Thursday 4 June 2020

Real-time propagation

I've been thinking some more about John, EI7GL's recent activities, and a little about my own, with QRSS (slow Morse) transmissions, and what they can reveal about propagation.

John rightly notes that QRSS is a very useful, visual way of keeping track of propagation, and how it changes in real time.

A QRSS signal, showing propagation changes over several seconds.

There is a problem with using QRSS, though, and that is the tiny number of people transmitting it, making gathering data rather difficult.  This number isn't very likely to increase much, because one has to build a fairly involved kit to send QRSS.

This problem doesn't afflict WSPR so much, not least because you can buy cheap 'plug and play' WSPRlite units, or just use a transceiver and computer. As a result, there are many more WSPR stations on the air than QRSS.

So, I got to thinking: why not just use Argo, the QRSS-optimised spectrum analyser, to display WSPR signals instead?

So, I tuned to the 28MHz WSPR QRG, and adjusted the frequency scale on Argo to ~1400Hz. Soon, enough, a nice example signal appeared, nicely expanded in frequency and time, such that quite a lot of detail is visible.

A 28MHz WSPR signal, also showing propagation changes, visualised in Argo.

OK, you can't directly read the callsign using WSPR and Argo as you can with QRSS.  But there are simple workarounds, such as multiple audio streams, one feeding Argo, the other JTDX, so that callsigns can be matched with signal traces on Argo.  Or, just becoming familiar on JTDX with who is transmitting at which frequency, and then applying that to Argo traces.

Altogether, using WSPR in this modified way is quite interesting, and a lot more productive than waiting for the small number of QRSS signals to appear or, as is often the case, not appear!


1 comment:

Paul Stam PAØK said...

Hi John, I did some QRSS in the past, but as you say, not to much activity there. Another problem is I can't decode the morse as I see it on photos. I need to hear CW. When the speed is to slow I have problems to copy. WSPR is for me the best option for a beacon function and watch propagation. 73 Paul