oracle's cloud was hacked, despite what Oracle PR says, inside the SCIF, and cvemap to the rescue. Show Notes: https://securityweekly.com/psw-867

How do we handle scope creep for vulnerabilities?, find the bugs before it hits the real world, risk or hype vulnerabilities, RTL-SDR in a browser, using AI to hack AI and protect AI, 73 vulnerabilities of which 0 patches have been issued, Spinning Cats, bypassing WDAC with Teams and JavaScript, Rust will solve all the security problems, did you hear some Signal chats were leaked?, ingress nginx, robot dogs, what happens to your 23andme data?, Oracle's cloud was hacked, despite what Oracle PR says, inside the SCIF, and cvemap to the rescue. Visit https://www.securityweekly.com/psw for all the latest episodes! Show Notes: https://securityweekly.com/psw-867

How do we handle scope creep for vulnerabilities?, find the bugs before it hits the real world, risk or hype vulnerabilities, RTL-SDR in a browser, using AI to hack AI and protect AI, 73 vulnerabilities of which 0 patches have been issued, Spinning Cats, bypassing WDAC with Teams and JavaScript, Rust will solve all the security problems, did you hear some Signal chats were leaked?, ingress nginx, robot dogs, what happens to your 23andme data?, Oracle's cloud was hacked, despite what Oracle PR says, inside the SCIF, and cvemap to the rescue. Show Notes: https://securityweekly.com/psw-867

Foundations of Amateur Radio Recently I received a question in relation to the Bald Yak project. If you're not familiar, "The Bald Yak project aims to create a modular, bidirectional and distributed signal processing and control system that leverages GNU Radio." I know that I've said that several times now and I suspect I'm going to say it several more times before we're done. I was asked about a specific radio and if this project could make it use a frequency that the supplied software didn't cover. The answer is deceptively simple and if you know me at all, you know what's coming: "It depends". As with many things, what it depends on is not fixed. I'll come back to the question, but I'm making a diversion past a magical place, the local hardware store. You can buy everything you need to build a house with the caveat that some assembly is required. GNU Radio is similar for building a signal processing system, but, wait for it, some assembly is required. In the context of GNU Radio this means that you'll need to collect all the bits and wire them together, fortunately you're unlikely to need Personal Protective Equipment or access to a First Aid Kit, unless of course the idea of playing with computers gives you palpitations, in which case I'd recommend that you go see your doctor. One of the less obvious things you'll come across with GNU Radio is how to bring signal processing into the physical realm, in other words, how do you get a signal into your computer, known as a "source", and get it out, called a "sink". The ability to talk to physical hardware arrives in roughly three different ways. Let's call them, "native", "library", and "abstraction". Native access requires that GNU Radio already knows about the hardware out of the box. Library access requires that the hardware manufacturer has provided software libraries, also known as drivers, allowing GNU Radio to communicate, and finally, abstraction is where a third party has written a library that knows how to talk to hardware from different manufacturers. The distinction between these is almost arbitrary, for example abstraction might require a driver from a hardware manufacturer. Similarly, because all this software is open source, native can include software from other projects, like the RTL-SDR blocks from Osmocom, Open Source Mobile Communications, and UHD blocks written by Ettus Research, which in turn can be seen as an abstraction. As I said, some assembly required. I will point out that this provides a great deal of flexibility, albeit at the cost of complexity, there's still no such thing as a free lunch. At this point you might shake your head and run away. I get that, it can be daunting. Before you do, consider the scenario where you have a working system and you upgrade your hardware. In a GNU Radio world you'll need to figure out how to configure the new hardware and then all your other stuff will continue to work. The alternative is upgrading each of your applications to connect to your new radio and in doing so, run the risk of making your old radio obsolete, even if you are collecting them .. let's say for posterity rather than hoarding .. because radio amateurs never hoard anything .. right? Back to the original question. Can GNU Radio make a radio use frequencies that the software that came with the radio cannot? As I said, "it depends". First of all, the hardware needs to actually be able to support the frequency. Then someone needs to have written a library to use that frequency, then GNU Radio needs to be able to use that library. That said, the chances of that happening are much higher than the chance of the hardware manufacturer rolling out this feature within your lifetime. Before you start yelling at me, yes, this is manufacturer dependent, some provide open source tools, many still don't. There are alternative ways to access different frequencies. The PlutoSDR is a computer and radio in a box. You can connect to it, change some settings and have it access a whole lot more frequencies. In some ways it's like adding or removing jumpers on a traditional circuit-board. Another approach is to use an up- or down-converter. Essentially a piece of hardware connected between antenna and radio that translates frequencies to different bands. A down-converter allows you to use the 23cm band on a radio that's only capable of 70cm. Similarly, an up-converter allows your 70cm radio to hear HF signals. If you see a symmetry here, you didn't imagine it. You need both to transmit and receive, sold together in the same box as a transverter. Just so we're clear, the radio is still using the 70cm band, but the RF coming in and out of the antenna connected to the transverter is on a different band entirely. It's why my Yaesu FT-857d has three menu options, 89, 90 and 91, to adjust the display to show the actual RF frequency. As an aside, you could use this functionality if your radio is off frequency by a known amount. As I've said before, GNU Radio is a powerful tool. It contains many different moving parts, the system is complex and unwieldy, but with it comes the promise of doing some amazing stuff. The whole point of the Bald Yak project is to make this all accessible to the wider amateur community, not just computer geeks and software radio nerds. If you have questions, feel free to drop me a line. I'm Onno VK6FLAB

Foundations of Amateur Radio Recently I received a lovely email from Michele IU4TBF asking some pertinent questions about the Bald Yak project. If you're unfamiliar, the Bald Yak project aims to create a modular, bidirectional and distributed signal processing and control system that leverages GNU Radio. The short answer to how I'm doing getting GNU Radio to play nice with my computer is that I have bruises on my forehead from banging my head against the wall. When I get to success I'll document it. To be clear, I'm not sure what the root cause is. I suspect it lies between the GNU Radio developers, the people making packages and the manufacturer of my computer. I'm the lucky one stuck in the middle. A more interesting question that Michele asked was, for Bald Yak, what is the A/D and D/A requirement for making GNU Radio talk to an antenna? This is a much deeper question that meets the eye and I think it serves as a way to discuss what I think that this project looks like. Ultimately in the digital realm, to receive, an analogue antenna signal needs to be converted to digital using an Analogue to Digital or A/D converter, and to transmit, the reverse uses a Digital to Analogue or D/A converter to make an electrical signal appear on your antenna. The specific A/D or D/A converter determines what you can do. The sampling rate of such a converter determines what frequencies it can handle, the sample size determines the range of signals it can handle. You can compare it with a video screen. The sample rate determines how many pixels on the screen, the sample size determines how many colours in each pixel. The sample rate of an A/D converter is measured in samples per second. If the device only has one channel, you could think of this as Hertz, but if there are multiple channels, like say a sound-card, the sample rate is likely equally divided across each channel. You might have a sound card capable of 384 thousand samples per second, or kilo-samples, but if it supports simultaneous stereo audio input and output, only 96 of those 384 kilo-samples will be allocated to each channel and only half of those will actually help reconstruct the audio signal, leaving you with 48 kHz audio. In other words, the advertised frequency response might not have a direct and obvious relationship with the sample rate. At the moment I have access to a few different A/D and D/A converters. The simplest one, a USB audio sound card, appears to do up to 192 kilo-samples at 16 bits. The next one, an RTL-SDR tops out at a theoretical rate of 3.2 million or mega-samples at 8 bits. The Analog Devices ADALM-PLUTO, or PlutoSDR handles 61.44 mega-samples at 12 bits. Now, to be clear, there are other limitations and considerations which I'm skipping over. Consider for example the speed at which each of these devices can talk to a computer, in this case over USB. I'm also going to ignore things like mixers, allowing devices like the RTL-SDR and PlutoSDR to tune across frequency ranges that go beyond their sample rate. Each of these three devices can convert an analogue antenna signal into bits that can be processed by GNU Radio. All of them can also be used to do the opposite and transmit. Yes, you heard me, several amateurs figured out that an RTL-SDR can actually transmit. Credit to Ismo OH2FTG, Tatu OH2EAT, and Oscar IK1XPV. The point being that whatever Bald Yak looks like, it will need to handle a range of A/D and D/A converters. As I've said previously, I'm aiming for this to work incrementally for everyone. This means that if you have a sound card in your computer or an $8 USB one, this should work and if you have an $33,000 NI Ettus USRP X410 lying around, this too should work. Also, if you have an X410 lying around not doing anything, I'd be happy to put it to use, you know, for testing. So, kidding aside, what about the rest of the Bald Yak experience? GNU Radio works with things called blocks. Essentially little programs that take data, do something to it, then output it in some way. It follows the Unix philosophy, make each program do one thing well, expect the output of every program to become the input to another, design and build software to be tried early and use tools rather than unskilled labour. Amateur radio transceivers traditionally use electronics blocks, but if we move to software, we can update and expand our capabilities as the computer we're using gets faster and the GNU Radio blocks evolve, and because it's all digital the computer doesn't actually have to be in the same box, let alone the same room, it could be in multiple boxes scattered around the Internet. So, the idea of Bald Yak is a collection of blocks that allow you to do radio things. You might have a separate box for each amateur radio mode, AM, FM, SSB, RTTY, CW, WSPR, FT8, FT4, Q65, but also modes like Olivia, FreeDV, SSTV, Packet, PSK31 or Thor. Instead of having to figure out how to wire these modes into your radio and your computer, the infrastructure is already there and you just download another block for a mode you want to play with. We'll need to deal with variables like which A/D and D/A converter is being used and what their limitations are. We'll also need to build a command and control layer and probably a few other things. I'm considering a few other aspects. For example, GNU Radio is mostly run with text files. We might distribute those using something like a web store. GNU Radio is proving hard to install, perhaps a LiveCD is the way to go. We'll need to come up with a base level of functionality and the documentation to go with it. I'm still contemplating how to best licence this all, specifically to stop it from being exploited. Feel free to get in touch if you have ideas. I'm Onno VK6FLAB

Foundations of Amateur Radio Recently I built a first attempt at a noise cancelling circuit, on my couch, in GNU Radio, without holding a soldering iron and running the risk of the room smelling like burnt chicken, because if you believe the Internet, sometimes holding a hot piece of metal by the hot end is not the best way. The idea behind the circuit, or more accurately, flowgraph, is that you take a signal from two sources, invert one, combine them, and they cancel each other out. If the signal with the noise only contains noise, then you can, at least theoretically, remove the noise from the actual signal. Before you think that I'm inventing something new, I'm not. I'm merely attempting to recreate the same notion I came across decades ago, where you combine the signals from two microphones, preferably identical, reversing the wiring in one and talking into a microphone whilst holding the other one away from your mouth. I did essentially the same thing using RF signals from two RTL-SDR dongles. Randall VK6WR pointed out that, aside from misusing the word "mix", which in electronics really means multiply, but in audio means combine, Randall suggested I use "add" and "subtract". I'm still working out how best to name things, because we're talking about audio and RF, sometimes at the same time. Perhaps that's where I went wrong. I'm currently using "combine" as my technology neutral word, but I'm happy to take suggestions. All that was the side show, because as Randall points out, doing this in RF is much harder than in audio. This is already something I knew. At the time I didn't really know how to get two different but the same sources of audio to experiment with, so I started in the deep end at the RTL-SDR dongle side. Now, armed with the encouragement from Randall I built a horrible thing, which is easy when you just drag and drop blocks on a screen. I built two independent FM decoders that use the exact same parameters, so they're tuned to the same frequency, they're amplified and tweaked identically. The only difference is that they each decode a different dongle. I then piped each of those into my magic noise cancelling circuit and tried again. Aside from dealing with hardware restrictions, causing things like buffer under-, and over-run, that's when the computer isn't processing all your samples, or is getting ahead of itself and is running out of samples, I can make audio come out of the speaker in my computer. I can prove that there are two signals, by setting the amplification of either to zero, and still get sound from the other source, however, noise cancelling, no matter what I tried, didn't work. Then I decided to simplify, rather than trying to cancel out "the Heat is on", word of honour, I'm not making that up, that's the song that was playing, I went back to basics starting with a tone. I fed the same tone into the noise cancelling block twice, once as signal, once as noise. Magic, the cancelling works. I also learned that changing the frequency of the noise and changing it back gets you into all kinds of problems and even if you send the same tone, one shifted in phase by a known amount, getting the two to cancel each other out is non-trivial. You might think that this was all a complete waste of time and if you're just driving past it looks like a swollen electrolytic capacitor about to burst your bubble, but it's not that bad. Here's what I learned from this little adventure. I can make hierarchical blocks out of flowgraphs. This is important because at some point all the functionality associated with Bald Yak will likely end up being implemented like this. I also learned that such a block can contain user interface elements, which means that we can build blocks that know how to do stuff and tweak how they operate without having to build a user interface every time we use such a block. I learned that we can implement an idea that would be hard using physical components and test it really quickly, in this case my available time was the limiting factor, not the testing. If I'd done this with components I'd still be trying to figure out where to get them from, let alone turn up the heat. Another bonus is that I didn't spend a single dime and I can dispose of it with the click of a button, rather than trying to figure out how to recycle components and circuit boards. I also learned that the idea as I built it doesn't work quite as I expected and that things that I didn't anticipate, like changing the frequency, buffer under-, and over-runs, impacted my efforts in unexpected ways. There's a delay between making a change on the user interface and the effect becoming audible, and I learned I can make a dongle work on my computer and that installing GNU Radio is a challenge at the best of times. In other words, even though I'm unlikely to use the noise cancelling efforts in their current form, there was plenty I learned from the experience. From my perspective, this was a success. What have you experimented with and learned? On a completely unrelated matter, long overdue, and music to the ears of some, can you spell SKCC, I've finally put all the Morse Code versions of my podcast on a thumb drive and plugged it into my car. During the week I've managed to listen to about two hours of Morse. While I don't know most of the letters of the alphabet, I can still detect letter and word boundaries. I'm Onno VK6FLAB

Foundations of Amateur Radio The other day I was sitting on the couch lounging about when I came up with an idea and there and then I picked up a circuit board, soldered down a hundred or so components and built a noise cancelling gadget, all within about an hour .. right there, on my couch. Yeah, that didn't happen, least of all, my soldering skills are not up to scratch, never mind the couch. I did however build a noise cancelling circuit, on my couch, in about an hour, but no soldering iron was hurt and the room didn't smell of chicken afterwards. Instead I used GNU Radio to put together a series of blocks that allow me to apply noise cancelling to a signal. How does this work? Well, imagine a signal mixed together with the negative version of that signal, think of it as swapping positive and negative if you like. If you mix two identical signals together, one of them inverted, you end up with nothing, because they cancel each other out, where one is high, the other is opposite and low and vice versa. Mix a high signal with a low signal, you end up half-way. If they're the same but opposite, half-way is zero. Hearing nothing is not helpful, but what if the two signals were slightly different, let's say, one is connected to a proper 10m antenna and the other is connected to an antenna that picks up local noise. We'll call the antenna on 10m the "signal" and the local noise antenna the "noise". If you mix these together, you end up with a signal and noise combined, but if you invert the noise signal, you can, at least theoretically, filter out the noise that's common to both antennas. Now I did say "theoretically" and that's because while it sounds simple, it's far from it. Unless you have a special radio, the two signals are not coming from the same device and won't really be identical where it matters. For example, let's call it the volume or gain of one might be higher than the other. One might arrive slightly later than the other if the coax isn't the same length or the electronics in both radios are different. There are other things too, but let's just stay with this for a moment. You could amplify or attenuate one or both signals to make them the same or similar levels. You could change the phase, think of it as the time when a signal starts, and synchronise the two signals in time manually. Of course whilst you're doing this, inside GNU Radio, the computer is doing some serious math, which takes time to make these changes, which introduces further delays you'll also need to account for. Building it was simple. Testing it much less so. After coming to grips with the USB port on my computer, which for reasons best known to the manufacturer, cough, Apple, switches off ports that are in use, I managed to get two RTL-SDR dongles connected and working. This involved removing GNU Radio, which was installed using a tool called "homebrew", then installing it instead using "radioconda", twice, since the first time the installer failed with an error, actually three times, because the failed installation left all manner of rubbish behind, so that needed to be removed; then I had to disconnect my keyboard and track pad, because for reasons only known to the manufacturer, yeah, the same one, they won't play nice if there's an RTL-SDR dongle plugged into the USB-C hub, I finally got this running, which in turn involved figuring out what the GNU Radio "Device Arguments" look like for a locally connected dongle, in case you're wondering, it's "rtl=0" for the first one and "rtl=1" for the second. Clearly this project is living up to its name, Bald Yak. Now I can invert a signal, I can amplify and attenuate it, change the phase, shift the frequency, swap the I and Q, do a complex conjugate, and have a user interface that can change these settings as required. I'm going to ignore the hour of my life I'm not getting back to understand how variables, parameters and user interface items hang together and how they interact. It's logical, but it takes a bit to wrap your head around it and I'm a software developer, so I don't envy you if you're not. Anyway, I tuned to a local FM broadcast radio station and couldn't make any noise go away. I then discovered that my noise antenna was picking up the station just fine, so that didn't help. Then I swapped radios, actually, I just swapped the zero and the one in the "Device Argument" fields and tried again. In the process I discovered how you can create a so-called "Hierarchical Block" in GNU Radio and to my delight also discovered that there is one that can have a user interface, so I can make a stand-alone block, that has a user interface, that I can use in another project, which is how I intend Bald Yak to function. So, changing stations, I could finally hear noise, but still no reduction. Then I realised that I was using FM, not single side band, so I started hunting for an SSB decoder but had to abandon ship to go and do life. Overnight I realised that if everything went to plan, the two FM signals should have cancelled each other out, making silence, which they didn't, despite my efforts. So, at this point I have a thing that can alter noise and mix it with a signal for the purposes of noise reduction. That it doesn't work is potentially because I have not enough range in my adjustments, or too much range with not enough steps, just as likely it's because I'm missing some fundamental understanding somewhere. If you have any documentation I should read, please don't be shy. As life adventures go, I'm hooked, but it's not without shaving Yaks, Bald or otherwise. I'm Onno VK6FLAB

Foundations of Amateur Radio For quite some time I have operated a WSPR or Weak Signal Propagation Reporter beacon on the 10m band. If you're not familiar with it, I've dialled the power right down to 10 dBm, or 10 milliwatts. You'd think that this would be a fool's errand, but it was heard 13,945 kilometres away. Of late the reports have been far and few between, despite the 10m band being quite active. Encouraged by a friend playing on 15m, I made the decision to change bands. At the moment this is not a trivial process, though at some point in the not too distant future, hopefully before I need a Zimmer Frame, I intend to erect a multi-band Hustler 6-BTV antenna that has been in storage for several years. Before that occurs, since it involves all kinds of shenanigans, I went for a simpler option, replace the 40m helical whip antenna with a 15m helical whip, something I can do without climbing on the roof. In case you're wondering, using an SG-237 antenna coupler, the 40m antenna tunes fine on 10m, but not so much on 15m. After pulling the replacement antenna from its hidey-hole I discovered that it was missing a tip. I don't recall if it ever had one, it came from the estate of a fellow amateur, Walter VK6BCP (SK). I took it on faith that it worked on the band that it was labelled with and went looking for a way to close off the tip. In the end I used heat shrink with a glue lining and sealed it off, folded over the tip and used more heat shrink to keep it folded over. We'll see how well that works. I then unscrewed the 40m antenna from its mount and was frustrated that it would only come with the spring attached. Using a crescent and a pipe wrench I was able to unscrew the spring but discovered that the threaded stud that connects the two didn't stay in the antenna, instead it stayed in the spring, which meant that I couldn't attach my 15m antenna without breaking something. I remembered that I had another spring lying around, so I dug that out of storage, I really need to set-up a "part-db" to keep track of where everything is, and attached the 15m antenna to the spring and screwed it back into the antenna mount and I'm back in business. In putting away the 40m antenna I lifted it up after removing the spring and promptly got wet. Litres of brown water came pouring out of the antenna. It turns out that the adjustable tip isn't sealed and sitting on my roof for several years managed to fill it full of water, that's through a tiny opening at the tip, in a country known for hot and dry, it's expected to be 40 degrees Celsius here today. It made me wonder if that water was why the beacon wasn't heard recently. The next step involved changing the beacon frequency. The hardware is a ZachTek 80To10 desktop transmitter, built by Harry, SM7PNV. The software to change settings runs on Windows and since my system crash in June last year I've not had any Windows machines lying around. I went to the ZachTek website and discovered in the downloads section that there is a link to a web page configuration tool written by Phil VK7JJ, of wspr.rocks fame, that allows you to open a website, plug in your beacon, and configure it from any Chrome web browser. I was both astonished and delighted that this exists. I changed the beacon band from 10m to 15m and powered it up. One final step. As I said, for the last little while my beacon has only sporadically been heard, so I set up a local monitoring system. It consists of a little computer connected to an RTL-SDR v3 dongle and the included telescopic dipole. Using a Docker container written by Guenael VA2GKA, I monitor my own beacon. After updating the band from 10m to 15m, reports started flowing in. As an aside, the last time I did this I built a custom Raspberry Pi image and had to change several things to start monitoring after a reboot. This time I used an inbuilt Docker mechanism, "restart unless stopped", to launch the container. This means I don't need to alter the system and I can add and remove containers as I need to. This is important because it's likely how some of the "Bald Yak" project will also gain functionality. I'm feeling rather chuffed that on my first day back as a human after recovering from my first bout of COVID, I managed to move my beacon to 15m, get it on-air, configured and transmitting with confirmation in the log. The only thing missing now is your signal report. I'm Onno VK6FLAB

