I have been using GQRX and Gpredict for a couple of months. They are both very
nice programs. Today Sept 1, I think that I finally have it figured out. I have
been leaving them up continuously 24-7 for about a month without receiving anything
with Gpredict and GQRX while I would always catch some telmetry frames using my Windows 10 machine, SDRSharp and Orbitron.
I think that I know why now. Today, I was able to be at the computer for several
passes of AO-85, AO-91 and AO-92 and received over 100 frames using Gpredict and GQRX. But I had to do several thinks to accomplish that. I also noticed that the Hardware Frequency reading on the Receiver Option Tab didn’t match the satellite that was overhead at the time and the kHz offset was very large. The the frequency range of the satellite above the waterfall didn’t match the frequency range of the satellite overhead.
I tried a couple of things by manually setting the correct frequency to the Hardware frequency by inputting the correct value in the Receiver Frequency box and then zeroing the Channel Filter offset value to zero then again setting the receiver frequency to the correct value. I’m using a RTL-SDR dongle for my receiver. Another observation is that it doesn’t appear that Gpredict passes the Downlink Frequency to the Hardware Frequency when the satellite becomes active by either clicking on the satellite shown on the world map on Gpredict or when is within the radio window. It would seem that Gpredict should pass the value in the update transponder database to the GQRX Hardware value then offset the frequency for Doppler from the Hardware Frequency value and then center that value in the frequency reading just above the waterfall.
I’m curious whether anyone else has seen anything similar.