The SDR earthquake will change our hobby forever

Foundations of Amateur Radio

In the early 1990's when I was a broadcaster I would come into the studio and prepare my show. That involved hours of preparation, but on the technology side it involved vinyl records, reel-to-reel tape on open spools, looped tape on cart, running edits and razorblades. If you're not familiar, a running edit is where you're playing the tape at normal speed and you hit record at just the right moment to replace the content. Of course that also requires that the thing you're recording is synchronised. Imagine yourself with four hands and three ears and you'll have a good idea. Razor blade edits required that you mark the tape where the audio started, chop the tape at that point and stick it to another piece of tape. The joy of having sticky tape, razorblades and audio tape strewn around the room and hoping that the tape didn't let go when you transferred the audio to a broadcast tape.

If you wanted to play a song at the right time, you had to start it by putting the needle on the record, spinning the platter until you heard the song, then stopping the platter, winding back half or three quarter turn from where the audio started, depending on the speed and torque of the turntable, and then when you hit play, you'd have about half a second until the music started.

At the beginning of the 1990's that was how it was done.

Then compact disc came in and we could cue up a song and hit the go button and get almost instant sound. You could change tracks at the turn of a dial. Vinyl records were phased out pretty quick.

In 1993 I switched radio station and instead of reel-to-reel we used DAT, or Digital Audio Tape. It had the advantage that there was no discernible loss of audio quality as you copied material, but there was no editing, since the bits on the tape needed to be aligned and you just couldn't do that with most of the available gear. The start-up delay was horrendous too, several seconds if I recall. A lifetime of dead air if you got it wrong.

You might be wondering why I'm going down memory lane like this?

The reason is that something changed, fundamentally, almost overnight.

In 1995 Microsoft launched Windows 95. It was in August and as the local computer show I organised a competition to give away a copy of Windows 95. I edited my competition stinger, a 15 second and a 30 second promotional audio segment, entirely on my computer. Using SoundEdit 16 on my Macintosh computer I could overly tracks, add voice-overs, move sound tracks around, add dozens of tracks, change the left and right channel independently, amplify or delete specific beats, all things that were completely impossible using the gear in a radio station at the time.

When I brought my stinger into the station managers office on my laptop computer, the earth shifted. Overnight everything changed. At that point radio stations around the globe started the race towards entirely being run from hard-disk. The digital revolution hit broadcast audio.

That's almost a quarter century ago, but that change cannot be overstated.

I think that in amateur radio we're looking at the same kind of change with the same level of impact.

Today you can go online and buy a NanoVNA for less than a hundred dollars. This device, a touch-screen driven tool, allows you to measure electrical circuits. For example, you might connect an antenna and measure the impedance of that antenna. If you connect a reference antenna to the second port, you can even measure radiation patterns.

Think about that for a moment.

You can measure a radiation pattern. That means that there is something that radiates.

Does that sound familiar?

Perhaps like a transmitter?

So this NanoVNA is essentially a transmitter and receiver in one box, currently runs up to 900 MHz, but the next version is already in the works and it's slated to manage 3.5 GHz, for the same amount of money.

So, a 3.5 GHz transceiver for less than a hundred bucks.

If you look at the internals of a NanoVNA, you'll notice that it's got much of the same bits as a software defined radio, because it is a software defined radio. Thanks to modern integration, at a component level it has significantly less complexity than the early 1980's microcomputers I grew up with like the Commodore Vic 20.

Yes, I know, it's not quite a radio. There's different filtering, different software, no audio input, or output for that matter, no Morse key, it doesn't do FT8 or some other fancy mode, but guess what, it's all software. The parts of this device aren't complicated, they're cheap, simple to program and I don't think it's going to take long before we see a new explosion of software defined transceivers that are begging to be used by radio amateurs around the globe.

We live in exciting times would be the understatement of the year.

I'm Onno VK6FLAB