Foundations of Amateur Radio Thirteen years ago I opened my mouth to express my thoughts on what to do with an amateur license after hearing an operator complain they needed more power to talk to a station across 600 kilometres, whilst I used the same 10 Watts to communicate with a station nearly 15,000 kilometres away. In all, I've shared my thoughts some 700 times, documenting my journey though this majestic hobby, describing what I've been up to, reporting my successes and failures, sharing my observations and making recommendations. I've built projects and attempted to start new processes, I've encouraged, cajoled, on occasion berated or applauded as I found it. Throughout the experience I've attempted to build this wonderful community, to inspire and to grow it. Sometimes I might even have succeeded. I could not have done this without you. So, thank you. If I haven't mentioned your name or responded to your email, it's not because I didn't see your contribution. You have delighted me and lifted me up and I thank you for sharing your thoughts. At this point you might wonder if I'm hanging up my microphone and to that I say: No, not even close. Instead I'm continuing with this experiment, rough and ready though it is. It occurs to me that over the years I've started a great many projects and documented them as they happened, either here, or on my vk6flab.com website, or on GitHub. These projects take time and effort that go beyond what you encounter here. Sometimes it's hours, sometimes it's weeks. Recently a lot of my musings have been about things I've wanted to do, rather than describing things that I've done. Mind you, not for lack of desire. I want to try something different. I'm going to, at least for the next little while, bring you along with a project as I'm building it. No doubt I'll get distracted by squirrels along the way, but I'm going to attempt to build something for us as a community, for amateur radio, because I want to actually do something, rather than talk about it and I need to manage my limited resources and this way I get to build something and you get to have me sharing my thoughts. From my perspective, win-win. So, let's dive in. Amateur radio is a hobby that takes all kinds. A lot of activity is curtailed by money, or rather, lack of money. That doesn't have to be the case and I think I can show you how. That's not to say that this is going to cost nothing, but you can likely start with what you already have and work your way up as your budget allows, rather than require a significant outlay just to get your toes wet. Over the past few weeks I've been talking about a toolkit called GNU Radio. It can be used to build systems that can process data, like say radio signals which come in all shapes and sizes. You can start by connecting an antenna to a sound card and use that as a radio tuner. You can also use a sound card as a way to listen to signals coming in via the Internet, or a radio you might already own. Sound cards exist in most computers but can be purchased for around $10. If you want to handle more data, you can spend $50 and use an RTL-SDR dongle. This incremental path continues. You can build a digital radio, or buy a learning kit, or something else, all the while still being part of the same ecosystem. I want to build a system where you can experiment with radio without needing to buy new hardware every time you want to try something new. I want it to work with a sound card as well as with the latest $7,000 radio you can get shipped to your door. I want to do this in such a way that we can start to embrace all that is possible within the realm of software. Ultimately I want to be able to use any signal source anywhere and GNU Radio seems ideally suited as the tool for the job. I envisage that we'll build a distributed system, where signal processing and the signal itself don't have to be in the same spot, which is useful for a whole host of reasons, even though it increases the level of complexity by at least an order of magnitude. This isn't going to be easy. It's not going to be working tomorrow, perhaps not even a year from now and as long as new radios are invented, it will never stop, but we'll see how it goes. For example, I spent a week attempting to install GNU Radio on my Macintosh, asked two expert groups and got nowhere. In stark contrast, I installed it on my Linux Debian workstation and the example I tried worked out of the box. In other words, plenty of obstacles to overcome. Before I go, I'll make this explicit. I want this to be open source, so anyone can play. I haven't yet decided on which specific license to use, but I'm cognisant that there are many large companies making obscene amounts of money from the volunteer efforts of the open source community and as one of the volunteers, I'd like to be able to pay for food and a roof over my head. I expect and appreciate your feedback, so don't be shy. I'm Onno VK6FLAB

Foundations of Amateur Radio The hobby of amateur radio is one of experimentation and change. For decades this came in the form of circuit diagrams, components and scrounged hardware from anything that wasn't bolted down. New functionality came with the aid of a soldering iron. More recently, functionality comes from participation in the global electronics market where you can buy any radio you like and have it shipped to your door within hours at an unbeatable price. Mind you, buying all those unbelievably cheap radios does start adding up and if you want to use more sophisticated hardware, that too is possible, at a price, somewhere between $50 and a new Porsche. Whilst that's an option for some, for the rest of us, there are better and cheaper ways. Of course it doesn't stop there. If you connect any radio to a computer, you can use whatever software you like to encode and decode any signal you can imagine. With a traditional radio connected to a computer you can make it participate in hundreds of different so-called digital modes. Before I continue, let's look at radio in a slightly different way. Consider an antenna as a continuous source of voltages that are amplified, filtered and demodulated in some way by a radio. You can think of the combination of antenna, radio and computer as a stream decoder. To decode a signal in a new way requires a new decoder, which you could build from components or as I've said, buy online. During the week I've continued experimenting with GNU Radio. If you're unfamiliar, it's a toolkit that allows you to build so-called flow graphs that can process a signal stream. Think of it as a box of Lego that you can put together to build any type of decoder. Let me say that again. Imagine that you want to decode or transmit a mode like FreeDV, M17, APRS, Olivia, Contestia, or Hellschreiber. With the GNU Radio toolkit, all of this is possible and you won't need to buy new hardware or bust out the soldering iron every time you want to experiment with a new mode. If you have been playing with digital modes already, you'll likely point out that you can already do this today by using software running on a computer, and that's true. What that doesn't tell you is that this comes with a very specific limitation, namely that all those modes require that they fit inside a single audio channel because all those digital modes you might be familiar with are essentially using an SSB or FM signal with the audio generated or decoded by a computer. Even if you have a modern radio like for example an ICOM IC-7300, you'll still be limited in what modes of transmission you can make. ICOM limits the transmit bandwidth to 2.9 kHz. Flex Radio appears to double that to 7.9 kHz, but numbers are sketchy. The point remains, most current amateur radio technology is based around the notion that a mode essentially fits within a single audio channel and a very narrow one at that. So, why does this matter? If you run out of FT8 space on a band, right now you need to change to an alternate frequency to play, but you'll only be able to see the stations that are using the same alternate frequency, as long as they fit within the bandwidth of an audio signal. If you wanted to check out the main frequency, you'd have to change frequencies and keep switching back and forth. Using this idea, monitoring all of FT4, FT8, WSPR and all CW beacons, all at the same time becomes unimaginable, not to mention costly if you needed a radio for each band and each mode. What if you wanted to use another mode that took more than about 4 kHz, like say a 5 MHz wide DVB-T signal which you could be experimenting with on 70cm? Or, what if you'd like to compare a repeater input with its output at the same time? Or compare two repeaters together? Or find the best band to operate on right now? The point being, that there are things that simply don't fit within a single audio channel that you won't be able to play with using a traditional radio. As it happens, that too is a solved problem. Remember that I mentioned that you can think of an antenna, radio, and computer combination as a stream decoder? What if I told you that an SDR, a Software Defined Radio, is essentially a device that translates antenna voltages into numbers which you can process with GNU Radio? Whilst that does imply replacing your radio, you don't have to jump in at the deep end to start playing and even if you do decide to buy new hardware, you can get your toes wet with all manner of self build or commercial kits. Even better, you can start with the gear you already have today and become familiar with GNU Radio and when you're ready to expand your station, you can add in an SDR and continue to use the same tools to experiment. Not only that, you can do interesting things by combining what you already have. Consider for example the idea of using an RTL-SDR as the receiver with a traditional radio as the transmitter. You could decode all of the FT8 signals on a band and transmit where there was space to do so. The point being that you can do this one step at a time. Every time you download or build another GNU Radio flow graph, you can have a new decoder and as time goes on, you'll be able to decide what hardware you might want to pair it with. To be clear, I'm talking about the gradual change from component based radio using audio interfaces into software based radio. It's not like we haven't done this before. Anyone recall spark gaps, or valves? The future of experimentation is bright and it's filled with bits. I'm Onno VK6FLAB

Foundations of Amateur Radio Over the past weeks, actually, probably more accurately years, I've been carrying around an idea. It's been bubbling away and I've been trying very hard to make it solidify into something that I could explain and then hopefully attack. Today I woke up with a hunger to do some radio and ultimately tell you about it. To get to a point where my Aha! moment emerged, I need to provide some history. Traditional radio activities involve variations on a radio plugged into an antenna with the operator talking into a microphone or torturing a Morse key. If you want to operate digital modes, you essentially have two choices. You can use a rare radio with in-built digital modes or, more commonly, connect a computer to the radio via an audio interface, which essentially replaces the operator with a computer. This implies that the radio is physically connected to the computer and in the same room. What if you don't want either? There's another aspect to this. Modern SDRs or software defined radios, tend to use the network to get information from the antenna to the user. The network can transport the radio signal, but also control signals, to change things like frequency and mode, and if the radio supports it, bands, antennas and other fun stuff like filters. There are ways to control a traditional radio across the network with so-called CAT commands, or Computer Assisted Tuning. This same technology can be used to connect a logging tool, so it knows what frequency and mode to log when you make a contact. What CAT control lacks is audio. Said differently, although some solutions exist to send Morse code, you cannot use CAT to listen to the radio, or speak into a microphone. This isn't an issue if the radio and you are in the same room, but if they're not, then things get tricky. And as a final piece of background information, a traditional radio is based around audio, that is, the information going between you and the radio, or a computer and the radio, is limited to audio. This represents about 4 kHz of signal. In other words, if you're tuned to 28.500 MHz, then a traditional radio can "hear" the radio signal between 28.500 and 28.504 MHz, sufficient for a single audio signal, but even a simple digital radio, a $50 RTL-SDR using a USB cable, can handle 2.4 MHz, plenty to cover all of the 10m band between 28.0 and 29.7 MHz with room to spare. I've been looking for something, anything, that brings these two vastly different worlds together for a number of reasons. I've spoken previously about some of these. For example, I do not want to physically connect my traditional radio, a Yaesu FT-857d, to my computer because I do not want to have the potential of stray RF coming into my computer. I'd also love to be able to run the same decoding and control tools for various radios, the Pluto SDR, several RTL-SDR dongles, my 857 and other radios as they come into my shack from time-to-time. Then there's the signal processing side of things. I'd love to be able to learn how to decode Morse and eventually other modes using a computer. I also want to be able to use a voice-keyer during a contest so the whole house doesn't ring from the sound of me calling CQ Contest, or CQ DX for hours on end. I've been making inroads into this. I managed to get rigctld to work across the network using Docker containers at both ends. I attempted to get audio working, but that has so far been a dismal failure, despite assistance on several fronts. This morning I stumbled on the idea of using "GNU Radio" for both. I even came across some examples where two so-called "flow-graphs" can talk to each other across the network. Now at this point you're either going to be nodding your head, or you're going to be asking yourself what gibberish I just spouted. If you're already nodding your head, stand-by, if not, GNU Radio is a software toolkit that provides signal processing blocks that you can link together to create simple or sophisticated systems to manipulate signals, like those that come from radios, or radio telescopes, or mobile phone base stations, radar, ADS-B, or whatever else you can imagine. It's widely used in academia, government, industry, research, and of course by us, hobbyists. A collection of blocks and links is called a flow-graph and in essence it's a program or if you like, an App, that you can run. It comes with a tonne of examples and tutorials, including one where one flow-graph can manipulate another, either on the same computer, or somewhere on the Internet. What this means is that you could build a flow-graph that can talk to a Yaesu FT-857d and one that can talk to a Pluto SDR, or an RTL-SDR, or any other radio, and use that to talk to a flow-graph that understands how to deal with audio, CAT and anything else you might want to. It means that for the first time in years I can at least imagine a unified world where my 857 isn't a boat anchor when compared to my Pluto SDR. Of course they don't have the same functionality, but at least I can handle their signals in the same way. Unlike the path I was previously on, where I was attempting to cobble together several tools whilst attempting to avoid a headache from banging my head against the wall, today I can use one toolkit to build Apps that run on pretty much anything with a CPU and see the fruits of my labour. I'm working on a proof of concept and when I've got it to show-and-tell, I'll put it up on my GitHub page, cunningly named after me, VK6FLAB. A final observation. Amateur radio means different things to different people at different times. For me, today, it's about software and GNU Radio. Tomorrow it is just as likely to be about something else. What is possible depends entirely on your imagination, so get playing, either on-air, or on-line, whatever gets you smiling and remember, the impossible happens immediately, miracles take a little longer. I'm Onno VK6FLAB

Episode 0x7A 4-peat 4-peat! Turns out this is actually habit forming. The weekly venting/ranting is excellent for the spirit! Hope you're able to vent as well. Feel free to scream while listening - it's not weird at all. Upcoming this week... Lots of News Breaches SCADA / Cyber, cyber... etc. finishing it off with DERPs/Mailbag (or Deep Dive) And there are weekly Briefs - no arguing or discussion allowed And if you've got commentary, please sent it to mailbag@liquidmatrix.org for us to check out. DISCLAIMER: It's not that explicit, but you may want to use headphones if you're at work. ADDITIONAL DISCLAIMER: In case it is unclear, this is the story of (approximately) 5 opinionated infosec pros who have sufficient opinions of their own they don't need to speak for anyone except themselves. Ok? Good. In this episode: News and Commentary Biden bans Kaspersky - effective July 20. FINALLY. Stolen test data and NHS numbers published by hospital hackers  Information is beautiful - World's Biggest Data Breaches & Hacks Breaches The City of Hamilton breach continues. It's a farce. My property tax dollars going to no good purpose at all. Ongoing since Feb 25, no sign that they're any closer to getting the majority of systems up and running - and $5 million out of the door. Sigh.   The number of systems remaining offline is incredible. I'm pretty sure I could put together a crack team of 5 who could spend evenings and weekends for less than a month to knock out all of this list without extending our recruiting pool past Hamilton and Burlington. Sheesh. Car Dealerships Nationwide Hit by Massive Cyberattack—What It Means for You SCADA / Cyber, cyber... etc / DERP COMBO!!! An Open Letter to Security Vendors - John Masserini (2015) Vendor Rebuf - Andy Ellis (2017) 10 Rules for Cybersecurity Salespeople - Mark Weatherford (2018) Advice to cybersecurity companies selling to CISOs - Patricia Titus (2020) Mailbag Dearest Liquidmatrix, It was so good to hear Jamie lose his ever-lovin' mind last episode. Dave alluded to being cranky during the brieflies. Can you please un-mute him and let us all hear him lose his mind for this episode? THANKS! ~The Entire Internet Briefly -- NO ARGUING OR DISCUSSION ALLOWED Amazing how far software defined radio has come lately - go do some learnin' on your RTL-SDR things Hackers claim to have carried off an enormous data heist on AMD, selling info on employee and customer information, future products and specs Upcoming Appearances:  -- more gratuitous self-promotion Dave: - Summer camp. (also, we will be adding GUESTS in the near future) James: - I'm trapped between Google Workspace, Slack, Jira, Salesforce, and Github. I can't find my way out. Help Advertising -  pay the bills... MattJay's Vulnerable U - he's got more subscribers than we do. And he's got sponsors and shit. Brawndo, the Thirst Mutilator. It's what plants crave. Closing Thoughts Seacrest Says: Inserting an old recording of Matt from early episode. Creative Commons license: BY-NC-SA

Foundations of Amateur Radio If you've heard the phrase "shortwave listeners", you might have wondered what on earth that was all about. It relates to the length of a radio wave used to transmit information. The length of a radio wave is tied to its frequency. The longer the wave, the lower the frequency. When radio amateurs talk about bands, like for example the 40m band, we're talking about a range of frequencies where the wavelength is around 40m. From a frequency perspective, this is around 7 MHz. The 160m band, at about 1.8 MHz, or 1,800 kHz is considered the beginning of the short wave bands. This implies that there are longer waves as well. If you've ever seen or owned a mid 1980's transistor radio, you'll have seen the notation MW, which stands for Medium Wave, today it's called the AM band. Older radios might have the notation LW, or Long Wave. The medium wave band is a broadcast radio band that runs between about 500 and 1,700 kHz. The wave length is between 600 m and 170 m. When radio was still in its infancy, there was also a popular long wave band, with wavelengths between 800 m and 2,000 m, or 150 to 375 kHz. Today much of that has gone by the wayside. With the advent of digital radio, in Australia it's called DAB+, Digital Audio Broadcasting, the whole idea of "wave" has pretty much vanished. Some countries like Japan and the United States are in the process of discussing the phasing out of the AM broadcast band. Much of that appears to be driven by car manufacturers who claim that the AM band is no longer useful or used, but forget to tell anyone that they really want to stop having to put AM radios in their cars because it's difficult to isolate the electrical noise from their modern contraptions in order to make it possible to actually listen to that band. If you ask me, it's a good incentive to make electronics RF quiet, something which is increasingly important in our wirelessly connected world. This might lead you to believe that all activity on air is moving to higher and higher frequencies, but that's not the case. The properties that made long wave and medium wave radio possible in the early 1900's are still valid today. For example, there are WSPR or Weak Signal Propagation Reporter beacons on the 2200m band, or at 136 kHz. Whilst your RTL-SDR dongle might not quite get down that low, most of them start at 500 kHz, you don't need to spend big to start playing. My Yeasu FT-857d is capable of tuning to 100 kHz, plenty of space to start listening to the 2200m band, even if I cannot physically, or legally, transmit there. If you want to build your own receiver, you can check out the weaksignals.com website by Alberto I2PHD where you'll find a project to build a receiver capable of 8 kHz to 900 kHz using a $50 circuit board. If that's not enough, there's radio experimentation happening at even lower frequencies. Dedicated to listening to anything below 22 kHz, including natural RF, with a wavelength greater than 13 km, Renato IK1QFK runs the website vlf.it where you'll find receivers and antennas to build. Given that most sound cards operate up to around 192 kHz, you can start by connecting an antenna to the microphone port of your sound card and use it to receive VLF or Very Low Frequencies. On your Linux computer you can use "Quisk" to tune. There are VLF transmitters on air. For example, SAQ, the Grimeton Radio Station in Sweden opened on the 1st of December 1924. Capable of 200 kW, today it uses about 80 kW and transmits twice a year on 17.2 kHz. While we search for higher and higher frequencies, there is still plenty of fun to be had at the other end of the radio spectrum. Consider for example that VLF or Very Low Frequency radio waves, between 3 and 30 kHz can penetrate seawater. I'll leave you to explore. I'm Onno VK6FLAB

