Hi Paul,
Thanks for the interest in the PSK31 transponder, as Bob already pointed up, the downlink audio spectrum is shared, so at 280Hz and 374Hz are PSK31 beacon tlm streams from camera board and transponder board respectively. Then every 4 minutes the SSTV signal is present so if you plan experiments in PSK transponder, try to stay between the beacons and SSTV. Description of modes you can find at https://github.com/alpov/PSAT-2/blob/master/README.md
We would be glad to answer any questions about this experiments.
We are still awaiting for any positive confirmation of downlink signal at 435.350MHz as for us it is still below horizon. Any audio recordings, IQ data or at least pictures of reception would be welcomed.
73! Tomas OK2PNQ and Ales OK2ALP