4 Nov 2016

2m JT65B on 144.166MHz

Since about 1900z I have been on 144.166MHz using JT65B. I am doing a test with G3WKW but if anyone else wants to listen and report to PSK reporter than would be appreciated, of course.

UPDATE 2002z:  G3WKW (133km) spotted me 36 minutes ago on 2m at -24dB S/N! Thanks Bob.

UPDATE 2035z: Now G6AVK (77km) has spotted me on 2m. Thank you.


Bob G3WKW said...

There were visible spots of around 20 seconds duration in about 75% of transmissions early on. I thought my newly reassembled transverter had failed so switched to the FT897 for transmission but then discovered a switch in the wrong position so I had been keying the UHF transverter while attempting to drive the VHF! Anyway went back to the transverter later and was still being copied. We should try some of the fast JT9 modes which are available in 1.7. Not sure how well documented they are.
For serious communication we would need an ARQ mode. ARDOP comes to mind but I am pretty sure it will not work on VHF through an SSB channel because of frequency stability and tuning accuracy. Are the bursts strong enough to support an FM signal for a few seconds, and will the data rate ramp up fast enough before the channel fades? That would be the normal recommendation for ARDOP at VHF. What surprised me was the lack of visible Doppler on the bursts of signal that I saw. My observations on GB3VHF sees a lot of Doppler.

Bob G3WKW said...

Found the table of JT modes http://physics.princeton.edu/pulsar/K1JT/wsjt_modes.txt with further documentation at the bottom of http://physics.princeton.edu/pulsar/K1JT/Fast_JT9.txt

Bob G3WKW said...

Well it looks like it wasn't a bad choice of frequency! 144.165 is now recommended, and 432.165 and 1296.165 see page 71 of December RadCom received today. I have now modified both my transverters to have separate TX and Rx ports so I can manage crossband duplex operation. Hoping to hit FO-29 sometime.