Foundations of Amateur Radio
Every now and then you come across an idea that throws you for a loop. It comes seemingly out of nowhere and once you've seen it, you cannot unsee it. It's a lot like a 1929 painting I like called "The Treachery of Images", also known as "Ceci n'est pas une pipe", or in English, "This is Not a Pipe" by Belgian surrealist painter René Magritte. If you're not familiar with it, it's a painting of a pipe, and by being a painting, it's not a pipe. Obviously.
Before I go into the idea that rocked my world, I need to set the stage a little.
There are several modes I've discussed before, WSPR, or Weak Signal Propagation Reporter, FT8 or Franke-Taylor design, 8-FSK modulation and plenty others.
Each of these modes has one thing in common. They require that all participants are using the same time. That is, both sender and receiver need to agree on when "now" is for this to work.
A WSPR signal takes 110.6 seconds, every 120 seconds, starting on the even minute. It requires that the transmitter and receiver agree on the time within about 2 seconds.
An FT8 signal takes 12.6 seconds within a 15 second window. It requires an accuracy of about 20 milliseconds.
These timekeeping requirements are pretty easy to achieve in a modern network connected computer. You turn on a thing called NTP, or Network Time Protocol, point it at an appropriate clock and off you go.
If you're not connected to the Internet, then things get squirrelly pretty quickly. You could buy yourself a GPS, set up a link between the GPS and your computer, run some software and use the GPS clock to synchronise time on your computer.
Of course, this requires a GPS, a serial cable, software, configuration, battery power to keep the GPS running and probably a couple of other things. I've never done this, but given what I'm about to share, I don't think I ever will.
What if you used a WSPR, or an FT8 signal, from someone else to synchronise your clock? If you've ever launched WSJT-X, you'll have seen a column marked DT, that's Delta Time, or the difference in time between the clock on your computer and that of the transmitter.
If you could read the difference and use it to adjust your clock, you'd be in business.
Charles NK8O pointed me to a GitHub Gist with a single little Python script, written by Peter K6PLI. It updates the clock on your computer using the Delta Time from WSJT-X.
I'd point you at the script from here, but 3a730575, and 24 more characters, and that's just one element of the URL, doesn't run quite off the tongue, so I've cloned it into my VK6FLAB GitHub repository where it's called wsjt-time-sync. I added Peter's description to the ReadMe file, but I can take no credit for the effort, or the idea, that's all Peter.
So, synchronise your clock using the signal that you're trying to decode. Seems pretty obvious now, but that was a brand new notion for me.
Of course now I'm excited and wondering where else I might use this.
Let me know if there's more to this that tickles your fancy.
Also, just because I know Charles will poke my eye out with a Morse key if I don't mention this, you could use this script on your next POTA, Parks On The Air, or WWFF, World Wide Flora and Fauna activation, or anywhere else you go portable to make some noise.
I know, right, Charles, using FT8 instead of Morse Code, what's next, the end of the hobby? I'll tell you a secret. From time to time, he even uses his voice!
I'm Onno VK6FLAB