Foundations of Amateur Radio Over the years you've heard me utter the phrase: "Get on air and make some noise!". It's not an idle thought. The intent behind it is to start, to do something, anything, and find yourself a place within the hobby of amateur radio and the community surrounding it. Since starting my weekly contribution to this community, thirteen years ago, almost to the day, I promise, this wasn't planned, you'll see why in a moment, I've been working my way through the things that take my fancy, things that are of interest to me, and hopefully you. From time-to-time I don't know where the next words are going to come from. Today they came to me five minutes ago when a good friend, Colin, VK6ETE, asked me what inspires me, after I revealed to him that I didn't know what I was going to talk about. That's all it took to get me rolling. There are times when getting to that point takes weeks, I do research, figure out how something works, explore how it might have been tackled before, if at all, and only then I might start putting my thoughts together, often I'll have multiple stabs at it and if I'm lucky, sometimes, something emerges that I'm astonished by. Today is much simpler than all that, since the only research required is to remember the people I've interacted with. Last week I met an amateur, Jess M7WOM, who was in town. Until last week, we'd never met and interacted only online. We discovered that we have a great many things in common. A joy for curiosity, exploration, technology, computers and a shared belief that we can figure out how to make things work. That interaction, over the course of a day, continues to fuel my imagination and provides encouragement to try new things. The same is true for a friend, Eric VK6BJW, who asked what they should do with the hobby after having been away for a long time with family, children, commitments and work. Just asking a few simple questions got the juices going and provided inspiration to start playing again. Another amateur was bored and claimed to have run out of things to do. A few of us started asking questions about their exposure to the hobby. Had they tried a digital mode, had they built an antenna, had they tried to activate a park, or as I have said in the past, any of the other 1,000 hobbies that are embedded within the umbrella that we call amateur radio. Right now I'm in the midst of working through, actually truth be told, I'm starting, Okay, actually, I've yet to start, reading the online book published at PySDR.org. Prompted by a discussion with Jess last week, I started exploring a known gap in my knowledge. I likened it to having a lamp-post in front of my face, I can see to either side, but in-between is this post, obscuring an essential piece of knowledge, how one side is connected to the other. In my case, on one side, I can see the antenna, how it connects to an ADC, or an Analogue to Digital Converter. On the other, I can also see how you have a series of bytes coming into your program that you can compare against what you're looking for, but the two are not quite connected, obscured by that .. post. I know there's a Fourier Transform in there, but I don't yet grok how it's connected. Recently I discussed using an RDS, or Radio Data Systems decoder, called 'redsea', connected to 'rtl_fm', in turn connected to an RTL-SDR dongle, that is, you connect an antenna to a cheap Digital TV decoder, tune to an FM broadcast station and use some software to decode a digital signal. It turns out that the PySDR book serendipitously uses this signal path as an end-to-end tutorial, complete with all the code and example files to make this happen. I actually read the chapter, but it's assuming some knowledge that I don't yet have, so I'm going to start on page one .. again. So, what has this got to do with Inspiration, you ask. Well, everything and nothing. Inspiration doesn't occur in a vacuum. It needs input. You cannot see light without it hitting something, radio waves don't exist and cannot be detected until it hits an antenna, the same is true for inspiration. It needs to hit something. You need to react, it needs to connect. That is why I keep telling you to get on air and make some noise. I'm Onno VK6FLAB

Foundations of Amateur Radio Much is made in our hobby about working DX, that is sending and receiving distant radio signals. How distant is up for debate. Depending on where you are, DX might be outside the continent, outside the country, or in my case you could easily say, anything outside of my state, since the nearest border is about 1,240 km away from here. For giggles, the distance between Albany in the South West and Wyndham in the North East of the state is 2,400 km and that's via radio wave. By car it's 3,570 km. To be clear, we're still inside VK6. All that to say, DX is in the ear of the beholder. If that's not enough, there's a group of amateurs who are of the strident opinion that for DX to count it must be a two-way contact. That is, both stations need to hear each other and as such, those amateurs believe that a mode like WSPR, the Weak Signal Propagation Reporter can't possibly be considered DX, even if you can discover that your station was heard on the other side of the planet. I'm going to skip right over those who tell anyone who will listen that FT8 isn't real radio because it's just computers talking to each other. This to give you some context when I introduce the next idea, namely FM Broadcast DX. I'm acutely aware that this isn't amateur radio, there's no two-way communication, it's probably not DX and besides, it's computers. That out of the way, let me tell you about something I discovered. Many, but not all, FM broadcasters transmit multiple signals when you tune to their station. One of those is a signal called RDS, or Radio Data Systems. It's used to show you the name of the station, sometimes what song is playing, what style of station it is and other information like road traffic alerts and emergencies. You can decode this using an RDS decoder. Recently I was browsing YouTube. I came across a video on the Broken Signal channel that digs into the world of FM-scanning to log any RDS information for the purpose of finding DX stations. The video goes into great detail on how to set this up with Windows, by copying files into various places, updating XML files, configuring sample rates, connecting virtual audio cables, running several tools simultaneously and it goes on to demonstrate how this all hangs together. While I was impressed with the idea, the implementation didn't speak to me, since I wince at the notion of copying random files into an application installation directory and besides I'm a Linux user. So, I went hunting. Turns out that there is an RDS decoder for Linux, called "redsea", written by Oona OH2EIQ. It's on GitHub. Compiling it is pretty straightforward, follow the instructions and it should work as advertised. You'll also need to have "rtl-sdr" installed so you can run a tool called "rtl_fm". Again Oona's instructions should help you out. I will add that I'm assuming that you have a so-called RTL-SDR dongle, it's a cheap USB device that can be coerced into pretending to be a software defined receiver with about 2.2 MHz of bandwidth. Based on the example shown, I immediately tuned to a local station and RDS information started filling my screen. To let you know how simple this is, you run the "rtl_fm" tool and send its output to "redsea" which decodes the information and displays it on the screen. That's it. No more moving parts, no XML files, no shenanigans with virtual audio cables and the like. Stage one complete, on to stage two, scanning. The "rtl_fm" tool has the capability to scan a range of frequencies. I tried this, but didn't really get anywhere, since for the scanner to work you need to set the squelch in order to switch between frequencies, but if you're aiming for a weak signal, it will never be heard if your local FM broadcasters are belting away 24 hours a day. So, instead I'm scanning each frequency between 87 MHz and 109 MHz, every 10 kHz, for 10 seconds, to see if there's any RDS data to be heard. I send that to a file and when I feel the urge, I can go check to see what I've heard. I haven't yet put this up on GitHub because I'm considering making it a contribution to the "redsea" project instead of a project of my own. Now, at this point you might wonder what all the fuss is about. Well, the same method could be used to decode your local amateur repeater idents, or the NCDXF beacons, or any other kind of interesting information. I saw one user link "rtl_fm" to "multimon-ng", a tool I've spoken about before. You should also check out Oona's website, windytan.com, there's a whole range of signal processing stories to be found, including dealing with flutter distortion on Steamboat Willie and a very cool spiral spectrogram. I'll leave you with one question. Why haven't you installed Linux yet? I'm Onno VK6FLAB

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Foundations of Amateur Radio Amateur radio is an activity enjoyed by many people around the world. How many exactly is cause for debate. The most recent official figure we have is from the IARU, the International Amateur Radio Union. In 2020 it counted over 3 million people, but an article written a year later puts that figure at 1.75 million. In Australia there's a common narrative that the total amateur population is in undeniable decline, some think that it's on a stark decline. Interested in hard data, for years I've been collecting information around the amateur population in Australia and I can report that across the nine years that I have data for the total variation is within two percent and it's not a straight line down either. There was a dip in 2020, potentially associated with training and callsign allocation being moved from the Wireless Institute of Australia to the Australian Maritime College, something which is going to change again shortly when amateur licensing in Australia will revert to the regulator, the Australian Communications and Media Authority. If you're familiar with amateur licensing in Australia, that's not the only change, but that's not what I'm looking at today, mainly because the available information associated with the upcoming changes are limited at best, seemingly buried in invective at worst. Back to the topic at hand. One of the often heard responses in relation to the decline of our hobby is recruitment of new amateurs. It's a topic that I've spent plenty of time over the past decade contemplating. How do you share the joy of amateur radio with a general public who is apathetic to the preconceived ideas associated with this hobby, you know, old white men sitting in the dark with Morse keys. For the record, I prefer a shack with light and I still don't know how to use a Morse key, other than to make my radio beep. The rest is genetic. In the quest for spreading the word there's a repeated emphasis on the young, often coalescing around the annual Jamboree on the Air, or JOTA, as organised between Scouting groups and radio amateurs. I have previously said that JOTA was how I first came across amateur radio, but at the time, aged 15 or so, I had no money for such endeavours and the experience didn't resonate with me until decades later. So, you could argue that this is what changed me into an amateur, but the reality is that I had to come across the hobby a few more times before I got interested enough to investigate, something which I have spoken about before, in short, Meg, then VK6LUX introduced me to the concept of controlling a 2.4 GHz drone using higher power than was permitted with standard Wi-Fi equipment. I was hooked and got my license less than a month later. I then discovered that I needed more permissions and set about studying, only to get distracted with everything I could already do. I'm still being distracted today. So, JOTA is a potential touch point, but I see little evidence that the initial spark goes anywhere in a hurry. I'm not dismissing it as a way to have amateur radio gain relevance outside our own community, but perhaps there are other ways to make this happen. In the early days of my journey I attended country fairs with my club and we'd set-up a radio or six to show and tell. There was talk of doing this in a shopping centre, at the local hardware store and even brief discussions about doing this at the local electronics store. As enjoyable as this was, none of it ever appeared to generate any permanent interest and I don't recall seeing new amateurs suddenly appear at the club after any outings. Last week Glynn VK6PAW and I, set-up at the local airport, YPPH, that's Perth International Airport if you're not familiar with the designation allocated by the United Nations arm, ICAO or the International Civil Aviation Organization. Perth has a public viewing area. It's situated at the south western end of runway 03/21. It's an elevated position with minimal shade, some seating and you're 320 m from the runway centreline. It's a place where plane spotters congregate and now a few radio amateurs. One thing we have in common is an interest in radio. We were told that the plane spotters often listen to one or two frequencies and if they're into video, they might record one radio channel to include on their YouTube videos. When Glynn and I visited we had a few radios with us. When I say few, in amateur terms we only had about five or so, but I suppose that comes with the territory. As it happens, admittedly not by accident, our radios could receive airband frequencies, so we could tune to Perth Tower, Perth Arrival, Perth Ground, Perth Departure and Melbourne Central, all at the same time. Next time we'll likely bring some HF gear so we can also listen to HF aviation frequencies as well. While I was hosting F-troop, the weekly net for new and returning amateurs, midnight UTC, every Saturday morning for an hour, Glynn was busy talking and sharing with the plane spotting community. There were conversations around what radios and antennas to use, how you could tune to more than one frequency at the same time, how you could use software defined radios, how to set-up radios so you could have different channels appear at the left or the right, in the middle, or somewhere in between, which will allow you to focus on a particular radio call as it happens. Also, I should mention a piece of software called rtl-airband which allows you to use an RTL-SDR dongle to do this at home, but I digress. There was a steady stream of people looking at planes and their age was surprising, aged 3 to 93 or so. Of course not all were into the radio, but plenty were. Afterwards it occurred to us that there might be other venues like this, attracting people who are interested in radio for their own purposes. I have no doubt that we'll be back to Perth Airport, but I suspect we'll also see if we can find some other spotters. Train, ship and other airports come to mind immediately. I can't wait to learn about other people's uses and interests in radio, even if radio isn't the main attraction in their hobby. Perhaps you can think of some that you'd like to share. Getting on air and making noise is one way to get outside, but publicly listening to frequencies that others are interested in is a perfect excuse to play with radios. I'm Onno VK6FLAB

Foundations of Amateur Radio Between decibels and milliwatts ... As you might recall, I've been working towards using a cheap $20 RTL-SDR dongle to measure the second and third harmonic of a handheld radio in an attempt to discover how realistic that is as a solution when compared to using professional equipment like a Hewlett Packard 8920A RF Communications Test Set. I spent quite some time discussing how to protect the receiver against the transmitter output and described a methodology to calculate just how much attenuation might be needed and what level of power handling. With that information in-hand, for reference, I used two 30 dB attenuators, one capable of handling 10 Watts and one capable of handling 2 Watts. In case you're wondering, it's not the dummy load with variable attenuation that I was discussing recently. I ended up using a simple command-line tool, rtl-power, something which I've discussed before. You can use it to measure power output between a set of frequencies. In my case I measured for 5 seconds each, at the base frequency on the 2m band, on the second and on the third harmonic and to be precise, I measured 100 kHz around the frequencies we're looking at. This generated a chunk of data, specifically I created just over a thousand power readings every second for 15 seconds. I then put those numbers into a spreadsheet, averaged these and then charted the result. The outcome was a chart with three lines, one for each test frequency range. As you'd expect, the line for the 2m frequency range showed a lovely peak at the centre frequency, similarly, there was a peak for the other two related frequencies. The measurement data showed that the power measurement for 146.5 MHz was nearly 7 dB, for 293 MHz it was -44 dB and for 439.5 MHz it was -31 dB. If you've been paying attention, you'll notice that I used dB, not dBm or dBW in those numbers, more on that shortly. From a measurement perspective we learnt that the second harmonic is 51 dB below the primary power output and the third harmonic was about 38 dB below the primary power output. First observation to make is that these numbers are less than shown on the HP Test Set where those numbers were 60 dB and 62 dB respectively. Second observation, potentially more significant, is that pesky dB thing I skipped over earlier. If you recall, when someone says dB, they're referring to a ratio of something. When they refer to dBm, they're referring to a ratio in relation to 1 milliwatt. This means that when I say that the power reading was 7 dB, I'm saying that it's a ratio in relation to something, but I haven't specified the relationship. As I said, that's on purpose. Let me explain. When you use an RTL-SDR dongle to read power levels, you're essentially reading numbers from a chip that is converting voltages to numbers. In this case the chip is an Analog to Digital Converter or an ADC. At no point has any one defined what the number 128 means. It could mean 1 Volt, or it could mean 1 mV, or 14.532 mV, or something completely different. In other words, we don't actually know the absolute value that we're measuring. We can only compare values. In this case we can say that when we're measuring on the 2m band we get a range of numbers that represent the voltage measured along those frequencies. When we then measure around the second harmonic, we're doing the same thing, possibly even using the same scale, so we know that if we get 128 back both times we might assume the voltage is the same in both cases, we just don't actually know how much the voltage is. We could say that there's no difference between the two, or 0 dB, but we cannot say how high or low the voltage is. This is another way of describing something I've discussed before, calibration. So, if I had a tool that could output a specific, known RF power level, and fed that into the receiver and measured, I could determine the relationship between my particular receiver and that particular power level. I could then measure at all three frequencies and determine if the numbers were actually the same for these three frequencies, which is what I've been assuming, but we don't actually know for sure right now. So, at this point we need a known RF signal generator. The list of tools is growing. I've already used a NanoVNA to calibrate my attenuators and I've used a HP RF Communications Test Set to compare notes with. At this point you might realise that we're not yet able to make any specific observations about using a dongle to make harmonic measurements, but you can make pretty pictures... There's a good chance that you're becoming frustrated with this process, but I'd like to point out that at the beginning of this journey I can tell you that I had no idea what the outcome might be and obviously, that's the nature of experimentation. If you have some ideas on how to explore further, feel free to get in touch. I'm Onno VK6FLAB

Hello and welcome to Episode 516 of Linux in the Ham Shack. In this deep dive episode, the hosts interview Aaron, the creator and maintainer of DragonOS about software-defined radios: …

Foundations of Amateur Radio Recently I had the opportunity to use a piece of professional equipment to measure the so-called unwanted or spurious emissions that a transceiver might produce. In describing this I finished off with the idea that you could use a $20 RTL-SDR dongle to do these measurements in your own shack. I did point out that you should use enough attenuation to prevent the white smoke from escaping from your dongle, but it left a question, how much attenuation is enough? An RTL-SDR dongle is a USB powered device originally designed to act as a Digital TV and FM radio receiver. It's normally fitted with an antenna plugged into a socket on the side. I'll refer to it more generically as a receiver because much of what we're about to explore is applicable for other devices too. Using your transceiver, or transmitter, as a signal source isn't the same as tuning to a broadcast station, unless you move it some distance away, as-in meters or even kilometres away, depending on how much power you're using at the time. Ideally we want to connect the transmitter output directly to the receiver input so, at least theoretically, the RF coming from the transmitter stays within the measuring set-up between the two devices. Assuming you have a way to physically connect your transmitter to your receiver we need to work out what power levels are supported by your receiver. For an RTL-SDR dongle, this is tricky to discover. I came across several documents that stated that the maximum power level was 10 dBm or 0.01 Watt, but that seemed a little high, since an S9 signal is -73 dBm, so I kept digging and discovered a thoughtful report published in August 2013 by Walter, HB9AJG. It's called "Some Measurements on DVB-T Dongles with E4000 and R820T Tuners". There's plenty to learn from that report, but for our purposes today, we're interested in essentially two things, the weakest and strongest signals that the receiver can accommodate. We're obviously interested in the maximum signal, because out of the box our transmitter is likely to be much too strong for the receiver. We're going to need to reduce the power by a known amount using one or more connected RF attenuators. At the other end of the scale, the minimum signal is important because if we add too much attenuation, we might end up below the minimum detectable signal level of the receiver. Over the entire frequency range of the receivers tested in the report the minimum varies by about 14 dB, so let's pick the highest minimum from the report to get started. That's -127 dBm. What that means is that any signal that's stronger than -127 dBm is probably going to be detectable by the receiver and for some receivers on some frequencies, you might be able to go as low as -141 dBm. At the other end of the scale the report shows that the receiver range is about 60 dB, which means that the strongest signal that we can use is -67 dBm before various types of distortion start occurring. For comparison, that's four times the strength of an S9 signal. So, if we have a 10 Watt transmitter, or 40 dBm, we need to bring that signal down to a maximum of -67 dBm. In other words we need at least 107 dB of attenuation and if we have a safety margin of two, we'll need 110 dB of attenuation, remember, double power means adding 3 dB. So, find 110 dB of attenuation. As it happens, if I connect most of my attenuators together, I could achieve that level of attenuation, but there's one further issue that we'll need to handle and that's power. As you might recall, an attenuator has several attributes, the most obvious one is how much attenuation it brings to the party. It's specified in dB. My collection of attenuators range from 1 dB to 30 dB. Another attribute is the connector it comes with, I have both N-type and SMA connectors in my collection, so I'll need some adaptors to connect them together. One less obvious and at the cheap end of the scale, often undocumented, aspect of an attenuator is its ability to handle power. Essentially we're turning an RF signal into heat, so an attenuator needs to be able to dissipate that heat to handle what your transmitter is throwing at it. I said that from a safety perspective I'd like to be able to handle 20 Watts of power. Fortunately we don't need all our attenuators to be able to handle 20 Watts, just the first one directly connected to the transmitter. If we were to use a 20 Watt, 30 dB attenuator, the signal through the attenuator is reduced to 0.02 Watts and the next attenuator in line only needs to be able to handle that power level and so-on. To get started, find about 110 dB of attenuation, make sure it can handle 20 Watts and you can start playing. Before you start keying up your transmitter, how might you handle a range of different transmitters and power levels and can you remove an attenuator when you test on a different frequency? On that last point, let me say "No", you cannot remove the attenuator when you're measuring a different frequency. I'm Onno VK6FLAB

Foundations of Amateur Radio Recently the Australian Space Weather Forecasting Centre issued an alert for a Coronal Mass Ejection or CME expected to impact Earth within 24 to 36 hours. This was presented within the context of seeing the resulting Aurora, but as a user of the HF radio spectrum, I'm subscribed to their email list, not for the pretty pictures, though I would be delighted to actually see them with my mark one eyeball, I'm on the list for the impact on propagation for my hobby. As a good citizen I shared the alert with my community both via email and social media and as a result I received some questions and comments. One question was, "What does this mean?", one comment was "it's not going to impact the United States." My response was to point out that HF propagation and the impact of the Sun is a very deep rabbit hole and encouraged further research by supplying several links, including a very detailed video by Rohde and Schwarz titled "Understanding HF Propagation", very, highly, recommended. Whilst watching that video I discovered that the Solar Flux Index is measured using a receiver tuned to 2800 MHz or 2.8 GHz. Being in the business of having receivers scattered around my shack, I asked myself if I had something that was able to receive on that frequency. My RTL-SDR dongle doesn't cut it without extra hardware, it tops out at 1.75 GHz. However, my PlutoSDR has a standard frequency range that goes up to 3.8 GHz out - of the box - and with some tweaks can make it to 6 GHz, so well and truly within range. Now, before I move on, I should mention that an RTL-SDR is a cheap, as-in $20, USB computer accessory that looks like a thumb-drive and is ostensibly built to receive digital television, or DVB-T signals. I've spoken about this previously. It can be used to receive radio frequencies outside the purpose it was built for. The PlutoSDR, or to give its official name the ADALM-PLUTO, on the other hand, something which I've also spoken about, is a single board Linux computer made by some smart people at Analog Devices, specifically for the purposes of learning and experimentation with receiving and transmitting RF. It comes with all manner of documentation and software and to be honest, I'm a little bit in love with mine. Back to measuring stuff. In this case I'm attempting to measure the power levels of radio frequencies at 2.8 GHz. I know of a simple tool called rtl_power that can measure RF power over time and started investigating if that tool had been hacked to be able to use the PlutoSDR, rather than the RTL-SDR dongle. It might have been, but I've not yet discovered it, however, that in turn led me to several other tools, most of which I'm still investigating. What it does tell me is that I'm not the first person to tread these paths, much has happened and been documented in the analogue sphere, some has been done using digital I/Q data and a transverter, a device that can multiply radio frequencies to make them appear in a different part of the radio spectrum, but I'm not yet sure if anyone has made a Solar Flux Index device out of a PlutoSDR. I recalled a wonderful little tool that I've also talked about before, there's a theme here, I'm sure, but the tool, "csdr", written by Andras HA7ILM, which allows you to do all manner of interesting things to a stream of raw data, specifically RF raw data. It has a function called logpower_cf which Andras describes as "useful for drawing power spectrum graphs", which is precisely what I'm looking for. Armed with that I'm now in the process of building a compiled version using Docker, so I can run csdr on my PlutoSDR and perhaps generate a power spectrum graph for 2.8 GHz. Of course that will now require that I learn how to extract raw data, known as I/Q data from the PlutoSDR command-line, process it through the logpower_cf function, output an image and hopefully show the result as a web-page. At the moment I'm still in the weeds with a Makefile, but that's not unusual. Needless to say that I'm working on it and the result will no doubt turn up on my github page when it's done. In the most innocent terms possible, how hard can it be? One takeaway that really needs to be expressed out loud, even if I've hinted at it. All the bits I've talked about here are things I've already been playing with. It wasn't until I came across a salient piece of information about the Solar Flux Index and how it was measured that all the puzzle pieces came together, the PlutoSDR, csdr, rtl-power, logpower_cf, the SFI and a web-server, that I could even imagine this happening. The point being that even if you have all of the puzzle pieces in your hands, it might still take one missing piece of information for your brain to go "Ah-ha, wow, yes, this makes sense, I can do this." So, keep collecting puzzle pieces, relevant to your own interests and one day you too will get to this point. I'm Onno VK6FLAB

