Starting in the wonderful hobby of Amateur or HAM Radio can be daunting and challenging but can be very rewarding. Every week I look at a different aspect of the hobby, how you might fit in and get the very best from the 1000 hobbies that Amateur Radio represents. Note that this podcast started in 2011 as "What use is an F-call?".
You Can't Always Get What You Want
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 y
Running out of things to do ...
Foundations of Amateur Radio
So, there's nothing on TV, the bands are dead, nobody is answering your CQ, you're bored and it's all too hard. You've run out of things to try, there's only so many different ways to use the radio and it's all too much.
I mean, you've only got CW, AM, SSB, FM, there's Upper and Lower Side-band, then there's RTTY, the all too popular FT8, then there's WSPR, but then you run out of things. I mean, right?
What about PSK31, SSTV, then there's AMTOR, Hellschreiber, Clover, Olivia, Thor, MFSK, Contestia, the long time favourites of Echolink and IRLP, not to forget Fusion, DMR, D-STAR, AllStar, BrandMeister or APRS.
So far I've mentioned about 20 modes, picked at random, some from the list of modes that the software Fldigi supports. Some of these don't even show up on the Signal Wiki which has a list of about 70 amateur modes.
With all the bands you have available, there's plenty of different things to play with. All. The. Time.
There's contests for many of them, so once you've got it working, you can see how well you go.
Over the past year I've been experimenting with a friend with various modes, some more successful than others. I'm mentioning this because it's not difficult to get started. Seriously, it's not.
The most important part of this whole experiment is getting your computer to talk to your radio. If you have FT8 already working you have all the hardware in place. To make the software work, you can't go past installing Fldigi. As a tool it works a lot like what you're familiar with. You'll see a band-scope, a list of frequencies and a list of decodes. It's one of many programs that can decode and generate a multitude of amateur digital modes.
If this is all completely new to you, don't be alarmed.
There are essentially two types of connections between your computer and your radio. The first one is audio, the second is control. For this to work well, both these need to be two-way, so you can both decode the audio that the radio receives and generate audio that the radio can transmit. The same is true for the control connection. You need to be able to set the transmit frequency and the mode and you need to be able to read the current state of the radio, if only to toggle the transmitter on-and-off. If you already have CAT control working, that's one half done.
I've spoken with plenty of amateurs who are reluctant to do any of this. If this is you, don't be afraid. It's like the first time you keyed up you radio. Remember the excitement? You can relive that experience, no matter how long you've been an amateur.
Depending on the age of your radio, you might find that there is only one physical connection between your computer and the radio, either using USB or even Ethernet. You'll find that your computer will still need to deal with the two types of information separately.
Notice that I've not talked about what kind of operating system you need to be running. I use and prefer Linux, but you can do this on any operating system, even using a mobile phone if that takes your fancy.
Getting on air and making noise using your microphone is one option, but doing this using computer control will open you to scores of new adventures.
I will add some words of caution here.
In general, especially using digital modes, less is more. If you drive the audio too high you'll splatter all over the place and nobody will hear you, well, actually, everyone will, but nobody will be able to talk to you because they won't be able to decode it. If the ALC on your radio is active, you're too loud. WSJT-X, the tool for modes like FT8 and WSPR, has a really easy way of ensuring that your levels are right, so if you've not done anything yet, start there.
Another issue is signal isolation. What I mean by that is you blowing up your computer because the RF travelled unexpectedly back up the serial or audio ca
What's in a prediction?
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.
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 ca
Changing of the guard ...
Foundations of Amateur Radio
When you begin your journey as a radio amateur you're introduced to the concept of a mode.
A mode is a catch-all phrase that describes a way of encoding information into radio signals.
Even if you're not familiar with amateur radio, you've come across modes, although you might not have known at the time.
When you tune to the AM band, you're picking a set of frequencies, but also a mode, the AM mode. When you tune to the FM band, you do a similar thing, set of frequencies, different mode, FM. The same is true when you turn on your satellite TV receiver, you're likely using a mode called DVB-S. For digital TV, the mode is likely DVB-T and for digital radio it's something like DAB or DAB+.
Even when you use your mobile phone it too is using a mode, be it CDMA, GSM, LTE and plenty of others.
Each of these modes is shared within the community so that equipment can exchange information. Initially many of these modes were built around voice communication, but increasingly, even the basic mobile phone modes, are built around data. Today, even if you're talking on your phone, the actual information being exchanged using radio is of a digital nature.
Most of these modes are pretty static. That's not to say that they don't evolve, but the speed at which that happens is pretty sedate.
In contrast, a mode like Wi-Fi has seen the explosion of different versions. During the first 20 years there were about 19 different versions of Wi-Fi. You'll recognise them as 802.11a, b, g, j, y, n, p, ad, ac and plenty more.
I mention Wi-Fi to illustrate just how frustrating changing a mode is for the end-user. You buy a gadget, but it's not compatible with the particular Wi-Fi mode that the rest of your gear is using.
It's pretty much the only end-user facing mode that changes so often as to make it hard to keep up. As bad as that might be, there is coordination happening with standards bodies involved making it possible to purchase the latest Wi-Fi equipment from a multitude of manufacturers.
