Mark, N8MH noted:
The 437.024 transmitter antenna configuration on AO-16 is Left Hand Circular polarity (LHCP). The receiving antenna on the bird is a 1/4 wave vertical whip.
This whip operates against the body of the spacecraft as a "ground plane"; however the spacecraft body is a cube 22 cm on a side (you can see a picture at http://128.54.16.15/amsat-new/satellites/satInfo.php?satID=11&retURL=/sa... http://128.54.16.15/amsat-new/satellites/satInfo.php?satID=11&retURL=/satellites/status.php). This is about half of the quarter-wavelength you'd like to see for a proper ground reference, so the actual pattern undoubtedly has some weird nulls.
The fading is quite dramatic, which means the bird is spinning/tumbling, or some combination. We could never hear this before on AO-16 when it was transmitting its normal PSK signal, since we didn't hear the effect of fading on the uplink in this mode. Now we hear it, loud and clear!
It does take an uplink signal that is pretty close to on frequency (145.820). Adjusting for Doppler is helpful thing on the uplink.
The receiver has a 15 kHz wide crystal filter with sharp skirts. So if your NBFM xmtr is set with a ±5 kHz deviation, you may well find your signal hitting the filter "walls". You may get better performance if you crank the deviation back a bit.
73, Tom