Foundations of Amateur Radio A couple of days ago, after months of anticipation, an unassuming little box arrived on my doorstep. Inside the box was a nondescript electronic device with two SMA connectors and a USB socket. Other than the branding, there were no markings on the device and it came without any instructions. It did come with a couple of SMA adaptors, which came in handy. A little research later determined which of the two SMA adaptors connected to an antenna and which connected to a radio. The gadget itself is called an upconverter. It's an interesting little device that essentially mixes two frequencies together, creating two new ones, start with say 720 kHz and mix it with 120 MHz and you end up with 120.720 MHz and 119.28 MHz. In other words, if you mix two frequencies together, you end up with both the sum and the difference of those frequencies. If you have a radio that can listen to 120 MHz, but cannot listen to 720 kHz, then using an upconverter, you can, as it were, expand the frequency range of your radio to hear different signals. I purchased the upconverter with the intent of connecting it to my PlutoSDR, since the lowest frequency it can do is 70 MHz. Combine the two and I should be able to listen to all of the amateur HF frequencies at once. Given that my PlutoSDR is currently doing something else, I had a look at using the upconverter with my WSPR beacon monitor that uses an RTL-SDR dongle. Technically it's not required, since my particular dongle can be used to tune to HF frequencies, but as an experiment, it works well enough. So, I connected the antenna to the upconverter, the upconverter to the dongle and the dongle to a Raspberry Pi, a single board computer that runs Linux. Essentially the exact same setup I've been running for years, except that I inserted the upconverter between the dongle and the antenna. That and some power took care of the hardware. The software initially gave me some challenges. After discovering that the tool I'm using, rtlsdr_wsprd, has an option for an upconverter, I was up and running in minutes. So, at the moment, and for the next foreseeable little while, my WSPR monitor is using an upconverter to scan HF. Technically this should increase the sensitivity by a significant amount, since the dongle is better suited to tuning to higher frequencies than it is to lower ones, but only time will tell. I updated my monitoring scripts to take into account if the frequency I was monitoring was out of range, so it currently won't report on anything above 60 MHz, but then that's fine for what I'm working on. I've updated the script on github if you want to have a look. It's nothing fancy, it essentially checks to see if there's a file called upconverter and if so, it calls a slightly different monitoring script. Given that I have existing logging data associated with this monitor, I should be able to discover if there's any significant difference between what I've been monitoring to date and what's coming in now that an upconverter is in the listening chain. Theoretically, I should be able to hear weaker signals, but time will tell. One thing that was interesting whilst I was discovering how this all works and hangs together is that it wasn't immediately obvious how to set it all up in software. I tried several tools to make sense of the data. In the end the combination of gqrx, setting the local oscillator offset to a negative frequency, in my case 120 MHz, got me to the point where I could set the frequency to 720 kHz and hear my local broadcast station, whilst the software actually, secretly behind the scenes, added 120 MHz to that and tuned the radio to 120.720 MHz. Once I got my head around that, things started falling into place. The same is true for rtlsdr_wsprd, adding the upconverter flag with the value of 120MHz, got my monitoring station up and running. This is a pretty user friendly way of getting started with frequency mixers. You might recall my exploration into components apparently made from unobtainium. The intent is to use a variable frequency to achieve a similar thing, but that's a project still on the drawing board, for now, I have a fixed frequency, 120 MHz, which is plenty to get started. If you're curious why I'd want a stable variable frequency, consider for example, what might happen if you transmit from a HF frequency into an upconverter. Perhaps you could use your HF capable WSPR beacon to make a signal on 2m or 70cm. 120 MHz won't cut it, but perhaps you can work out what's needed to get from the 10m WSPR band to the 2m WSPR band, or the 70cm WSPR band. I'm Onno VK6FLAB

Foundations of Amateur Radio A little while ago I mentioned in passing that I was considering implementing a parrot repeater to help determine how your radio is performing. Discussion afterwards revealed that not everyone had the same picture in mind, so I thought I'd share with you some of what I'm considering and why. Most of the modern radio landscape revolves around hooking a computer up to some type of radio frequency capable device. Commonly it's the audio and control signals that travel between computer and radio, but there are plenty of examples where raw data makes the journey, like in the case of an RTL-SDR dongle. That journey is increasingly made using USB, the cable, not the sideband, and limits are based around the maximum speed that a Universal Serial Bus has. Essentially the amount of data that you can process is limited by how fast your computer can talk to the radio. For my parrot repeater, I'm imagining a device that can receive RF from any radio and process that signal to determine what the centre frequency is, the deviation, stability, the mode, what ever parameters I end up being able to determine, a whole other discussion on its own. In response, the idea is that the device generates a report and either presents that using text to speech, or as a web-page, or both. Using traditional methods, this would involve a radio, a computer, some software, connections between the radio and the computer, not to mention power for both the computer and the radio, an antenna and perhaps an amplifier. The picture I have in mind is not anything like that. I'm imagining a single device that takes power and does all I've described inside the one device. No external computer, no audio cables, no control cables, no hard drives, not anything, just a PlutoSDR and a power source connected to an antenna or two. You might think that's fanciful. As it happens, we already have some of that today. When I run dump1090 on my PlutoSDR, it presents itself to the world as a website that I can visit to see which aeroplanes are within range, where they are exactly on a map, what messages they're sending and where they're going. All of the processing is done inside the PlutoSDR. All I have to do is give it power and an internet connection. This is possible because the PlutoSDR is essentially a computer with RF. It runs Linux and you can write software for it. Unlike my Yaesu FT-857d, which also has a computer on board, rudimentary to be sure, but a computer none the less, it cannot be altered. I cannot load my own piece of software, launch a web browser and point it at my Yaesu, not without connecting an external computer that in turn needs to be connected to the radio. I might add, that this is is how many repeaters work and how devices that implement AllStar and Echolink manage to make the jump between the Internet and the world of RF. If your eyes are not lighting up right now, let me see if I can put it in different terms. The PlutoSDR has the ability to access signals between 70 MHz and 6 GHz. It can do so in chunks of 56 MHz. Said differently, if you were able to consider all of the amateur HF spectrum, from zero to 54 MHz, you could fit all of it inside one chunk of 56 MHz that the PlutoSDR is capable of. You couldn't send it anywhere, since you're limited to how fast a USB cable is, but you could technically process that inside the PlutoSDR itself. To get the PlutoSDR to see the amateur HF bands you could connect it to a transverter, in much the same way that today many 2m handheld radio owners use a transverter to get to 23cm, except in this case, we're going the other way. In order to actually use this massive amount of information, you're going to need to do some serious signal processing. Accessing 56 MHz of raw data is hard work, even if you don't have to get it across a serial connection. As it happens, the PlutoSDR also comes with an FPGA. As I've mentioned previously, it's like having a programmable circuit board, which can be programmed to do that signal processing for you. It has the capability to massage that massive chunk of data into something more reasonable. For example, you might be able to use it to extract each of the amateur bands individually and represent them as an image that you might show to the world as a waterfall on a web browser. Now to be clear, I'm not saying that any of this exists just yet, or fits within the existing hardware constraints. I'm only starting on this journey. I'll be learning much along the way. No doubt I'll be using existing examples, tweaking them to the point that I understand what they do and how they work. I've already been talking about some of this for years. As you might have discovered, this adventure is long with many different side quests and at the rate I'm going I'm confident that this represents the breadth and depth of what amateur radio means to me. So, if you're wondering why I'm excited, it's because the amateur radio world of opportunity is getting bigger, not smaller. I'm Onno VK6FLAB

From the Huntsville Hamfest, we sit down with Bob, W2CYK, and he shows us the new P10 Tablet from RFinder with RTL-SDR Receive and the traditional dual band DMR radio, just like the RFinder B1. Also on the B1 model, we get to see an updated version of the DMROIP software.

Foundations of Amateur Radio Recently a budding new amateur asked the question: "What radio should I buy?" It's a common question, one I asked a decade ago. Over the years I've made several attempts at answering this innocent introduction into our community and as I've said before, the answer is simple but unhelpful. "It depends." Rather than explaining the various things it depends on, I'm going to attempt a different approach and in no particular order ask you some things to consider and answer for yourself in your journey towards an answer that is tailored specifically to your situation. "What's your budget?" How much money you have set aside for this experiment is a great start. In addition to training and license costs, you'll need to consider things like shipping, import duties and insurance, power leads and a power supply, coax leads and connectors and last but not least, adaptors, antennas and accessories. "Should you buy second hand or pre-loved?" If you have electronics experience that you can use to fix a problem with your new to you toy this is absolutely an option. When you're looking around, check the provenance associated with the equipment and avoid something randomly offered online with sketchy photos and limited information. Equipment is expensive. Check for stolen gear and unscrupulous sellers. "What do you want to do?" This hobby is vast. You can experiment with activities, locations, modes and propagation to name a few. If you're looking at a specific project, consider the needs for the accompanying equipment like a computer if what you want to explore requires that. You can look for the annual Amateur Radio Survey by Dustin N8RMA to read what others are doing. "What frequencies do you want to play on?" If you have lots of outdoor space you'll have many options to build antennas from anything that radiates, but if you're subject to restrictions because of where you live, you'll need to take those into account. You can also operate portable, in a car or on a hill, so you have plenty of options to get away from needing a station at home. "Are there other amateurs around you?" If you're within line of sight of other amateurs or a local repeater, then you should consider if you can start there. If that doesn't work, consider using HF or explore space communications. There are online tools to discover repeaters and local amateurs. "Is there a club you can connect to?" Amateur radio clubs are scattered far and wide across the planet and it's likely that there's one not too far from you. That said, there are plenty of clubs that interact with their members remotely. Some even offer remote access to the club radio shack using the internet. "Have you looked for communities to connect with?" There is plenty of amateur activity across the spectrum of social media, dedicated sites, discussion groups, email lists and chat groups. You can listen to podcasts, watch videos, read eBooks and if all that fails, your local library will have books about the fundamental aspects of our hobby. "Have you considered what you can do before spending money?" Figuring out the answers to many of these questions requires that you are somewhat familiar with your own needs. You need a radio to become an amateur, but you need to be an amateur to choose a radio. To get started, you don't need a radio. If you already have a license you can use tools like Echolink with a computer or a mobile phone. If you don't yet have a license, you can listen to online services like WebSDR, KiwiSDR and plenty of others. You can start receiving using a cheap RTL-SDR dongle and some wire. "Which brand should you get?" Rob NC0B has been testing radios for longer than I've been an amateur. His Sherwood testing table contains test results for 151 devices. The top three, Icom, Kenwood and Yaesu count for more than half of those results. This means that you'll likely find more information, more support and more local familiarity with those three. I will point out that Rob's list has 27 different brands on it, so look around and read reviews both by people who test the gear and those who use it. And finally, "Why are you here?" It's a serious question. Different things draw different people into this community. Think about what you like about it and what you want to do more of. Take those things into consideration when you select your radio. As you explore the answers to these questions, you'll start building a picture of what amateur radio means to you and with that will come the answer to the question: "What radio should I buy as my first one?" If there are other questions you'd like to ask, don't hesitate to get in touch. My address is cq@vk6flab.com. I look forward to hearing from you. I'm Onno VK6FLAB

Foundations of Amateur Radio One of the questions you're faced with when you start your amateur journey is around connectors. You quickly discover that every piece of equipment with an RF socket has a different one fit for purpose for that particular device. That purpose includes the frequency range of the device, but also things like water ingress, number of mating cycles, power levels, size, cost and more. As an aside, the number of mating cycles, how often you connect and disconnect something is determined by several factors, including the type of connection, manufacturing precision and the thickness of the plating. That said, even a so-called low cycle count connector, like say an SMA connector lasting 500 cycles will work just fine for the next 40 years if you only connect it once a month. Back to variety. My PlutoSDR has SMA connectors on it as do my band pass filters, my handheld and one RTL-SDR dongle. The other dongle uses MCX. Both my antenna analyser and UHF antenna have an N-type connector which is the case for my Yaesu radio that also has an extra SO239 which is what my coax switches have. My HF antenna comes into the shack as an F-type and nothing I currently own has BNC, but stuff I've previously played with, does. When you go out on a field-day, you mix and match your gear with that of your friends, introducing more connectors and combinations. Invariably you acquire a collection of adaptors. At first this might be only a couple, quickly growing to a handful, but after a while you're likely to have dozens or more. My collection, a decade's worth, which currently includes more than 25 different combinations is over a hundred individual adaptors and growing. For most of the time these have been tossed into a little tool box with a transparent lid, but more and more as the collection and variety grew I started to realise that I was unable to quickly locate an adaptor that I was sure I had, since it had been used in a different situation previously. In addition to coming to the realisation that the reason I couldn't find a connector was because it was still in use, I began to notice that I had daisy chains of connectors. For example, my HF antenna has a PL259 connector that is adapted to an F-type connector with an SO239 barrel, a PL259 to BNC and a BNC to F-type adaptor. At the other end of the RG6 coax that runs from outside into the shack, the reverse happens, F-type to BNC and BNC to PL259. If you're counting along, that's five adaptors to get from PL259 to PL259 via F-type. At this point you might wonder why I'm using RG6 coax. The short answer is that I have several rolls of it, left over from my days as an installer for broadband satellite internet. RG6 is very low loss, robust and heavily shielded. Although it's 75 Ohm - a whole other discussion - in practice that's not an issue. What is a problem is that the only connectors available for it are F-type compression connectors. To get those to PL259 requires a step sideways via BNC. My point is that the number of adaptors is increasing by the day. I should acknowledge the existence of so-called universal connector kits. The idea being that you go from one connector to a universal joiner and from that to another connector. Generally these kits have around 30 connections, giving you plenty of options, but in reality more often than not, you only have half a dozen universal joiners, so your money is effectively buying you half a dozen conversions, great for a field day, not so great for a permanent installation. You could build your own collection and use something like SMA or BNC as your universal joiner, which is something I'm exploring. To keep track of my collection, recently I started a spreadsheet. It's essentially a list showing the number and types of connections. If you make a pivot table from that you'll end up with a grid showing totals of adaptors you have. You can use this grid to fill a set of fishing tackle boxes and all of a sudden you've got a system where everything has its own place. If you start this process you'll quickly notice that the table only needs to be half filled, since a BNC to SMA is the same as an SMA to BNC adaptor. This leaves you space to do some fancy footwork where the bottom right hand of the triangle can fit into the top left of the empty space, but I'll leave you to figure that out. My table also includes things like TNC and MCX adaptors, but I don't use those very often, so at the moment I'm putting them in their own box together with T-adaptors and other weird and wonderful things like FME and reverse SMA. For setting the order, I've gone for alphabetic, but if you have a better suggestion, I'm all ears. My email address as always is cq@vk6flab.com. What ideas have you come up with to organise the chaos that is your sprawling connector library? I'm Onno VK6FLAB

PODCAST: This Week in Amateur Radio Edition #1161 Release Date: May 29, 2021 Here is a summary of the news trending This Week in Amateur Radio. This week's edition is anchored by Chris Perrine, KB2FAF, Don Hulick, K2ATJ, Eric Zittel, KD2RJX, Will Rogers, K5WLR, George Bowen, W2XBS, and Jessica Bowen, KC2VWX. Produced and edited by George Bowen, W2XBS. Running Time: 1:31:16 Download Podcast here: https://bit.ly/TWIAR1161 Trending headlines in this weeks bulletin service: 1. As China Spacecraft Lands On Mars, Ham Notes Lander and Rover Separation 2. Amateur Radio Gearing Up For Another Active Atlantic Hurricane Season 3. CQ Announces 2021 Hall of Fame Inductees 4. June 2021 Eclipse Festival Seeks Ham Participants 5. East Bay SM Jim Siemons, W6LK, Stepping Down; Mike Patterson, N6JGA, Appointed 6. A CubeSat That produces Visible Light On The Ground To Be Launched In NASA Initiative 7. FCC Seeks Comment on Potential Impact of Global Semiconductor Shortage 8. Radio Amateur’s Vintage Home Movie Film Sheds Light on Hindenburg Disaster 9. Radio Amateurs of Canada Invites Participation in the RAC Canada Day Contest 10. Upcoming Listing of ARRL Learning Network Webinars 11. Amateur Radio News Shorts 12. Researcher and Past Arecibo Observatory Director Gordon Pettengill, W1OUN, SK 13. The San Francisco Amateur Radio Club Will Activate A Sailboat 14. First-Time Exam Applicants Must Obtain FCC Registration Number before Taking Exam 15. Spring ARRL Section Manager Election Results Announced 16. High Frequency Over The Horizon Radars Continue To Be Troublemakers, IARU Region One Monitoring Service Says 17. Indiana Amateurs Assist In Search For Missing Young Boy 18 .Bletchley Park Is Reopening 19. European Space Agency Is Having A Contest To Name Its New Spacecraft 20. The sun recently produced a massive solar flare and Coronal Mass Ejection 21. The German radio regulator has targeted certain solar panel electronics in interference issue 22. A major DXpedition is planned to Svalbard Island Plus these Special Features This Week: * Technology News and Commentary with Leo Laporte, W6TWT, will compare the differences between analog and digital audio at a basic level, and will tell us how we love our smart phones, and how they are slowly becoming an enemy. * Working Amateur Radio Satellites with Bruce Paige, KK5DO - AMSAT Satellite News * Tower Climbing and Antenna Safety w/Greg Stoddard KF9MP, will talk about what he perceives as a annual condition during the spring of each year called "Dead Band Syndrome." * Foundations of Amateur Radio with Onno Benschop VK6FLAB, will tell us how you can stream a dozen repeaters with an RTL-SDR dongle. * Weekly Propagation Forecast from the ARRL * Bill Continelli, W2XOY - The History of Amateur Radio. Bill returns with another edition of The Ancient Amateur Archives, this week, Bill Bill looks back to the days of Control Of Electromagnetic Radiation, better known as Conelrad. ----- Website: https://www.twiar.net Facebook: https://www.facebook.com/groups/twiari/ Twitter: https://www.twitter.com/twiar RSS News: https://twiar.net/?feed=rss2 iHeartRadio: https://bit.ly/iHeart-TWIAR Spotify: https://bit.ly/Spotify-TWIAR TuneIn: https://bit.ly/TuneIn-TWIAR Automated: https://twiar.net/TWIARHAM.mp3 (Static file, changed weekly) ----- Visit our website at www.twiar.net for program audio, and daily for the latest amateur radio and technology news. Air This Week in Amateur Radio on your repeater! Built in identification breaks every 10 minutes or less. This Week in Amateur Radio is heard on the air on nets and repeaters as a bulletin service all across North America, and all around the world on amateur radio repeater systems, weekends on WA0RCR on 1860 (160 Meters), and more. This Week in Amateur Radio is portable too! The bulletin/news service is available and built for air on local repeaters (check with your local clubs to see if their repeater is carrying the news service) and can be downloaded for air as a weekly podcast to your digital device from just about everywhere, including Acast, Deezer, iHeart, iTunes, Google Play, Spotify, TuneIn, Stitcher, iVoox, Blubrry, Castbox.fm, Castro, Feedburner, gPodder, Listen Notes, OverCast, Player.FM, Pandora, Podcast Gang, Podcast Republic, Podchaser, Podnova, and RSS feeds. This Week in Amateur Radio is also carried on a number of LPFM stations, so check the low power FM stations in your area. You can also stream the program to your favorite digital device by visiting our web site www.twiar.net. Or, just ask Siri, Alexa, or your Google Nest to play This Week in Amateur Radio! 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Foundations of Amateur Radio A while ago as part of my ongoing exploration into all things radio I came across a utility called rtlsdr-airband. It's a tool that uses a cheap software defined radio dongle to listen to a station frequency or channel and send it to a variety of different outputs. Originally written by Tony Wong in 2014, it's since been updated and is now maintained by Tomasz Lemiech. There are contributions by a dozen other developers. The original examples are based around listening to Air Traffic Control channels. I know of a local amateur who uses it to listen to and share the local emergency services communication channels, especially important during local bush fires. While sophisticated, it's a pretty simple tool to use, runs on a Raspberry Pi, or in my case, inside a Docker container. It's well documented, has instructions on how to compile it and how to configure it. Before I get into what I've done, as a test, let's have a look at the kinds of things that rtlsdr-airband can do. First of all, it's intended to be used for AM, but if you read the fine documentation, you'll learn that you can also make it support Narrowband FM. It can generate output in a variety of different ways, from a normal audio file, to an I/Q file - more about that at another time, and it can also send audio as a stream to a service like icecast, broadcastify or even to your local pulse audio server. If that last one doesn't mean much to you, it's a local network audio service, popular under Linux, but it runs on pretty much anything else thanks to the community efforts of many. So, on the face of it, you can listen to a channel, be it AM or Narrowband FM, and send that to some output, but I wouldn't spend anywhere as much time on this if that was all there was to it. The software can also dynamically change channels, support multiple dongles, or simultaneously listen to several channels at once and output each of those where ever you desire. Another interesting thing and ultimately the reason I thought to discuss it here is that rtlsdr-airband also supports the concept of a mixer. You can send multiple channels to a single mixer and output the result somewhere else. Using a mixer, in addition to setting cut off frequencies and other audio attributes, you can set the audio balance for each individual channel. This means that you can mix a channel exclusively to the left ear, or to the right ear, to both, or somewhere in between. Now, to add one extra little bit of information. In my location there's about a dozen or so amateur repeaters most of which can be heard at some time or another from my QTH. The frequency spread of those dozen repeaters is less than 2 MHz. A cheap RTL-SDR dongle can handle about 2.56 MHz. Perhaps you've not yet had the ah-ha moment, but what if you were to define an rtlsdr-airband receiver that listened to a dozen amateur radio repeaters - at the same time - and using the audio balance spread those repeaters between your left and right ear, you could stream that somewhere and listen to it. I'm sitting here with my headphones on, listening to the various repeaters do their idents, various discussions on different repeaters, a local beacon, incoming AllStar and other links, all spread out across my audio horizon, almost as if you can see where they are on the escarpment, though truth be told, I've just spaced them out evenly, but you get the idea. My original Raspberry Pi wasn't quite powerful enough to do this in the brute force way I've configured this, so as a proof of concept I'm running it on my main computer, but there's nothing to suggest that doing a little diligent tweaking won't make my Pi more than enough to make this happen. As for audio bandwidth, it's a single audio stream, so a dial-up connection to the internet should be sufficient to get the audio out to the world. I will point out that there may be legal implications with streaming your local amateur repeaters to the world, so don't do that without checking. For my efforts, this is an example of: "I wonder if ..." As it turns out, Yes you can. As it happens, my next challenge is to use this code on a PlutoSDR where the bandwidth is slightly larger, mind you, I'll have to do some fancy footwork to process the data without overwhelming the CPU, but that's another experiment in my future. What kind of crazy stuff have you tried that worked? I'm Onno VK6FLAB