In amateur radio there are amateur specific modes, like RTTY, PSK31, even CW is a mode. And just like with Wi-Fi, they evolve. There's RTTY-45, RTTY-50 and RTTY-75 Wide and Narrow, when you might have thought that there was only one RTTY. The FLDIGI software supports 18 different Olivia modes out of the box which haven't changed for a decade or so.
The speed of the evolution of Olivia is slow. The speed of the evolution of RTTY is slower still, CW is not moving at all. At the other end new amateur modes are being developed daily.
The JT modes for example are by comparison evolving at breakneck speed, to the point where they aren't even available in the latest versions of the software, for example FSK441, introduced in 2001 vanished at some point, superseded by a different mode, MSK144. It's hard to say exactly when this happened, I searched through 15 different releases and couldn't come up with anything more definitive than the first mention of MSK144 in v1.7.0, apparently released in 2015.
My point is that in amateur radio terms there are modes that are not changing at all and modes that are changing so fast that research is being published after the mode has been depreciated. Mike, WB2FKO published his research "Meteor scatter communication with very short pings" comparing the two modes FSK441 and MSK144 in September 2020, it makes for interesting reading.
There are parallels between the introduction of computing and the process of archiving. The early 1980's saw a proliferation of hardware, software, books and processes that exploded into the community. With that came a phenomenon that lasted at least a decade, if not longer, where archives of these items don't exist because nobody thought to keep them. Floppy discs thrown out, books shredded, magazines discarded, knowledge lost.
It didn't just happen in the 1980's
The Vagabond HAM
Foundations of Amateur Radio
This podcast began life under the name "What use is an F-call?" and was renamed to "Foundations of Amateur Radio" after 206 episodes. To mark what is effectively this, the 500th episode, I considered a retrospective, highlighting some of the things that have happened over the past decade of my life as a radio amateur. I considered marking it by giving individual credit to all those amateurs who have helped me along the way by contacting me, documenting things, asking questions, sharing their experiences or participating in events I attended. Whilst all these have merit, and I should take this opportunity to thank you personally for your contribution, great or small, to amateur radio, to my experience and that of the community. Thank you for making it possible for me to make 500 episodes, for welcoming me into the community, for being a fellow amateur. Thank you.
During the week I received an email from Sunil VU3ZAN who shared with me something evocative with the encouragement to bring it the attention and appreciation it deserves.
By way of introduction, on the 13th of June 2002, Ken, W6NKE became a silent key. Ken was an amateur, an active one by all accounts. I never met Ken, but his activity list is long and varied. Ken became interested in ham radio as a teenager in the 1930s. He was a long time advocate of CW and during WWII he taught Morse code to Navy operators. In 1975 he founded The Sherlock Holmes Wireless Society and was editor of its newsletter, now called "The Log of the Canonical Hams". He received his Investiture from The Baker Street Irregulars in 1981. Ken was an early member of the International Morse Preservation Society or FISTS, he held number 0818. He was the President of Chapter 2 of the Old Old Timers Club, the OOTC for many years. In addition to drawing cover art, Ken also wrote. Lots. 73 magazine features plenty of Ken's articles with titles like: "Inexpensive Vertical", "Don't Bug me Dad" and "The DX Hunter".
Ken was also a poet, which brings us to the way that I think is appropriate to mark the 500th episode of this podcast. I'm confident that you can relate to this contribution by Ken to amateur radio, published in Volume 1, Number 3 of 73 magazine in December 1960.
The Vagabond HAM, by Ken Johnson W6NKE (SK)
A vagabond's life is the life I live
Along with others, ready to give
A friendly laugh and a word of cheer
To each vagabond friend, both far and near.
I travel the air waves, day or night
To visit places I'll never sight
From the rail of a ship, or from a plane
Yet I'll visit them all again and again.
I never hear from a far off land
That my pulse doesn't quicken. With careful hand
I tune my receiver and VFO dial
To make a new friend and chat for awhile.
Africa, Asia, they're all quite near
In as easy reach as my radio gear
With the flip of a switch, the turn of a knob
I can work a ZL, a friend named Bob.
There's an LU4, a fellow that's grand
Who's described to me his native land
'Till I can hear the birds, and feel the breeze
As it blows from the slopes of the mighty Andes.
I learned of the surf, and a coral strand,
The smell of hybiscus where palm trees stand
'Neath a tropical moon, silver and bright
From an FO8 that I worked one night.
I've thrilled to the tales of night birds' screams
In the depths of the jungle where death-laden streams
Flow'neath verdant growth of browns and greens
From a DU6 in the Philippines.
The moors of Scotland, a little French Shrine,
German castles on the River Rhine
Of these things I've learned, over the air
Without ever leaving my ham shack chair.
There's a KL7 on top of the world
To whom the Northern Lights are a banner unfurled
That sweeps across the Arctic night
Makes the frozen sky a thing of delight.
Tales of silver and gold and precious stones
Ancient temples and molding bones
Where the natives, I'm told, are
The APRS of it all ...
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 w