Multiple Simultaneous FT8 QSOs using a Single Radio

Trying to fall asleep all sorts of wild ideas visit my had. Yesterday I was thinking about FT8.

When we turn on the speaker during receive we hear multiple radios transmitting on different sub-frequencies. To us it sounds like a chorus of whines at different tones. The app then decodes them all and we see multiple QSOs in band activity. When we transmit, we pick a sub-frequency and send out one of those whines:

Hmmm. What if we don’t stick to a single sub-frequency and instead sent out multiple tones at the same time? Well… WSJT-X will not to that*, not without another WSJT-X copy. As I accidentally learned before, you can’t run multiple copies of WSJT-X on the same computer so we’ll try to keep copies unaware of each other’s existence. Welcome virtualization.

I used free Oracle’s VirtualBox and a free evaluation copy of windows virtual machine to run another copy of WSJT-X. The only way to make virtual copy use the soundcard linked to radio was to temporary make those audio devices defaults for input and output in Windows audio settings. Behold the multiple simultaneous QSOs:

Only primary copy of the app is in control of CAT/PTT so transmission in virtual copy must be initiated in the same timeframes. I set PTT method in to VOX in virtual copy so it doesn’t try anything funny. Also important to make sure the parallel transmissions are done on different sub-frequencies.

BTW: nothing stops us from running more than two copy with additional virtual machines if you are really fast with your mouse.

It is interesting to see the difference in the spectrum at the time of transmission while using a single copy (left) and two copies of the app (right).

Well, that was fun, but it feels like a bit too much stress to operate. I’m sure some competitive contesters will find this more appealing that it is for me. As far as I can tell there is nothing FCC would not like about it, but I’ll withhold my judgment as to whether this represents an unfair advantage in a contest.

*Later today I learned about the way to run multiple copies of WSJT-X on the same machine with additional command line parameter “name”:

WSJTX.exe --rig-name "rig1"
WSJTX.exe --rig-name "rig2"

This should make it easier to experiment with parallel QSOs.

Multiple Simultaneous FT8 QSOs using a Single Radio
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