In this edition: 01. Current edition of AMSAT Journal for members 02. AMSAT VP Engineering at JAMSAT 03. ARISS Press Conference on Columbus Radio System 04. Houston AMSAT Net #1400 - 28 years 05. BCCSAT-1 06. UNISAT-7 Schedule 07. UNISAT-7 Beacon 08. SpaceX bid on a NASA CubeSat launch 09. RTL-SDR article on receiving SMOG-P and ATL-1 10. ARISS Operation Mode 11. Join the 2021 Presidents Club 12. AMSAT Getting Started with Amateur Satellites digital 13. AMSAT Getting Started with Amateur Satellites print 14. AMSAT News Service 15. AMSAT Office Closed 16. AMSATs GOLF Program 17. AMSAT Hardware Store 18. AMSAT Gear on Zazzle 19. AMSAT Remove Before Flight Keychains 20. AMSAT Membership 21. Join AMSAT Presidents Club 22. AMSAT Donations 23. AMSAT on Twitter 24. and more.

Free SDR webinar! Our new webinar will introduce you to Software Defined Radios. "Why Every Scanner User Needs an SDR: The #1 Underrated Tool that should be in your setup" will be March 23, 2021. Register now at www.scannerschool.com/webinar --------------------------------------------------------------- Do you want to dive deep on Software Defined Radios? In this episode, Phil talks to listener Greg Weamer about his SDR setup. They get into the history of SDR development, what you can do with an SDR that you can’t do with a hardware-based scanner, and where they think the future of SDRs is heading. What You Need To Know Today, Greg does not have a hardware scanner at all, but only a SDR. His area has simulcast problems that the SDR solves. Greg currently uses about 8 RTL-SDR dongles, including 3 on a Raspberry Pi, some on another Raspberry Pi, an old laptop, and more. Greg also uses Trunk Recorder, which is one of the most difficult things he’s ever configured, but he loves that it monitors every voice channel at the same time. RDIO Scanner is a web interface that takes the feeds from the virtual recorders Greg has going and cues up calls on every voice channel so you don’t miss anything. Because it’s a web interface, he can bring it up on his phone or tablet from anywhere. Greg thinks the next major SDR development will eliminate the need for any fully hardware based radios entirely. An SDR can do things that not a single hardware-based scanner out there is capable of. Greg has used his SDR to tune into his utilities smart meters for his water and gas to track his usage. One of Greg’s favorite things about SDR is that you can see the signals and whether they’re strong or not, whether they’re digital or analog, etc. The ability to visualize the signal lets you find a lot more new stuff to listen to. The flexibility of an SDR and ability to do so many things at once with it means you get the equivalent of several premium subscriptions to other services. All session notes with links to the items we talked about an be found on our website at www.scannerschool.com/session168 --------------------------------------------------------------- Would you like 1 on 1 help? If you need help with your scanner and are looking for some one on one tutoring, I'd love to help you out.  Visit www.scannerschool.com/consulting to book your one hour appointment today! Help support Scanner School You can help support Scanner School by visiting our support page at www.scannerschool.com/support

Foundations of Amateur Radio One of the things about amateur radio that I find intensely fascinating and to be honest sometimes just as frustrating, is that you don't know what the outcome of an experiment might be at any one time. Not because you cannot control the experiment, or because you don't know what you're doing, but because the number of variables involved in most meaningful amateur radio experiments is pretty much infinite. I've spoken about this before, the idea that if you were to make a simple dipole antenna and fold the ends on each other, you'd have infinite variation in antennas with just a so-called simple antenna, since you can vary the shape of it in an unending variety of ways. The other day I was doing an experiment. An amateur radio one to be sure, but I was doing this within the realm of computing. I have been playing with digital modes for some time now and along the way shared some of what I've learnt. It occurred to me that I've been assuming that if you had the chance to follow along, you'd have access to the required hardware, simple enough, a $20 RTL-SDR dongle, but none-the-less, extra hardware. What might happen if you rule out that dongle and instead used a web-based receiver like WebSDR, or KiwiSDR, or any number of other such sites where you can pretty much tune to any band and frequency and see what's going on at a particular antenna location. For one it might allow you to decode something like APRS remotely, or decode an FT8 signal, perhaps even your own FT8 signal. Unfortunately most, if not all, of those sites include only the bare bones decoders for things like CW, AM, SSB and FM. After that you're pretty much on your own. You could do some funky stuff with a web-browser, linking it via some mechanism to the tool you use to actually decode the sound and there's some examples of that around, none that I really warmed to, since it requires that I open a web browser, do the mouse-clicky thing and then set-up some audio processing stuff. What if I wanted to figure out where the ISS was right now and wanted to listen to a receiver that was within the reception range of the ISS as it passed overhead, and automatically updated the receiver in real time as the ISS was orbiting the earth? For that to happen you'd need something like a command-line tool that could connect to something like a KiwiSDR, tune to the right frequency and extract the raw data that you could then decode with something appropriate. Turns out that I'm not the first person to think of this. There's even a project that outlines the idea of following a satellite, but it hasn't moved anywhere. There's also a project that is a command-line client for web-based KiwiSDR sites, but after spending some quality time with it and its 25 clones on github, I'm not yet at the point where this will work. Mainly because the original author made a design decision to record data to a file with a specific name and any clone I've found thus far only allows you to define what name to use. None so far actually appear to send their stream to something that can be processed in real time. Of course I could record a few minutes of data and process that, but then I'd have to deal with overlap, missing data, data that spans two files and a whole host of other issues, getting me further and further away of what I was trying to do, make a simple web-based audio stream digital mode decoder. As the Rolling Stones put it, "You Can't Always Get What You Want" And to me this sums up our hobby in a nutshell. When you call CQ, or go portable, or test an antenna, or attempt to build something new, there's going to be setbacks and unexpected hurdles. I think that it is important to remember that amateur radio isn't finished, it's not turn-key, no matter how much that appeals, you cannot find a one size fits all solution for anything, not now, not yesterday and not tomorrow. This hobby is always going to test boundaries, not only of physics, but your boundaries. It's after all one giant experiment. So, next time you don't get what you want, you might try something you find, and get what you need. Also, apologies to Keith Richards and Mick Jagger for butchering their words, a rockstar I am not. I'm Onno VK6FLAB

Free SDR webinar! Our new webinar will introduce you to Software Defined Radios. "Why Every Scanner User Needs an SDR: The #1 Underrated Tool that should be in your setup" will be January 26, 2021. Register now at www.scannerschool.com/webinar --------------------------------------------------------------- In this episode, Phil talks to "Fuzz the Pi Guy".   Fuzz has a large YouTube channel and has a ton of SDR and Raspberry Pi Videos. Fuzz and I discuss how he uses his Software Defined Radios and how he keeps costs down by using a Raspberry Pi as as his computer for many of these projects. What you will take away from this week's podcast: SDR stands for Software Defined Radio, where you plug your hardware into power on one end and your computer on the other end so the computer software can interpret the signal. The Raspberry Pi is essentially a low-cost computer to help teach computer science in schools, and is now used for things like hosting Minecraft servers, learning Linux, and running SDR programs. Fuzz has a YouTube channel where he primarily demonstrates Raspberry Pi projects and tips, as well as a wide variety of small electronics content. He’s using a new setup that involves a Raspberry Pi 3 with an RTL-SDR dongle, connected to a 2m 70cm homemade antenna to receive his local Phase 2 frequencies, uploaded to Broadcastify using the new free software OP25. Using this setup, Fuzz essentially created a Phase 2 scanner for under $100. The FlightAware website gives a good introduction to using the Raspberry Pi with an SDR that can get you set up in under 15 minutes. The Raspberry Pi has the best support system out there for any Pi hardware, but Fuzz has been working with the Atomic Pi lately. This setup provides an inexpensive alternative to buying a pricey scanner if you don’t mind troubleshooting and problem solving to get going. All session notes with links to the items we talked about an be found on our website at www.scannerschool.com/session164 --------------------------------------------------------------- Would you like 1 on 1 help? If you need help with your scanner and are looking for some one on one tutoring, I'd love to help you out.  Visit www.scannerschool.com/consulting to book your one hour appointment today! Help support Scanner School You can help support Scanner School by visiting our support page at www.scannerschool.com/support

Foundations of Amateur Radio Over the past little while I've been experimenting with various tools that decode radio signals. For some of those tools the signals come from space. Equipment in space is moving all the time, which means that the thing you want to hear isn't always in range. For example. The International Space Station or ISS has a typical orbit of 90 minutes. Several times a day there's a pass. That means that it's somewhere within receiving range of my station. It might be very close to the horizon and only visible for a few seconds, or it might be directly overhead and visible for 10 minutes. If it's transmitting APRS on a particular frequency, it can be decoded using something like multimon-ng. If it's transmitting Slow Scan TV, qsstv can do the decoding. I've done this and I must say, it's exciting to see a picture come in line-by-line, highly recommended. The National Oceanic and Atmospheric Administration or NOAA, has a fleet of satellites in a polar orbit that lasts about 102 minutes and they're overhead at least every 12 hours. You can use something like noaa-apt to decode the images coming from the various weather satellites, or a python script and I'll talk about that at some point. There is a growing cloud of cube satellites with interesting telemetry. They're in all kinds of orbits and you can attempt to receive data from each one as it's in sight. Keeping track of what's where and when is a full time job for plenty of people. As a radio amateur I'm happy to defer to the experts who tell me where a piece of equipment is and when I'm likely to be able to receive a radio signal from the transmitter I'm interested in. Previously I've mentioned in passing a tool called gpredict that does this heavy lifting for me. It presents a map of the world and shows what's visible at my location and when the next acquisition of signal for a particular satellite might occur. It talks to the internet to download the latest orbital information. It also has the ability to control a rotator to point your antenna, not that I have one, and it can update the transmit and receive frequency of your radio to compensate for the Doppler effect that changes the observed frequency as a satellite passes overhead. All this works with a graphical user-interface, that is to say, you have a screen that you're looking at and can click on. Whilst running gpredict, you can simultaneously launch the appropriate decoding tool for the signal that you're trying to receive. If you have a powerful enough computer, you can run multiple decoding tools together. You'll have separate windows for controlling the radio and antenna, for decoding APRS, SSTV, NOAA and if you're wanting to do sunrise and sunset propagation testing using WSPR, you can also run WSJT-X or any other decoder you're interested in. There are some implications associated with doing this, apart from needing a big enough screen, needing considerable computing power and burning electricity for no good reason, the signal that comes in from your radio will be fed to all the decoders at the same time and all of them will attempt to decode the signal, even when you know that this serves no purpose. That's fine if you don't know what you're listening to, but most of the time you know exactly what it is, even if the software doesn't. Manually launching and quitting decoders is one option, but what if the next ISS pass is at 3am? Aside from the computing requirements, so far this works fine with a standard analogue radio like my Yaesu FT-857d. The only limitation is that you can only receive one station at a time. If you replace the analogue radio with an RTL-SDR dongle, you gain the ability to record and decode simultaneous stations within about 2.4 MHz of each other. Another option is to use an ADALM Pluto and as long as the stations are within 20 MHz of each other, you can record and decode their signals. If you're not familiar with a Pluto, it's essentially a computer, receiver and transmitter, all in a little box, the size of a pack of cards. This is where it gets interesting. The Pluto doesn't have a screen, or a keyboard for that matter, but it's a computer. It runs Linux and you can run decoders on it. I've done this with ADS-B signals using a tool called dump1090. You'll find it on my GitHub page. One of the sticking points in decoding signals from space was the ability to predict when a satellite pass occurs without requiring a computer screen. Thanks to a command-line tool called "predict", written by John, KD2BD and others I've now discovered a way to achieve that. My efforts are not quite at the point of show-and-tell, but I've got a Docker container that's building and running predict on its own and using a little bash script it's telling me when the ISS is overhead. You'll find that on GitHub as well. My next challenge is to do some automated decoding of actual space signals. I'm going to start with the ISS, predict and multimon-ng. I'll let you know how I go. What space signals are you interested in? I'm Onno VK6FLAB

Foundations of Amateur Radio Amateur radio is a living anachronism. We have this heady mix of ancient and bleeding edge, never more evident than in a digital mode called Automatic Packet Reporting System or APRS. It's an amateur mode that's used all over the place to exchange messages like GPS coordinates, radio balloon and vehicle tracking data, battery voltages, weather station telemetry, text, bulletins and increasingly other information as part of the expanding universe of the Internet Of Things. There are mechanisms for message priority, point-to-point messages, announcements and when internet connected computers are involved, solutions for mapping, email and other integrations. The International Space Station has an APRS repeater on-board. You'll also find disaster management like fire fighting, earthquake and propagation reporting uses for APRS. There's tools like an SMS gateway that allows you to send SMS via APRS if you're out of mobile range. There's software around that allows you to post to Twitter from APRS. You can even generate APRS packets using your mobile phone. In my radio travels I'd come across the aprs.fi website many times. It's a place that shows you various devices on the APRS network. You can see vehicles as they move around, radio repeater information, weather, even historic charts of messages, so you can see temperatures over time, or battery voltage, or solar power generation, or whatever the specific APRS device is sending. As part of my exploration into all things new and exciting I thought I'd start a new adventure with attempting to listen to the APRS repeater on the International Space Station. I'm interested in decoding APRS packets. Seeing what's inside them and what kinds of messages I can hear in my shack. Specifically for the experiment at hand I wanted to hear what the ISS had to say. After testing some recommended tools and after considerable time hunting I stumbled on multimon-ng. I should mention that it started life as multimon by Tom HB9JNX, which he wrote in 1996. In 2012 Elias Oenal wanted to use multimon to decode from his new RTL-SDR dongle and in the end he patched and brought the code into this century and multimon-ng was born. It's available on Linux, MacOS and Windows and it's under active development. It's a single command-line tool that takes an audio input and produces a text output and it's a great way to see what's happening under the hood which is precisely what I want when I'm attempting to learn something new. In this case, my computer was already configured with a radio. I can record what the radio receives from the computer microphone and I can play audio to the radio via the computer speaker. My magical tool, multimon-ng has the ability to record audio and decode it using a whole raft of in-built decoders. For my test I wanted to use the APRS decoder, cunningly disguised as an AFSK1200 de-modulator. I'll get to that in a moment. The actual process is as simple as tuning your radio in FM mode to the local APRS frequency and telling multimon-ng to listen. Every minute or so you'll see an APRS packet or six turn up on your screen. The process for the ISS is only slightly different in that the APRS frequency is affected by Doppler shift, so I used gpredict to change the frequency as required; multimon-ng continued to happily decode the audio signal. I said that I'd get back to AFSK1200. The 1200 represents the speed, 1200 Baud. The AFSK represents Audio Frequency Shift Keying and it's a way to encode digital information by changing the frequency of an audio signal. One way to think of that is having two different tones, one representing a binary zero, the other representing a binary one. Play them over a loud-speaker and you have AFSK. Do that at 1200 Baud and you have AFSK1200. When you do listen to AFSK and you know what a dial-up modem sounds like, it will come as no surprise that they use the same technique to encode digital information. Might have to dig up an old dial-up modem and hook it up to my radio one of these days. Speaking of ancient. The hero of our story, APRS, dates back to the early days of microcomputers. The era of the first two computers in my life, the Apple II and the Commodore VIC-20. Bob WB4APR implemented the first ancestor of APRS on an Apple II in 1982. Then in 1984 he used a VIC-20 to report the position and status of horses in a 160km radius using APRS. As for the International Space Station, the APRS repeater is currently switched off in favour of the cross-band voice repeater, so I'll have to wait a little longer to decode something from space. I'm Onno VK6FLAB

Foundations of Amateur Radio One of the many vexing issues associated with getting on-air and making noise is actually making that happen. So, let's look at a completely restricted environment. An apartment building, seven stories off the ground, no ability to make holes, an unsympathetic council, restrictive local home owners association, et cetera, et cetera. On the face of it your amateur radio hobby is doomed from the start. In reality, it's only just beginning. So, to hear HF right now, today, you can go online and listen to a plethora of web-based software defined radios. There's the canonical WebSDR in Twente and a whole host of others using the same or similar software. There's KiwiSDR, AirSpy, Global Tuners, and many more. This will give you countless radios to play with, coverage across the globe, the ability to compare signals from different receivers at the same time on the same frequency, the ability to decode digital modes, find propagation, learn about how contests are done, the sky's the limit. I'll add that you don't need an amateur license for many of these resources, so if you're considering becoming part of the community of radio amateurs, this is a great way to dip your toe in the water. Think of it as a short-wave listening experience on steroids. I hear you say, but that's not amateur radio. To that I say, actually, it is. It's everything except a physical antenna at your shack or the ability to transmit. Permit me a digression to the higher bands. If you want to listen to local repeaters on UHF and VHF, listen to DMR and Brandmeister, you'll find plenty of online resources as well. You can often use a hand-held radio to connect to a local repeater which can get you onto the global Echolink, IRLP and AllStar networks. Failing that, there's phone apps to make that connection instead. Of course if you want to expand your repertoire to transmission, beyond a hand-held, you can. There are online transmitters as well. Many clubs have their club station available for amateurs to use remotely using a tool like Remote Hams. You'll get access to a radio that's able to transmit and you'll be able to make contacts, even do digital modes and contests. You will require an amateur license and access to such a station. Some clubs will require that you pay towards the running of such a service and often you'll need to be a member. Then there's actually going to the club, you know, physically, going to the club shack and twiddling physical knobs, though for plenty of clubs that's now also a computer since they're adopting software defined radios just like the rest of the community is. Using a radio via a computer can be achieved directly in the shack, but there's no reason to stay on-site. You can often use these radios from the comfort of your own shack. If you do want to get physical with your own gear, receiving is pretty simple. A radio with a wire attached to it will get you listening to the local environment. I have for example a Raspberry Pi connected to an RTL-SDR dongle that's connected to a wire antenna in my shack. It's listening across the bands 24/7 and reporting on what it hears. If you want to use an actual transceiver and you don't have the ability to set-up an antenna, kit out your car and go mobile. Failing that, make a go-kit with batteries, which as an aside will stand you in good stead during an emergency. Take your go-kit camping, or climbing, or hiking. Plenty of opportunities to get on-air and make noise. I hear you asking, what about having an antenna farm? Well, you can set one up in a farmers paddock and connect to it remotely - you will need permission from the land-owner - there's plenty of amateurs who use their country abode as a remote station. If you want to make noise at your actual shack, the antenna might be a piece of wire hanging from the balcony after dark, or an antenna clamped to the railing. You can use a magnetic loop inside your house. Some enterprising amateurs have tuned up the gutters in their building, or made a flagpole vertical, or laid a coax antenna on the roof. Have a look for stealth antennas, there's a hundred years of amateurs facing the same problem. My own station is very minimalist. There's literally a vertical antenna clamped to the steel patio. Using that I'm working the world with 5 Watts, 14,000 km on 10m, no kidding. Getting on-air and making noise doesn't have to start and finish with a Yagi on a tower. There's plenty of other opportunities to be an active amateur. I'm Onno VK6FLAB

