After channelling your RTTY ...

Foundations of Amateur Radio

It's the morning after the day before. I've been calling CQ for 24 hours and for the first time in my life after a contest I still have my voice. That in and of itself is novel. I also don't have ringing ears, that's a blessing. I have learnt heaps and had fun doing it. I made contacts and I heard stations across the globe and I did it all from the comfort of my shack chair.

Before I dig in and expand, the contest I just completed ran for 24 hours. I didn't sit at my radio for all of it, nor was my radio on for all of it. I managed to have lunch, dinner, desert, breakfast and morning tea. I snuck in a few naps and I managed to help with bringing in the shopping. My station did not transmit unattended at any time in case you're wondering.

My setup consisted of a little 11 year old netbook computer running the current version of Debian Linux and the heart of this adventure, the software called fldigi. The computer is connected to my Yaesu FT-857d via three cables, well, two and a half. A microphone and a headphone lead that combine into the data port in the back of the radio. The other cable is a USB CAT cable, a Computer Assisted Tuning cable, that plugs into the CAT port on the back of the radio. I also used an external monitor to have my main contest screen on and used it to display the main fldigi window.

My license class allows me access to a selected number of amateur bands, 80m, 40m, 15m, 10m, 2m and 70cm. I managed at least one RTTY contact on each band.

As I described previously, my radio is set to use Single Side Band and the audio from the radio is fed via the microphone socket on the computer into fldigi that processes the information. Similarly, when I transmit, the audio is generated via fldigi and leaves the computer via the headphone socket and goes into the radio as a Single Side Band audio signal.

The information in the audio is all RTTY, a digital mode that I've described previously. The software is using Audio Frequency Shift Keying, AFSK, simulating the switching between the two RTTY frequencies.

On my screen I have a waterfall display that shows all the signals that are happening within the 2.3 kHz audio stream that's coming from the radio. Fldigi is also decoding this in real-time and showing each decode as a virtual channel in a list. Click on a channel entry and your next transmission will happen at that frequency.

If you've ever used WSJT-X this will sound very familiar.

That's the mechanics of what I've been doing.

So, what did I learn in this adventure?

Well, most of Australia goes to sleep at night, at least the ones that do RTTY. I have evidence of exactly one station on-air, and that was only because they were named in the DX Cluster, which by the way this contest allows as assistance. Since then I've found logs from at least two more stations.

Local contacts did happen during the more civil hours and in total I managed ten of them. You may think that's not much for say 12 hours of work, but that's 5 Watts QRP, or low power, RTTY contacts, in an actual contest, on a new antenna, from my shack, dodging thunderstorms and learning to use filters and levels.

You might not be impressed, but I'm absolutely stoked!

During the midnight-to-dawn run, on 40m, when there were double points to be had, which I missed out on, I did manage to hear several stations across Europe, 14,000 km away, which means that I can pretty much count on global coverage with my current setup. Sadly they didn't hear me, too many competing stations, but I'm sure that with practice I'll manage to contact them too.

The software crashed once. That's not nice. It seems to have a habit of corrupting one of the preference files, which prevents it from starting up. That's also not nice. I hasten to add that I don't yet know the source of this. It may well be a dud-hard-disk sector on my ancient laptop, rather than the software, so I'm not assigning blame here.

Getting started with fldigi is an adventure. It's not point-and-click, nor plug-and-play, more like running a mainframe whilst cranking the handle, but when you get it to fly there's lots to love about this tool.

Other things that worked well were that I'd spent some preparation time getting the keyboard macros right. These are pre-defined bits of text that you send as you're calling CQ and making a contact. They're a whole topic in and of themselves, so I'll skip past the detail and just mention that I was very happy with the choices I made, gathered from years of voice-only contacts, reading RTTY contest information and looking for exchange details.

From a technical perspective, I used both contest modes, "Running" and "Search and Pounce". Running is when you call CQ, Pouncing is when they call CQ. The running was by far the most successful for me. I'm not yet sure if that was a reflection on how much I still have to learn about levels.

One thing that I can say with confidence is that there's absolutely nothing like having a wall of RTTY signals to learn how to make sure you're actually decoding something useful. I spent a good couple of the wee hours tuning my levels.

I would like to thank the stations who came back to my call and for those who tried without me noticing them.

I had a blast.

I'm Onno VK6FLAB