Yes, it has been tried in SSB (i.e. linear receiver), mostly for some PSK31 tests. PSK31 signals (at whatever doppler is applicable) would them modulate the NBFM xmtr. So you tune your favorite PSK31 demod on the noise output from your 70cm rcvr. Downlink doppler is irrelevant. Drew/Gould should offer comments, but I believe some signal were copied by no QSOs made. The stations were (as I recall) running ~100 watts out from a typical HF xcvr.
Right on Tom. Tried, didn't work well at all. Bruninga has tried this on both PCsat-2 and RAFT with similar results although that might be more due to equipment.
Bill, a decision was made after launch that we wouldn't risk the SQRX being possibly damaged by the UHF transmitters on AO-51. The risk is probably small but is certainly real, plus there are hurdles to commanding with the UHF transmitters off. Lots of merit in your idea, but also risk. I'm attaching a similar survey done with the Received Signal Strength Indicator (RSSI) feature of the SQRX on 2m, that Tom will eventually talk me into publishing ;-)
73, Drew