Foundations of Amateur Radio When one WSPR receiver just isn't enough The other day during a radio play date, highly recommended activity, getting together with friends, playing radio, seeing what you can learn, we were set-up in a park to do some testing. The idea was an extension on something that I've spoken about previously, using WSPR, Weak Signal Propagation Reporter, to test the capabilities of your station. If you're not familiar with WSPR, it's a tool that uses your radio to receive digital signals from WSPR beacons across the radio spectrum. Your station receives a signal, decodes it and then reports what it heard to a central database. The same software can also be used to turn your station into a beacon, but in our case all we wanted was to receive. If you leave the software running for a while you can hear stations across many bands all over the globe. You'll be able to learn what signal levels you can hear, in which direction and determine if there are any directions or bands that you can receive better than any other. We set up this tool in a park using a laptop, a wire antenna and a radio running off a battery. In and of itself this is not particularly remarkable, it's something that has been done on a regular basis all over the globe, and it's something that I've been doing on-and-off for a few years. What made this adventure different is that we were set-up portable about a kilometre up the road from the shack, whilst leaving the main WSPR receiver running with a permanent antenna. This gave us two parallel streams of data from two receivers under our control, using different antennas in slightly different conditions, within the same grid-square, for the purpose of directly comparing the data between the two. Over a couple of hours of data gathering we decoded 186 digital signals, pretty much evenly split between the two receivers. More importantly, the stations we heard were the same stations at the same time which gave us the ability to compare the two decoded signals to each other. One of the aspects of using WSPR is that it decodes the information sent by a beacon. That information contains the transmitter power, the grid locator and the callsign. After the signal is decoded, the software calculates what the signal to noise ratio was of the information and records that, additionally giving you a distance and direction for each beacon for that particular transmission. I created a chart that showed what the difference was between the two, plotted against the direction in which we heard the decode. This means that you can compare which antenna can hear what in which direction in direct comparison against the other. In telling this story another friend pointed out that the same technique could be used to compare a horizontal vs. a vertical antenna, even compare multiple bands at the same time. It looks like I might have to go and get myself a few more RTL-SDR dongles to do some more testing. If you don't have a spare device, there's also the option of comparing other WSPR stations that share a local grid square, so you can see what other people near you can hear and if you like, use it as an opportunity to investigate what antenna system they're using. WSPR is a very interesting tool and putting it to use for more than just listening to a band is something that I'd recommend you consider. I've already created a stand-alone raspberry pi project which you can download from GitHub if you're itching to get started. Thank you to Randall VK6WR for continuing to play and to Colin VK6FITN for expanding on an already excellent idea. If you would like to get in touch, please do, cq@vk6flab.com is my address. I'm Onno VK6FLAB

Foundations of Amateur Radio Antenna testing in the field. If you've been around amateur radio for any time at all, you'll know that we spend an awful lot of time talking about antennas. How they work, where to get them, how to build them, how strong they are, how cheap they are, how effective, how resonant, you name it, we have a discussion about it. It might not be immediately obvious why this is the case. An antenna is an antenna, right? Well ... no. Just like the infinite variety of cars on the road, the unending choice of mobile phones, ways to cook an egg and clothes to wear to avoid getting wet, antennas are designed and built for a specific purpose. I've talked at length about these variations, but in summary we can alter the dimensions to alter characteristics like frequency responsiveness, gain, weight, cost and a myriad of other parameters. If we take a step back and look at two antennas, let's say a vertical and a horizontal dipole, we immediately see that the antennas are physically different, even if they're intended for exactly the same frequency range. Leaving cost and construction aside, how do you compare these two antennas in a meaningful way? In the past I've suggested that you use a coax switch, a device that allows you to switch between two connectors and feed one or the other into your radio. If you do this, you can select first one antenna, then the other and listen to their differences. If the difference is large enough, you'll be able to hear and some of the time it's absolutely obvious how they differ. You might find that a station on the other side of the planet is much stronger on one antenna than on the other, or that the noise level on one is much higher than the other. Based on the one measurement you might come to the conclusion that one antenna is "better" than the other. If you did come to this conclusion, I can almost guarantee that you're wrong. Why can I say this? Because one of the aspects of the better antenna is dependent on something that you cannot control, the ionosphere, and it is changing all the time. I have previously suggested that you listen to your antenna over the length of a day and notice how things change, but that is both time consuming and not very repeatable, nor does it give you anything but a fuzzy warm feeling, rather than an at least passing scientific comparison. A much more effective way is to set up your station, configure it to monitor WSPR, or Weak Signal Propagation Reporter transmissions using one antenna, for say a week, then doing it again with the other antenna. If you do this for long enough you can gather actual meaningful data to determine how your antenna performs during different conditions. You can use that knowledge to make more reliable choices when you're attempting to make contact with a rare station, or when it's 2 o'clock in the morning and you're trying to get another multiplier for the current contest. You don't even have to do anything different and spend little or no money on the testing and data gathering. You can do this with your normal radio and your computer running WSJT-X, or with a single board computer like a raspberry pi and an external DVB-T tuner, a so-called RTL-SDR dongle, or with an all-in-one ready-made piece of hardware that integrates all of this into a single circuit board. If you want to get really fancy, you can even use automatic antenna switching to change antennas multiple times an hour and see in real-time what is going on. You also don't have to wait until you have two antennas to compare. You can do this on a field day when you get together with friends who bring their own contraptions to the party. If there's any doubt in your mind, you can start with a piece of wire sticking out the back of a dongle. I know, I'm looking at one right now. I've been receiving stations across the planet. One thing I can guarantee is that the more you do this, the better you'll get a feel for how the bands change over time and how to go about selecting the right antenna for the job at the time. I'm Onno VK6FLAB

Foundations of Amateur Radio The hobby of Amateur Radio is essentially one of experimentation. Within our community we endlessly build things, from amplifiers to Yagis and every letter of the alphabet in between. With every experiment we grow the amateur radio sphere of influence just a little bit. As our hobby is evolving into Software Defined Radio, or SDR, the homebrew aspect of our community is also changing bit by bit and as a result, homebrew today is just as likely to be based on software as it is in hardware. Unlike the physical world where you need to source and buy components, design a circuit, build it, test it and then put it in a box, in the software realm you can get started with the computer that is more than likely within reach right now. Recently I took delivery of a new SDR, an ADALM Pluto. It's essentially a Linux computer, FPGA and transmit capable SDR in a small box. I bought it specifically for the purpose of experimentation. One of the first things I did with this device was install an existing piece of software called dump1090. The tool listens to 1090 MHz and decodes Mode S transponders, used by aviation to report aircraft information in real-time. Originally written by Salvatore Sanfilippo in 2012 for the RTL-SDR dongle, it was patched by several people and in 2017 it was updated by Jiang Wei to support the Pluto SDR. My contribution to the project is minor. I've updated the on-board web-server to use Open Street Map and a few other cosmetic changes. For me it was a "Hello World" project, something that's the software equivalent of warming up your soldering iron and pre-tinning the wire you're about to use. The tools to do this is what I want to discuss. When you look at the software that underlies much of the SDR world, the digital modes, logging, contesting, even the software inside tools like the Nano-VNA, much of it is open source. That means that as a curious amateur you can have access to the underlying equivalent of the circuit diagram. As you can with a soldering iron, a scribe and wire, you can patch or update a circuit. In the software realm you can do the same once you have access to the source code. The tools you're going to get in touch with are text editors, compilers, libraries and configuration files. If that's not your thing, I appreciate that, but if it sparks your interest, you'll open the door into a brand new world of software development where you can determine how a mode works or what it supports or how it interacts with your radio or testing gear. When you jump in, likely feet first, you're going to make mistakes and lose hair and sleep and you'll be shaking your virtual or physical fist at the person who came before you, but then that's the world of experimentation, so likely you'll already have that down pat. You'll likely play with different tools that require different versions, often installed side-by-side, much to your chagrin when you learn that it just won't work. Not to mention that removal of the offending tool often leaves interfering cruft behind, not unlike unsightly and short-circuiting blobs of solder. I'm here to introduce you, albeit briefly, to a tool that will take much of that pain away. The free tool is called Docker. It has got little in the way of visibility in the amateur radio world, but in the software development world it's pretty much old hat. Essentially the idea is that you can install stuff into a so called disposable container so you can have your copy of dump1090 installed in one container and your copy of codec2 in another, a copy of rtl-sdr in a third container, all working independently from each other, without needing to complicate things with multiple computers or virtual machines. If a developer uses Debian, another uses Ubuntu and a third uses Red Hat, you can run these side-by-side without any issue. If they need an ancient version of something, that too is handled without a problem. Make a mistake, destroy the container and start again, fresh. Docker is a tool that allows you to build an environment on Linux, MacOS and Windows, as well as the Raspberry Pi, that acts and behaves in many ways like a virtual machine. In all the ways that you're likely to use it, at least initially, it's indistinguishable. What that means is that the operating system, the compiler and the libraries that you need for one tool won't affect those needed for another tool. The best part of this is that you can build on a massive library of pre-existing Docker containers and use files that describe how to build and compile tools like dump1090. If you look for my callsign vk6flab on github.com, you'll find my version of dump1090 and you'll find a Dockerfile that describes how I built it. The project contains all the bits you'll need to get started with your own version of dump1090, or some other project that tickles your fancy. Every time you build something, the amateur radio sphere of influence grows just that little bit. I'm Onno VK6FLAB

Foundations of Amateur Radio In my day to day activities as a radio amateur I come in contact with people across all parts of their amateur journey. Some who don't yet know that they're amateurs, through to those who've just passed their test and are waiting for their callsign. Then there are those who have been amateurs for a while, experimented a bit and have settled down into the comfort of being a member of an active community. Stretch that further and I also spend regular quality time with amateurs who have been licensed longer than I've been alive. Recently I received an email from a freshly minted amateur. Just like me, still pretty much wet behind the ears, keen as mustard, trying very hard to figure out what to do next and where to go. The basic gist of the email from this amateur was that they didn't know what kind of antenna they could erect at their home and failing that, couldn't decide on what radio to acquire to match the antenna that they hadn't decided on, not to mention that the antenna needed to match the radio that didn't yet exist. If you've been around this community for a while you might recognise the chicken and the egg, which comes first, the antenna or the radio? The answer is obvious, hidden in plain sight, easy to deduce, simple to understand, and completely useless. Let me help you with the answer: It depends. If that didn't test your patience, even if you've been an amateur for longer than my parents have been alive, you'll know that this is an unanswerable question. So how do you break the egg and get started? Easy. Start somewhere. As it happens I have a recommendation. It's cheap, simple and it will get your feet wet sooner rather than later. My recommendation is neither, or both, depending on your perspective. I promise, I'll get to the point shortly. The reason I'm making it last and savouring the point, some might say, belabouring it, is because it's one that happens over and over again, day in, day out, year in, year out. My recommendation is that you spend $25 on an RTL-SDR dongle and hunt around your home for a piece of wire. That's it. If you're not familiar with an RTL-SDR dongle, it's essentially a USB thumb-drive sized device that plugs into the nearest computer and paired with the correct software it has access to many if not all of the frequencies that you as an amateur are allowed to play with. Given that it's a receiver, the antenna doesn't really matter all that much, at least not initially, so any piece of conductive wire will suit. Most dongles even come with an antenna of sorts, so you can get started straight away. Resources associated with this podcast are on the vk6flab.com website where I've also collected a few links under F-troop to get you on your way with an RTL-SDR dongle. The purist radio amateurs will likely arc up at this point and mention that this isn't real amateur radio, to which I can only say: Bah Humbug. Radio is about receiving as much as it is about transmitting. Any fool with two bits of wire can transmit, but it takes finesse to receive, so start there. There are other benefits from going this way. Other than ease of entry, that's another way of saying - cheap - you can easily spot where and when there is activity. You can use all the traditional modes like CW, SSB, AM and FM, but you can also play with all of the new modes like WSPR, FT8, JT65 and investigate some of the other modes like RTTY, PSK31, Olivia, SSTV and others. All this will help you have a better idea of the landscape you're stepping into without a major purchase. To really set a cat among the pigeons, I'm also looking into a Raspberry Pi based transmitter, rpitx by Evariste F5OEO. When that bears fruit I'll let you know. In the mean time, play, learn, listen, experiment. No need to spend hundreds or thousands of dollars while you're still unsure. Even if you already have a lovely amateur station, an RTL-SDR dongle is worth every cent and then some. I'm Onno VK6FLAB

Foundations of Amateur Radio Every person is the product of their environment. Unsurprisingly this is even true for radio amateurs. That's not too say that we can't break our mould, but it takes effort. I grew up around technology in the 1980's. As a result I'm familiar with 8-bit microprocessors like the Motorola 6502 which featured heavily at the time. I tend to think in terms of the presence or absence of a signal, rather than the intricacies of circuits and components. As a child of my time, I'm not particularly familiar with the punch card or paper tape, or core memory, or valves, 386 machine code or what's in an FPGA. As a direct result of my age, my knowledge and understanding of circuits is sparse at best. I understand basic components like resisters and capacitors in a DC setting, Ohms Law and the fun you can have with a battery, a few resistors, diodes and an LED light. As a radio amateur I've been introduced to how some things work differently in an AC circuit, like an antenna and a feed-line. Until very recently my knowledge about filters was based on what I'd read. I know that there is fun to be had with coax and stubs and other cute things, but how and why they work eluded me. Today I'm a step closer. Before I dig in and share some of what I've learnt, let's have a quick look at what a filter is and does. You'll have likely heard of high-pass and low-pass filters. You might have heard of band-pass and band-stop filters. If you think of a high-pass filter as a device that lets through high frequencies and a low-pass filter as a device that lets through low frequencies, we're already well on our way. If you put a high-pass filter together with a low-pass filter, you end up with a range of frequencies that doesn't pass, known as a band-stop filter. Similarly, if you tweak the frequencies that pass just so, you can combine a high-pass and a low-pass filter to make a band-pass filter. Let me illustrate. Imagine a 15m band-pass filter. It allows all frequencies in the 15m amateur band through, but blocks everything else. You could construct such a thing from a high-pass filter that allows 15m and above through combined with a low-pass filter that allows 15m and below through. Everything below 15m is stopped by the high-pass filter and everything above 15m is stopped by the low-pass filter. The gap between the overlap of the high-pass and low-pass filters is what creates a space where the 15m band gets through. If you move things around a little, the same can be constructed to make a 15m band-stop filter. Something that lets anything through, except a 15m amateur signal. To make such a gadget would require a low-pass filter that allows everything below 15m combined with a high-pass filter that lets everything above 15m through. So, if you can construct a high-pass filter and a low-pass filter, you can pretty much create any combination and allow or stop specific frequency ranges. If you're wondering why this might be useful, think about a contest. Two radios in the same shack. One transmitting on 15m and one on 40m. These two bands, one at 21 MHz and one at 7 MHz are third harmonics to each other. This means essentially that a radio on 40m affects one on 15m and vice-versa. If you had a set of filters that stopped 15m and passed 40m on one transceiver and a set of filters that stopped 40m and passed 15m on the other, both of you would be much happier. You don't need to do contesting to benefit from a filter. If you use an RTL-SDR dongle, it's affected by nearby strong signals, like say a local radio or television station. That's fine if that's what you're trying to hear, but not so much if you're trying to hear something else. Filters can help to make your life better. Now, to round this off at a suitable point, you can think of an inductor as device that lets low frequencies through but blocks high frequencies. Similarly, a capacitor is a device that blocks low frequencies but lets high frequencies through. So, it's fair to think of an inductor as a low-pass filter and a capacitor as a high-pass filter. The symbol for a capacitor is the letter C (Charlie) and for an inductor it's the letter L (Lima). You could make a circuit that either directly blocks from a certain frequency, or one that lets it through, but sends it to ground. This gives you two designs for a low pass filter one using an inductor or an RL circuit and one using a capacitor or an RC circuit. Similarly you can create a high-pass filter using either an inductor or a capacitor. That gives you four designs for two filters. Each of these can be combined to create band-pass and band-stop filters. The maths behind it isn't particularly daunting with basic high-school maths and if you want to see it happen before your eyes, check out the "Organic Chemistry Tutor" on YouTube. The play list you're looking for is cleverly disguised as "Electronic Circuits". As a direct result, I started hunting for breadboards, but it turns out that you can simulate these circuits online using any number of simulators. Of course there's going to be a gap between simulation and reality, but that's when you get out your soldering iron. Remember, if you smell chicken, you're holding it wrong. I'm Onno VK6FLAB

Welcome to another episode of scannertalkunlimited today we discuss the future of scanning and the major players in todays market and how RTL-SDR is slowly but surely becoming a contender, also I have been watching the stats and where I'm getting the most support from so shoutout to Oregon and Virginia for being the top supporters of the channel I appreciate you and I see you. I have done a few RTL-SDR projects trying to get the point of a portable efficient version of a portable RTL-SDR project but nothing like the ones I mention in the show which goes to show you people are making progress and in the next few years I see these going mainstream. If you haven't noticed I added Patreon support to the podcast show main page and if for whatever reason you can't see the link go to www.patreon.com/scannertalkunlimited and become a pledge today and support us and get some cool bonuses for yourself while your at it. --- This episode is sponsored by · Anchor: The easiest way to make a podcast. https://anchor.fm/app Support this podcast: https://anchor.fm/james-cole2/support

В этом выпуске выясняем, зачем следить за спутниками, какие сигналы можно от них принимать, что для этого нужно уметь и как таким образом можно помогать мировому научному сообществу. Ведущий: Антон Поздняков (https://twitter.com/kuingul), Гость: Андрей Родионов (https://twitter.com/dernasherbrezon) Темы [00:00:33] ⋅⋅⋅ Приветствие [00:01:13] ⋅⋅⋅ Что такое слежка за спутниками и зачем она нужна Проект r2cloud (https://github.com/dernasherbrezon/r2cloud) Проект SatNOGS (https://satnogs.org/) [00:03:56] ⋅⋅⋅ Оборудование необходимое для приема сигналов со спутников Примеры: антенна (https://amzn.to/2OSRSlB), кабели (https://amzn.to/34VqYPt), RTL-SDR (https://amzn.to/2YjiVJO), RaspberryPi (https://amzn.to/2sHur62) [00:09:23] ⋅⋅⋅ Какие данные можно принимать и что для этого нужно уметь [00:13:13] ⋅⋅⋅ Необходимое ПО для приема и декодирования сигналов из космоса [00:17:40] ⋅⋅⋅ Какие сложности есть в декодировании сигналов получаемых от спутников [00:26:15] ⋅⋅⋅ Какие данные передают спутники и в чем польза эти данные принимать [00:39:51] ⋅⋅⋅ Подводим итоги [00:46:51] ⋅⋅⋅ Прощание и переход в послешоу (https://www.patreon.com/posts/32112663/)

