Foundations of Amateur Radio More WSPR adventures 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 TL;DR This is the transcript of the weekly 'Foundations of Amateur Radio' podcast - for other episodes, see http://vk6flab.com/
VK6FLAB / Onno, I've experemented with the WSPR with quite a bit of success in the past. Your adventures have inspired me to create a beacon. I intend to transmit on or around 7.0386, and I will hope to hear back from your call sign. Give me a few days to get it all set up. Hope to hear from you on the air waves!
Great timing on your post for me. For my ham radio project this weekend I successfully got a WSPR station working TX and RX on two raspberry pis I had sitting around. I'd judge the level of difficulty somewhere between moderate and difficult, depending upon your Linux skills. RX was definitely more challenging than TX for me due to all the software install and configuration needed. For what it's worth I've been a part time Linux enthusiast for about 15 years and a ham for about 2 years. For TX I used an old pi zero with a TAPR 20M WSPR-Pi controlled by WsprryPi. From my QTH in Dallas I got good reports on WSPRNET yesterday from stations on the left and right coasts and Canada on 0.1 watt output. I have it on my inverted V dipole in the backyard inside a ziplock bag to protect it from the elements. I'll look for something more permanent after I get it all figured out. The pi zero and a 2.5 amp power supply easily handle the load. For RX I have an old pi 3 model B with my RSP2pro running CubicSDR piped into WSJT-X. The base image for this pi is available from SDRplay, which made the setup easier. The antenna is a pair of wires on the high z port of the RSP2pro run around the baseboard inside. After just a couple hours in operation today I've successfully decoded transmissions from about 20 stations. I just applied for a WSPRNET account and plan to configure this rig to upload spots 24x7. This load on this pi is significant, and it runs pretty warm with ~50% CPU utilization (around 100% when CubicSDR is not minimized). Wifi and VNC make all this a joy to use after it's all set up. I just remote into the TX or RX pi from my laptop whenever I want to start/stop or check the status of something.
Onno, I hope that you are well and feeling/functioning much better ... Long time no chat The old QRO / QRP discussions. Interesting as always. Give it 5 years again - when solar conditions turn around - then the knives will be out for QRO again. Ahhh the WARS in AR... Predominantly ego and jealousy wars … people wanting to be big fish in little ponds … Don't we just love them???? A lot of these QRP modes are fantastic - but with a lack of regulation in many dominions low-power reporting modes is almost pointless in this low solar cycle. As examples for International readers using Australia with our regulator that ACMA that is toothless and unwilling to regulate. Amateurs receive basically zero service i.e. the ACMA again being powerless or unwilling to pursue fake C-Ticks and/or equipment that has had components removed since C-Tick certification was undertaken; likewise they argue that Amateurs have extremely sensitive, broad equipment that are very sensitive to noise and interference... Service cop outs ! It is not just in Australia where this occurs. [ This is why many Foundation callers just ignore the 10W power restrictions … as one can still make great local contacts; but as I restate during low solar-cycle environs DX contacts are so much more difficult to make.... Hence there are around 700 - 1000 Amateur Ops by accurate estimate out of the 13,000-odd Australian Amateurs that just plainly ignore the 400W limit … as without such power limits breaking "walls" of some ops that go feral when they see a DX station are near impossible ]. Just to stop knives coming back at me I do offer the disclaimer - QRP is not impossible under these conditions as long as one researches, understands, learns and advances. Yet it is made more difficult than it should be. Likewise I have always believed that QRO is QRP's greatest friend Summarising issues - Things will improve for QRP … but we also need to be equipped for the "bad times". Again nothing but best wishes for you and your ongoing health Onno 73 Steve I
Onno, Thanks for prompting me to try WSPR on Rasberry Pi 3 B+. Very new to Pi but had an RTL-SDR dongle on hand and loaded gqrx (pi experimental version) for SDR and WSJT-X for decoding. Using RTL-SDR in direct sample mode on 40, 30, and 20 m with good decoding success on WSPR. Had to cut back on sample rate in the gqrx to keep the Pi from overheating but that has not kept setup from working fairly well. 73, Keith - KE4TH
re: "A lot of these QRP modes are fantastic " The *advantage" of WSPR is, IF the transmitting station is honest, you know his or her transmitting power! It's there in the transmitted WSPR packet, and becomes part of the data record stored in the database. SO, if you wanna 'play' QRP after the fact, just subtract 20 dB from the reported SNR value if you *want* to see what your signal SNR would have been if you were running only 50 milliWatts instead of 5 Watts. Furthermore, you would likely not be seen with a power level of 50 milliWatts if your re-calculated SNR falls below -30 dB. At least with 5 Watts, you "showed up" and got an idea of what the path loss was, and if there is propagation to that receiving station.
Around 1300 in Australia. give me the real figures to how many Hams there really are in Australia. The reason is there are so many with 2 3 and 4 call signs owned by the same operator. These figures will drop by hugh numbers in the next 10 year because we are all getting old. And for sure and certain i wont be here. Pete VK6APZ.