Foundations of Amateur Radio A while ago I set up a WSPR, or Weak Signal Propagation Reporter at home. Before I go into the details, WSPR is an amateur radio protocol that allows stations to transmit their callsign, location and power level and for receivers around the globe to decode those and upload the results to a central database. It's a great way to see what you can hear and what propagation is like. A couple of months ago the regulator changed the Australian License Conditions Determination, the rules of engagement around amateur radio and now all licensed amateurs in Australia can even set-up a transmitter although I haven't yet. Receiving is plenty of fun and anyone can do that. Initially I used a piece of Windows software to track the contacts but to me it was like ordering a courier with an 18-wheeler to pick up a postage stamp. I looked around an found a piece of software that runs nicely on a single board Raspberry Pi computer. The software is called rtlsdr_wsprd, it's a mouthful, but it works nicely on a Pi with an RTL SDR dongle. The dongle I have is capable of using all HF frequencies up to 1766 MHz, so I can technically hear the 23 cm band, though I haven't actually heard any stations there. I created a list of all the published WSPR frequencies and I listen to a frequency for fifteen minutes, pick another frequency at random and do it again, all day, every day. My log for this installation goes back about eight months and I get about a hundred contacts every month or so. You might think that's a lot of contacts, but really it's not. The antenna is indoors, it's under a metal roof and while it's on the second floor, it's far from ideal, but it works surprisingly well. What have I learned from this experience? I've heard 36 different stations, across 11 countries and 23 grid squares, the furthest was G0CCL, a club station in Cambridge in the United Kingdom which was transmitting on 20m with 5 Watts. I heard it 14750 km away. There are plenty of other things that I can extract from this. The most popular band is 20m, it accounts for nearly 70% of the contacts I heard. Surprisingly, I am also hearing contacts on 80m, as well as on every other amateur band that my receiver can hear. The 6m band is pretty popular too, nearly 13% of the stations I heard. For my receiver, between 4am and 6am in the morning was the best time to hear something, together they account for just under 20% of the contacts. Locally the worst time is 8am in the morning. From the data I've collected, April and May were the most active, accounting for nearly 70% of the contacts. I must point out that the log is not continuous, there's gaps when the logging station wasn't switched on and when I was switching antennas and locations, so using the statistics I've given you here for your own station are probably not going to work quite the same. The WSPR mode isn't perfect. It will happily decode rubbish and report on that, so I've manually filtered out the bogus information, like for example a grid square XI97LK, or callsign 3KE/21XWK, where neither the location or the prefix are real. I can tell you that I was surprised that my station can hear 80m on the little telescopic rabbit-ear antenna supplied with my dongle. That same antenna is also fine at hearing 6m, so I'm pretty happy with that. One thing that this little experiment reveals for me is that a cheap dongle is a perfectly fine way to start playing with a limited budget. It offers the opportunity to explore the RF spectrum using modern tools and techniques. Much of what I describe is absolutely possible with a traditional radio. Originally I had my station set-up like that. It consisted of my Yaesu FT-857d, a 12 V power supply, a CAT cable, an audio interface and a computer. In stark contrast, my current set-up consists of two things. A Raspberry Pi with an RTL SDR dongle plugged in. While this set-up cannot transmit, neither could I at the time. Since then there have been advances in both. There are all-band WSPR transmitters for a similar cost to a Pi and a dongle. Power it up, configure it and you're good to go. I'm eyeing off that as a future project, since it's perfect to use to see what bands are open for your station at any given moment. If you've never had a go, you should. I've documented how my monitor station works and you can find it on the projects page on my website at vk6flab.com. WSPR is a really nice way to get into many different aspects of our hobby and the barrier to entry is your imagination. I'm Onno VK6FLAB

Hello everyone and welcome to podcast # 3 in this episode we talk a little about scanner types and features and some rtl-sdr equipment and software. This episode was a little shorter today as I didnt have as much time to record and wasnt able to record in the jeep for this episode, I have been a little under the weather and have a lot of things going on in my life and job. Please leave comments and feedback for this podcast on my website at www.scannertalkunlimited.com, please remember this is all new and its a work in progress and will get better over time. Thanks in advance for listening and I hope you guys enjoy the content, it will become more focused as time goes on to specific topics and educational topics as I get some feedback --- This episode is sponsored by · Anchor: The easiest way to make a podcast. https://anchor.fm/app Support this podcast: https://anchor.fm/james-cole2/support

Hackaday Editors Mike Szczys and Elliot Williams curate the awesome hacks from the past week. On this episode, we marvel about the legacy RTL-SDR has had on the software-defined radio scene, turn a critical ear to 16-bit console audio hardware, watch generative algorithms make 3D prints beautiful, and discover why printer paper is so very, very bright white. Show Notes: https://hackaday.com/?p=370890

Foundations of Amateur Radio What would you do if you found that at random times your garage door opener didn't work, or the Wi-Fi network dropped out, or you couldn't switch off a light with an RF controller? That's the position I found myself in and the times at which this was happening were madly unpredictable. One moment everything would work fine and the next all things radio would just stop. As a radio amateur you're likely nodding your head and thinking, radio interference, there's some direction finding in your future. Sure enough, that's the case, but before that, I needed to know if the interference was random, if it had a particular pattern and how widespread it was, since it seemed to impact multiple different devices using different parts of the radio spectrum. Initially I focussed on getting a recording of it. I turned on my radio, tuned it to a 2m frequency and recorded the noise. Only one problem. There was no noise. All I could see was an extreme signal strength, but it wasn't showing up as noise. I enrolled the help of my RTL dongle and recorded some raw data, essentially capturing a 3 MHz slice of noise centred around 147 MHz. All that revealed was that there was noise. I already knew that. At that point I decided that a bigger hammer was needed. Something you can do if you have a $5 RTL-SDR dongle and some free software, in my case I used a tool called rtl_power and a visualisation tool called gnuplot. rtl_power is a nifty piece of software. It takes measurements and averages out the power level across the measurement range. To make it work, you specify a starting frequency, a stopping frequency, how big a step to use to average, how often you want to measure and for how long. For my little investigation I started with measuring between 0 and 1.7 GHz, at 1 MHz intervals, every 2 minutes for 10 days. That creates a big CSV file that you can process with gnuplot into a picture that tells a thousand lies. Seriously, it showed me that the interference was very wide, 0 to 300 MHz, it occurred every 20 or so hours, lasted up to six hour at a time. There were other things happening as well, similar patterns, but across an even larger frequency range, from 0 to 600 MHz, but in shorter duration and of lesser strength. Based on the times alone, I can immediately, almost certainly, eliminate any source under my control. Based on the timings I can also determine that the noise is likely not created by an automatic process, given that they vary in duration and the way they're clustered around specific times. The variation of the interference allows me to determine that there are at least three separate types of noise, each with specific characteristics and times, sometimes overlapping. It's too early to tell if this pattern will continue. One possible next step is to set up the same measurement tool and powering it from a battery. Once I've got that working, I expect to turn off the house power during an interference session and determine if the noise is coming from my house, or if it's an external source, which seems likely. Once I've determined if it's in house or not, I can start either eliminating gadgets by switching off specific power circuits, or I can start direction finding and locating a nearby source of pain. At that point I can decide what to do next. That said, at the moment it looks like several televisions around me are creating an RF noise storm of epic proportions. I've documented all of how I did this and you can find it and the scripts I created on the web at vk6flab.com. One thing that has happened since I started documenting my efforts is the idea that we could collectively as a community make measurements like this and document the state of our RF space and how it changes over time. I plan to update my code to incorporate this idea, perhaps log in 24 hour blocks and generate a chart over that time, perhaps make it into a video. One challenge ahead of us would be to come up with a universal way to calibrate our various dongles, so we all report the same signal level in the same way. One thought is to use the sun as a global calibration, but I'm not yet sure how that might be implemented. One thing's for sure. If you've ever wondered what use can a $5 RTL dongle possibly be, this is one thing that you just cannot do with a traditional radio. That's not to say there's a place for both in the world, just different tools for different problems. I'm Onno VK6FLAB

We share common mistakes that new SDR/Software Defined Radio users run into and how these problems can be avoided. We'll also go over a few interesting RTL-SDR.com blog articles.

In our first episode I go over the lunch of Es’hail sat 2 and it’s commissioning as QO-100 for amateur radio use, go over some of my favorite posts from the RTL-SDR blog and finally answer that age old question. What SDR should I get? You’ll find references and links to content mentioned in the Podcast below. Es’Hail sat – https://amsat-uk.org/satellites/geosynchronous/eshail-2/ The 3D Printed V Dipole Holder – https://www.rtl-sdr.com/3d-printed-v-dipole-holder-for-our-rtl-sdr-blog-multipurpose-dipole-kit/ Radwave’s RF Analyzer for Android – https://www.rtl-sdr.com/radwave-beta-android-rtl-sdr-rf-analyzer-app-with-spectrum-pause-and-rewind-features/ A tutorial on cloning 433 MHz devices: https://www.rtl-sdr.com/video-tutorial-using-universal-radio-hacker-an-rtl-sdr-and-a-microcontroller-to-clone-433-mhz-remotes/

Foundations of Amateur Radio Previously I've spoken about the joy of making something out of not much. On that theme I've covered WSPR, the Weak Signal Propagation Reporter, a mechanism to use a modest station to report signals received, which is something any suitably interested person can participate in, no license required. For a time I had my radio, a Yaesu FT-857D connected to a Windows XP notebook running WSJT-X, a piece of software that has the ability to set the frequency of your radio and then listen to what the radio is hearing, attempt to decode it and then report on what was heard. The beauty of this system is that you're using your own station to report signals heard, that is, your own antenna, your own coax, your own radio. Essentially you can use it to see what can be heard from around the world at your station. I had this running for a while, but the set-up was less than satisfactory, because I use the same radio and antenna to run weekly nets, the computer was running Windows XP and running out of disk space since WSJT-X has the option to save all the audio heard, which was clogging up my drive. It also meant that I was required to remember that I needed to reset the volume of the radio, set the squelch just so, disconnect and more importantly reconnect the antenna when there were storms about and a few other annoyances that became just a little too much for it to be fun. After doing this for a couple of months I just gave up and put it into the too-hard basket. The other day I started afresh. I started with a Raspberry Pi. It's a single board computer, about the size of a credit card, that comes in at about $30, is powered off a USB adaptor and runs Linux. Since I've been using Linux for around 20 years now, it seemed like a natural fit. I managed to obtain an RTL-SDR dongle which if you're not familiar, is essentially a USB device that you can use to listen to RF frequencies. Without going too deep, these gadgets started life as USB DVB-T and FM receivers, you know the USB dongles that you can plug into your computer to watch free-to-air TV or listen to FM radio. Back in March of 2010 Eric Fry got curious about figuring out if he could make a Linux version for one of the dongles work by reverse engineering the communication between the dongle and the supplied Windows software. In 2012 Antti Palosaari built on that and published his findings on the linux-media mailing list. Things exploded from there. So, an RTL-SDR dongle, connected to a Raspberry Pi, running Linux. At this point it would be great if I could report success and show and tell everything I've learnt, but then for that to happen I would need to actually have had success and I'm not quite there yet. I managed to decode one, count 'em, one, WSPR packet on 6m, once. Of course I couldn't help myself and started to improve things and since then I've not heard anything. I can tell you that there is plenty of documentation online about the subject, and I'll be adding my version of that once I've got mine up and running. There's a few things to work on, for example, listening on 6m is all fine and well, as long as there are 6m stations within hearing that are on and transmitting. Turns out that the station that I heard once last weekend has been switched off for a week. I've just changed bands, to see if that improves things, but only time will tell. I have also been using a mechanism to change bands automatically every 15 minutes, but without any spots I'm not sure if my set-up is working or not and I've just been unlucky not to hear anything. The challenges continue, but then I suppose that's why I'm here in the first place. I will add that a problem shared is a problem halved. I mentioned my challenge to a local amateur who sprang into action and set-up a WSPR beacon, just so I can test against it. I'll let you know how I go, or you can monitor for my spots on the WSPR website and celebrate when you see a spot with my callsign on it, because I will be, celebrating that is. As an aside, it continues to surprise me that this hobby has its fingers in so many different pies and my chosen profession of IT Geek is just another aspect of amateur radio. I'm Onno VK6FLAB

Foundations of Amateur Radio Often we forget the things we've done or achieved and every now and then it seems like a solid use of time to reflect a little on what went before and what that did. Recently I asked various amateurs what they were proud of having done or achieved in the past year, their little personal victory, their thrill to keep coming back to the hobby. For me it was the research and production behind "Is man-made noise really vertical?". It took several weeks to research and produce and received only a handful of responses on social media or via email, even though it was downloaded and read about 10,000 times or so. For me it gives me a thrill to have spent time digging into the Who, What, Why, When, Where and How of a topic that seems steeped in myth and often remains unexplained or unexplored. One amateur shared that they'd made their first HF contact from Perth to Romania, one had gotten their license this year after procrastinating for 30 years, another came back to the hobby after being away for a decade. There was an amateur who managed to set-up a rotatable Yagi on 6m. There were a couple of amateurs who have each been building a repeater network, another who built a 6m Yagi antenna and pre-amplifier, another who erected their tower after 5 years, another who managed to get an article published in the national amateur radio magazine, another who set-up their G5RV and connected it to an Air Spy to make WSPR spots after only a year and a half in the hobby. One amateur got their license upgrade and is looking forward to learning CW next year, another got their station fully set-up and returned to being an active radio amateur. There was an amateur who managed to get through a 20m SSB pile-up. A friend told me that their achievement of the year was to listen, both to others and themselves. There was an amateur who used 10 Watts to make a contact between Massachusetts and New Zealand, one who worked the SO-50 satellite with a Baofeng radio and a rubber duck antenna. One amateur managed to work AO-92 with the same type of gear, made two contacts and even has a recording from one of them. One amateur celebrated the arrival of their Bengali key, considering it Christmas before Christmas. One amateur who made their first contact between Texas and the Netherlands used a 20m self-built Moxon beam constructed from wire and fishing poles. There was an amateur who got their license and is impatient to get on air, it's been a week of waiting. One person upgraded to the top license class and actually started operating. One aspiring amateur was inspired by how easy it was to get licensed and is planning for their entrance as a licensed ham in the new year, mind you, that did't stop him from listening and decoding a NOAA satellite image using an RTL dongle. One amateur decided that he just couldn't wait for his license, studied three days and passed his test. He's now building his first radio, looking forward to making a contact. There's an amateur who joined the ranks and is now looking forward to going for an upgrade to his license next year. One ham has been licensed for 10 months and is already having a blast, erected his first real tower and now has a VHF antenna at 60ft, that's 20m up in the air. There's one amateur who has been learning about what a cheap RTL-SDR dongle can do with SDR# and he's saving up for an Icom 7300. He's finding it tough to balance between spending his money on high-end audio and saving for his Icom. Take it from me, the radio wins, every time! I've only scratched the surface of the activities undertaken in the past 12 months, but it's clear that being an amateur is a positive experience for many people, getting on air and making noise, learning, having fun, trying things and exploring this wonderful hobby is ingrained in much of the community. Before wrapping up, I'd also like to credit Will VK6UU for independently asking the same question and for the countless amateurs who responded, many of whom I wasn't able to squeeze in this time around. Perhaps I should do this more often. What's your proudest moment in the past 12 months? Let me know. I'm Onno VK6FLAB

It started as a normal episode - We invited Rod Hardman VA3ON and John Jacobs W7DBO (of the Field Radio Podcast) on to talk Holiday Shopping for Hams - one of our most favorite episodes to do each year.  During this session, we showed no restraint whatsoever because we were at the 4 hour mark when we stopped recording!  While we know you generally like long episodes, we thought we’d split this one into two parts. In part 2, we cover Ham Radio accessories and gifts for your Workbench. Now through the end of the year, save 25% on the 4-Port Coax Relay Switch - https://www.hamradioworkbench.com/store/p6/4-Port_Coax_Relay_Partial_Kit.html Save 10% off of a PowerFilm Solar 30 Watt Panel with Anderson Powerpole Adapter with code WORKBENCH 10 at checkout (through Dec 31, 2018) - 30 Watt Foldable Solar Panel with Anderson Powerpole Adapter Save $100 on the Digilent Analog Discovery 2 Package by using code “HamRadioWorkbench2018” in your cart prior to checkout - https://store.digilentinc.com/ham-radio-workbench-bundle/ Our Website - http://www.hamradioworkbench.com/ Follow us on Twitter - https://twitter.com/hamworkbench Contact us for feedback and ideas - http://hamradioworkbench.com/contact Connect with us on Facebook - https://www.facebook.com/groups/hamradioworkbench/ BrandMeister Talkgroup 31075 - https://hose.brandmeister.network/group/31075/ Case for 12V DC Power Strip from Rocket City 3d - https://rocketcity3d.ecwid.com/Ham-Radio-Workbench-12V-DC-Power-Strip-Case-p114464423 STLs for the 12V DC Power Strip  - https://pinshape.com/items/47791-3d-printed-ham-radio-workbench-dc-power-strip-case?fbclid=IwAR3a0sfN4r-QOCNCqr8bCKSKtBJBC4xuNA-Vm54-tppWr1wdRdI9TPBRfCM The Field Radio Podcast is not dead! - https://www.youtube.com/fieldradiopodcast SPRAT http://www.gqrp.com/sprat.htm RADCOM FROM THE RSGB https://rsgb.org/main/publications-archives/radcom/ National Contest Journal - http://ncjweb.com/ QRP Quarterly (QRP-ARCI Journal) - http://www.qrparci.org/ QEX: the forum for Communications Experimenters - http://www.arrl.org/qex RT Systems Programming Software - https://www.rtsystemsinc.com/ Rig Expert Antenna Analyzers - https://rigexpert.com/ Bird Watt Meters - https://www.birdrf.com/Products/Test%20and%20Measurement/Power-Meters/Wattmeters-Line-Sections/RF-Wattmeters.aspx RTL-SDR v3 Dongle - https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2/ref=sr_1_4?ie=UTF8&qid=1542432310&sr=8-4&keywords=rtl-sdr Anker Powerline USB Cables (Micro USB, Lightning, USB-C) - https://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Dmobile&field-keywords=anker+powerline Begali CW Paddles - https://www.i2rtf.com/keys---paddles.html MFJ-464 CW Keyer/Reader - https://www.mfjenterprises.com/Product.php?productid=MFJ-464 Bioenno Battery - https://www.bioennopower.com/ Powerfilm Solar Panel - https://www.powerfilmsolar.com/ RadioSport Headsets - http://www.arlancommunications.com/products/amateurRadio/ Goal Zero Crush Solar Lantern - https://www.goalzero.com/shop/lights/crush-light/ Heil HT Headset - https://heilsound.com/products/handie-talkie-headset-hth/ Fenix USB Lantern - https://www.amazon.com/rechargeable-neutral-dedicated-camping-EdisonBright/dp/B075QZRFSP/ref=sr_1_16?ie=UTF8&qid=1542424334&sr=8-16&keywords=fenix+lantern Fenix HL23 AA Headlamp https://www.amazon.com/Fenix-HL23-Headlamp-Champagne-EdisonBright/dp/B00UHZXAYG/ref=sr_1_3?ie=UTF8&qid=1542433548&sr=8-3&keywords=fenix+hl23 https://www.amazon.com/Goal-Zero-Light-Life-Light/dp/B016UQNG9E/ref=sr_1_3?ie=UTF8&qid=1542433912&sr=8-3&keywords=lightalife+mini Airforce Boonie Hat - https://uspatriottactical.com/r-b-airman-battle-uniform-boonie-hat-abu/ Improved MilSpec Rain Poncho - http://store.oldgrouch.biz/immipomainus.html Morseit by Picolabs CW App - https://pacolabs.com/iOS/MorseIt/ Free Amateur Radio Test Prep - https://HamStudy.org/ Coax Crimp Set (DX Engineering) - https://www.dxengineering.com/search/part-type/coaxial-cable-prep-tools Snap circuits - https://www.elenco.com/brand/snap-circuits/ Makeblock mBot Ranger Programmable Robot Kit - https://amzn.to/2TkgyDN Kuman K4-US for Arduino Project Complete Starter Kit - https://amzn.to/2TlO50d Chibitronics - LED Craft Kit - https://chibitronics.com/ QRP-Labs QRP Radio Kits - https://www.qrp-labs.com/ WinKeyer - https://www.hamcrafters2.com/ BITX QRP Transceiver Kits - http://www.hfsignals.com/ Hakko desoldering gun FR-301 - https://www.amazon.com/Hakko-FR-301-Desoldering-Tool/dp/B07BKSLLG9 Arduino sensor kit - ttps://www.ebay.com/itm/Ultimate-37-in-1-Sensor-Modules-Kit-for-Arduino-MCU-Education-User-Free-case/231757573899?hash=item35f5d3ef0b:rk:1:pf:0 Transistor kit - https://www.ebay.com/itm/840pcs-Transistor-TO-92-Assortment-24-value-NPN-PNP-DIY-kit-2N2222-S9018-BC32/332682436699?epid=12020296536&hash=item4d756b205b:rk:1:pf:0 Resistor kit - https://www.ebay.com/itm/130-values-2600pcs-1ohm-10M-ohm-W-Metal-Film-Resistor-Resistors-Assortment-Kit/221903164710?hash=item33aa759526:rk:1:pf:0 “The Radio Amateurs Workshop” - Joel Hallas W1ZR - http://www.arrl.org/shop/The-Radio-Amateurs-Workshop Ratcheting Wire Terminal Crimper - https://amzn.to/2OKEI6N MC4 Crimper https://amzn.to/2zhws9z Dupont Crimping Tool - https://www.amazon.com/IWISS-Professional-Compression-Ratcheting-Wire-electrode/dp/B00OMM4YUY/ref=sr_1_3?ie=UTF8&qid=1542437709&sr=8-3&keywords=dupont+crimping+tool

The Genesis of My Bill Of MaterialsParker RTL SDR functional setup? RTL-FM Seems to work fine for FM stuff AM works in direct sampling mode but I can’t seem to get that to work with RTL-FM Upconverter needed? Auto switching signals? RTL_FM also does not support stereo sound Might need a new option? R820T P7K5 Software Defined Radio? KiCad User improvements for MacroFab in the future KiCad Python API has awful documentation Particle Spectra Conference Workshops for IoT hardware and software MEP EP#122: Brandon Satrom and the LANoT Stephen Vox in a box tester layout is complete. Will order tonight May use this to also develop a preamp for a friends leslie rotary cabinet R.F.O. Parallax Propeller 2 Soon? Production samples work! Changes from First Prop 80Mhz -> 180Mhz 32 -> 64 I/O Hardware peripherals Built in Debugger Preliminary Specifications and Datasheet Ken Gracey and Chip Gracey on the Podcast? Luke Robertson from the Slack Channel How do you search for technical information? I am specifically thinking in regards to forums. I realize there is a niche forum for everything but I was wondering if there are a few standouts people prefer (presumably ones that aren't laced with kids looking for answers to their homework). Luke mentions Eevblog.com and diystompboxes.com Visit our Slack Channel and join the conversation in between episodes and please review us, wherever you listen (PodcastAddict, iTunes). It helps this show stay visible and helps new listeners find us.Tags: electronics podcast, KiCad, MacroFab, macrofab engineering podcast, MEP, Parallax Propeller 2, Particle Spectra, R820T P7K5, RTL_SDR, RTL-FM, Vox in a Box

Breaking Bad TapsParker Diagnosing power drops in the Wagon RTL SDR update? RTL-SDR for the Raspberry Pi Maybe a Live twitch session with some seasoned Python / SDR Peeps? Wrote about PCB Stackups for the MacroFab knowledge base Stephen Vox in a Box Power supply and Power amp have schematics Test Box Design for the power supply and power amp R.F.O. SQFMI Leaks new project #Watchy E-ink, ESP32 based, Accelerometer, 25 day battery life, Arduino support, and Open Source Productivity, Unfinished Projects, and Letting Go Steven Dufresne wrote this article for Hack A Day Doing Only The Interesting Parts Getting Lost on a Tangent Broken Taps Suck… Have you ever broken a tap? What is your method for removal? Raspberry pi development Pi-top? Visit our Slack Channel and join the conversation in between episodes and please review us, wherever you listen (PodcastAddict, iTunes). It helps this show stay visible and helps new listeners find us.Tags: #Watchy, Breaking Bad Taps, Breaking Taps, development, electronics podcast, Lost and Forgotten Projects, MacroFab, macrofab engineering podcast, MEP, PCB Stackups, Power Drops, Raspberry Pi, RTL SDR, SQFMI, Vox in a Box

The Amp Hour and Embedded join up to send a holiday letter to listeners. Chris G is ever improving Contextual Electronics. Chris W has a new band: 12AX7. Elecia still has a book: Making Embedded Systems. Amp Hour episodes mentioned in this one: 372: Where Chris and Dave talk about 2017 304: Alexa jokes 281: The first Amp Hour / Embedded show, with call ins 256: The first time Chris W was on the Amp Hour 187: Elecia joined the Amp Hour for the first time Embedded episodes mentioned: 223: Where Chris talks about his new synth habit 227: Talking about Udacity and learning 203: EE Charlie talks about good design We talked about teaching which led to: Short mention of Dreyfus model of skill acquisition of which Chris G’s friend Mel did a great explanatory comic Daniel Spalding’s How to Teach Adults (pdf) Dan Luu’s Learning To Program post Udacity’s Self Driving Car courses Computer vision with Python OpenCV Article on how the difficulty is the point of teaching literature The new art and engineering Function Podcast Hilarious World of Depression podcast Books we are reading! Build Your Own Transistor Radio by Ron Quan The Hobbyist’s Guide to RTL-SDR by Carl Laufer Spineless by Juli Berwald about Jellyfish Lost Art of Reading Nature’s Signs by Tristan Gooley Into the Drowning Deep by Mira Grant (terrifying mermaids) Catseye by Andre Norton Teach Beyond Your Reach by Robin Neidorf Mastery by Robert Greene Understanding By Design by Grant Wiggins and Jay McTighe Making Learning Whole by David Perkins Elecia got a JTrace Pro Cortex-M for herself for Christmas. Chris W got a Moog Werkstatt and an assortment of Teenage Engineering small synths. Chris G mostly got sweaters because Chicago is very cold. BMW now sends YouTube ads via snail mail

The BITX40 is a $60 Arduino controlled 7 watt QRP SSB 40 meter transceiver designed and built by Ashar Farhan VU2ESE.  They are available as a “kit” from http://www.hfsigs.com/ .  The assembly only involves soldering wires for things like speakers, power, and microphones and also finding a suitable case.  We originally spoke about the BITX40 back in Episode 26 (http://hamradio360.com/index.php/2017/06/20/ham-radio-360-workbench-26-the-bitx40-transceiver-an-introduction/) Mark “Smitty” Smith KR6ZY is back with us again to share with us the modifications and upgrades he’s made to the original BITX40 over the summer.  In this episode, we discuss adding upper sideband capabilities, adding an IF shift, and even multibanding the radio!  Smitty shares lots of great resources and ideas in this episode of the Workbench. Smitty KR6ZY can be found online on twitter @smittyhalibut (https://twitter.com/smittyhalibut) and on YouTube at https://www.youtube.com/user/SmittyHalibut Cale K4CDN is taking a much deserved break for the rest of the year!  - http://hamradio360.com/index.php/2017/09/19/ham-radio-360-lessons-from-irma-and-my-vacation/ Workbench Autodesk Eagle board layout tutorial with KF7IJZ, KJ6VU, W6KWF, and KR6ZY - https://www.youtube.com/watch?v=IYoorqf2llE OSHPark Board Manufacturer - https://oshpark.com/ ESP01 / ESP8266 http://www.instructables.com/id/Getting-Started-With-the-ESP8266-ESP-01/ https://www.sparkfun.com/products/13678 ESP Libraries Source https://github.com/esp8266/Arduino Arduino IDE - https://www.arduino.cc/en/Main/Software ESP8266 in Arduino - https://learn.sparkfun.com/tutorials/esp8266-thing-hookup-guide/installing-the-esp8266-arduino-addon Teensy - https://www.pjrc.com/teensy/ ARRL HF Data Rates - http://www.arrl.org/news/arrl-files-symbol-rate-petition-with-fcc Hardware random number generator - https://en.wikipedia.org/wiki/Hardware_random_number_generator RTL-SDR v3 with Direct Sampling - https://www.rtl-sdr.com/rtl-sdr-blog-v-3-dongles-user-guide/ QRP Labs Filter Kits https://www.qrp-labs.com LPFs: https://www.qrp-labs.com/lpfkit.html BPFs: https://www.qrp-labs.com/bpfkit.html HF BPF 10-band Set - http://shop.qrp-labs.com/BPFSET D-STAR QSO Party - https://www.icom.co.jp/world/dqp/ Silicon Dust HDHomeRun OTA TV to IP Box - https://www.silicondust.com/ Smitty’s BITX40 Intro Video - https://www.youtube.com/watch?v=3ESph5JCOpw BITX40 Mods Groups.io - https://groups.io/g/BITX20 BitX Hacks - http://bitxhacks.blogspot.com/ Raduino Software - https://groups.io/g/BITX20/wiki/Raduino-Topics Allard’s Software - https://groups.io/g/BITX20/wiki/Allard%27s-Raduino-Code Software upgrades https://github.com/amunters/bitx40/ Make it do CW http://bitxhacks.blogspot.com/2017/03/nd6t-bitx-cw-update.html http://bitxhacks.blogspot.com/2017/02/putting-bitx-raduino-on-cw.html USB and LSB (for digital) - https://groups.io/g/BITX20/wiki/USB-LSB-operation Front panel and case - https://www.banggood.com/Electronic-Plastic-Shell-Cartridge-Handle-Project-Case-Desk-Instrument-200x175x70mm-p-1035473.html?rmmds=myorder Optical/Rotary Encoder Tuning - https://groups.io/g/BITX20/topic/mouse_encoder/5553536?p=,,,20,0,0,0::Relevance,,mouse,20,2,0,5553536 Dr. Jack Purdum W8TEE VFO TFT - https://groups.io/g/BITX20/topic/5116056 AGC Board - http://kv4qb.blogspot.com/2016/11/bitx-40p-building-part-1.html   SteppIR Urban Beam - http://www.steppir.com/UrbanBeam  

This is a Digital Voice Modes Forum, recorded at the Dayton Hamvention 2017. We get to hear from Carl at RTL-SDR.com, then from Uli with Wireless Holdings, then finally Mel, K0PFX, about the FreeDV devices and applications for digital voice over HFhttp://livefromthehamshack.tv

This is a Digital Voice Modes Forum, recorded at the Dayton Hamvention 2017. We get to hear from Carl at RTL-SDR.com, then from Uli with Wireless Holdings, then finally Mel, K0PFX, about the FreeDV devices and applications for digital voice over HFhttp://livefromthehamshack.tv

In this episode of the Ham Radio 360 Podcast, I'm joined by Nick, KK6LHR to discuss ADS-B (Automatic Dependent Surveillance – Broadcast).  Known around here as "Tracking Airplanes with a SDR"...there's a lot more to it than that, and Nick helps me understand the ins and outs plus getting started in ADS-B. Automatic dependent surveillance – broadcast (ADS–B) is a surveillance technology in which an aircraft determines its position via satellite navigation and periodically broadcasts it, enabling it to be tracked. The information can be received by air traffic control ground stations as a replacement for secondary radar. It can also be received by other aircraft to provide situational awareness and allow self separation. *wikipedia Nick is more that just a nosy guy wanting to see what's flying overhead, he was determined to get the best signal down the line into his shack.  From Homebrewing LNA'a to Amazon he's compiled the gear and knowledge to help us make the most of our efforts! Thanks for coming on Nick, I really appreciate your time, helping this all make sense! Find all of your ADSB gear in this Kit! Show Notes & Links @ExplodingLemur QUCS:  Quite Universal Circuit Simulator - Official Site AIRSPY.US  SDR receivers and antennas SatelliteGuys.US Forum Workbench Antenna Analyzer Boards General info: FAA NextGen initiative ADS-B Wikipedia article Feeder sites: FlightAware FlightRadar24 PlaneFinder ADSB Exchange Windows software: PlanePlotter Virtual Radar Server Linux software: ADS-B Receiver project Dump1090 Dump978 Mlat-client Piaware Pfclient Fr24feed ADSBExchange scripts Stratux Hardware: Pair of RTL dongles and indoor antennas (low power consumption) RTL-SDR blog dongle NooElec dongle Low-noise amplifier Set of indoor antennas Dual-band antenna (no longer produced :( ) 1090MHz antenna 1090MHz antenna 978MHz antenna 1090MHz bandpass 1090MHz bandpass + bias-T Ham Radio 360 ADS-B KIT Post Show Mention on the RTL-SDR Blog   Thank you, again for listening and your support! Cale/K4CDN  

Chipotle and OneLogin suffer breaches, Windows XP Too Unstable To Spread WannaCry, Patches Available for Linux Sudo Vulnerability, Cisco, Netgear Readying Patches For Samba Vulnerability, oAuth nightmares, Attack and Defense, Jay Beale style, Decoding DECT with an RTL-SDR, and who are the Shadow Brokers? Full Show Notes: https://wiki.securityweekly.com/Episode516 Subscribe to YouTube Channel: https://www.youtube.com/channel/UCg--XBjJ50a9tUhTKXVPiqg Security Weekly Website: http://securityweekly.com Follow us on Twitter: @securityweekly

Chipotle and OneLogin suffer breaches, Windows XP Too Unstable To Spread WannaCry, Patches Available for Linux Sudo Vulnerability, Cisco, Netgear Readying Patches For Samba Vulnerability, oAuth nightmares, Attack and Defense, Jay Beale style, Decoding DECT with an RTL-SDR, and who are the Shadow Brokers? Full Show Notes: https://wiki.securityweekly.com/Episode516 Subscribe to YouTube Channel: https://www.youtube.com/channel/UCg--XBjJ50a9tUhTKXVPiqg Security Weekly Website: http://securityweekly.com Follow us on Twitter: @securityweekly

George and Jeremy bring all of the Microcontroller knowledge together to a practical application as they break down the building of the Sierra Radio Systems Bay-Net Repeater Groups Remote Site Monitoring System. Yaesu Announces two new Handhelds FT-25R - http://www.yaesu.com/indexVS.cfm?cmd=DisplayProducts&ProdCatID=111&encProdID=79E6683CC766565D2CB197C293AB6219&DivisionID=65&isArchived=0 FT-65R - http://www.yaesu.com/indexVS.cfm?cmd=DisplayProducts&ProdCatID=111&encProdID=82DE38083B3DFC155A6A472F7FEFA8C7&DivisionID=65&isArchived=0 RTL-SDR.com AM/FM Broadcast Band High Pass Filter – http://www.rtl-sdr.com/rtl-sdr-com-broadcast-block-high-pass-filter-now-sale/ Prebuilt Raspberry Pi Image for using an RTL-SDR as a receive iGate - http://www.rtl-sdr.com/a-pre-built-raspberry-pi-image-for-using-an-rtl-sdr-as-an-aprs-rx-igate/ KF7IJZ AGM / Bioenno LiFePO4 / NEC LiFePO4 Battery Comparison – https://youtu.be/psjQ-FT6KY0 Bay-Net articles - http://www.bay-net.org/articles.html Dupont Connectors - http://amzn.to/2lffzq0 Special Crimp Tool-Dupont Connector - http://amzn.to/2l3WBk0 Visit our Antenna Analyzer Forum for updates and hacks - http://hamradio360.com/community/main-forum/ Sierra Radio Systems – http://www.sierraradio.net/ Cactus Intertie – http://www.cactus-intertie.org/ Beagle Bone Black – https://beagleboard.org/black-wireless Wavenode – http://www.wavenode.com/  

Ham Radio 360: SDR (Software Defined Radio) My Buddies Jeremy (KF7IJZ) and Gerald (KF5JNU) are back together and this time they're taking us into the waters of SDR (Software Defined Radio) for the Amateur Radio Operator. SDR Radio is loved by some, yet misunderstood by most!  Like anything new, folks tend to steer clear thinking it's too complex or expensive.  In this show, Jeremy and Gerald break it down into digestible chunks that even Cale can understand!  From the $20 RTL-SDR Dongle as shown above, to the top of the line transceiver-the guys cover it ALL!   Geralds 'go to' SDR is the Airspy, and countless options are available for the hobbyist at differing levels of complexity and cost.  Listen in and determine where you'd like to get started in SDR! The ANAN  100B HF+6 Transceiver by Apache Labs is not just a listening device, it also is a Full-Power HF Transceiver! I really appreciate Jeremy and Gerald coming by and priming the SDR Pump, this has been a great launch for an Intensive Study on SDR! Stay Tuned Folks, we'll be following this rabbit hole all the way to the bottom!   Make sure to check out the links below!   73 Y'all (See you in Dayton!) K4CDN   GREAT Source for News and Information http://www.rtl-sdr.com/ Hardware - Receivers RTL-SDR:  http://www.rtl-sdr.com/ Nooelec:  http://www.nooelec.com/store/ SDR Play:  http://www.sdrplay.com/ Air Spy:  https://airspy.com/airspy-mini/ HackRF One:  https://greatscottgadgets.com/hackrf/ GREAT discussion of the differences between SDRPlay, Airspy, and HackRF: http://www.rtl-sdr.com/review-airspy-vs-sdrplay-rsp-vs-hackrf/ Hardware - HF Radios Elad:  http://www.woodboxradio.com/ Apache-Labs:  https://apache-labs.com/ Flex Radio:  https://www.flexradio.com/amateur-products/ Icom IC-7300: http://icomamerica.com/en/products/amateur/hf/7300/default.aspx Elecraft KX3:  http://www.elecraft.com/KX3/kx3.htm Software SDR#:  https://airspy.com/download/ SDR-Console:  http://sdr-radio.com/ GQRX: http://gqrx.dk/ Big List of Software:  http://www.rtl-sdr.com/big-list-rtl-sdr-supported-software/ Cool Things To Do Track Airplanes using ADS-B: http://www.instructables.com/id/Track-Airplanes-with-RTL-SDR-and-ADS-B/ Cheap Digital Scanner: https://www.jeffreykopcak.com/2014/12/12/p25-trunked-tracking-and-decoding-with-unitrunker-and-dsdplus/ http://www.rtl-sdr.com/rtl-sdr-radio-scanner-tutorial-decoding-digital-voice-p25-with-dsd/ https://www.youtube.com/watch?v=wShOLgW2tmI&feature=youtu.be APRS:  http://www.rtl-sdr.com/monitoring-aprs-rtl-sdr/ D-Star:  http://www.rtl-sdr.com/listening-d-star-digital-voice-dsd-1-7/ TAPR:  https://www.tapr.org/  

  Ham Radio-Listening to the Spectrum. A few months ago, Jeremy (KF7IJZ) and I were texting back and forth on show ideas.  He suggested we do a Radio Spectrum Show.  In Episode 38, that is exactly what we begin to do! Daunting huh? from the wiki Some newer hams may not be aware of what is out there to listen to.  Some may not know why they should or even how to listen to 'it'. There are receivers for everything.  Some are low-cost like the RTL-SDR dongle. Others are simple SWL Radios.  There are also specialized receivers for certain parts of the spectrum (ex: Police/Fire Scanners). While we try to cover it all, we also try to keep from getting bogged down too often (there is a lot to cover).  This is the Overview Program,  we have plans to bring you specific Band and Gear shows in the very near future! Thanks for listening! Beverage Antennas Numbers Station in Ukraine Addendum:  Freudian Slip..."Low-F'ers" not sure what happend there but my apologies to the Low-fers (loafers) at LWCA.org  and, like you I've been laughing since I heard it. *insert embarrassed emoji*  

Materials Available here: https://media.defcon.org/DEF%20CON%2023/DEF%20CON%2023%20presentations/DEFCON-23-Samy-Kamkar-README.txt Extras: https://media.defcon.org/DEF%20CON%2023/DEF%20CON%2023%20presentations/DEFCON-23-Samy-Kamkar-Extras.rar Drive It Like You Hacked It: New Attacks and Tools to Wirelessly Steal Cars Samy Kamkar Gary Numan said it best. Cars. They’re everywhere. You can hardly drive down a busy freeway without seeing one. But what about their security? In this talk I’ll reveal new research and real attacks in the area of wirelessly controlled gates, garages, and cars. Many cars are now controlled from mobile devices over GSM, while even more can be unlocked and ignitions started from wireless keyfobs over RF. All of these are subject to attack with low-cost tools (such as RTL-SDR, GNU Radio, HackRF, Arduino, and even a Mattel toy). We will investigate how these features work, and of course, how they can be exploited. I will be releasing new tools and vulnerabilities in this area, such as key-space reduction attacks on fixed-codes, advanced "code grabbers" using RF attacks on encrypted and rolling codes, and how to protect yourself against such issues. By the end of this talk you’ll understand not only how vehicles and the wirelessly-controlled physical access protecting them can be exploited, but also learn about various tools for car and RF research, as well as how to use and build your own inexpensive devices for such investigation. Ladies and gentlemen, start your engines. And other people’s engines. Samy Kamkar is a security researcher, best known for creating The MySpace Worm, one of the fastest spreading viruses of all time. He (attempts to) illustrate terrifying vulnerabilities with playfulness, and his exploits have been branded: “Controversial”, -The Wall Street Journal “Horrific”, -The New York Times “Now I want to fill my USB ports up with cement”, -Gizmodo He’s demonstrated usurping typical hardware for surreptitious means such as with KeySweeper, turning a standard USB wall charger into a covert, wireless keyboard sniffer, and SkyJack, a custom drone which takes over any other nearby drones allowing them to be controlled as a massive zombie swarm. He’s exposed issues around privacy, such as by developing the Evercookie which appeared in a top-secret NSA document revealed by Edward Snowden, exemplifying techniques used by governments and corporations for clandestine web tracking, and has discovered and released research around the illicit GPS and location tracking performed by Apple, Google and Microsoft mobile devices. He continues to produce new research and tools for the public as open source and open hardware. Twitter: @samykamkar