“I’m curious whether the sample rate has an impact on the quality of the received results, because generally the sample rates for small satellite signals are around 48k, 57.6k, and 66.56k, which means they are below 250k. In my ground station, I tried lowering it from 2.048e6 to 1.024e6 and then to 250e3, and it seems there was no difference in the received results among the three.
By lowering the sample rate, I believe it reduces noise, more focus, reduces the performance load on the SDR, and the SDR appears to run cooler. What do you all think?
Nope. As far as I get, the rtl-sdr only needs lower USB bandwidth and less machine power on lower sample rates and I find the mirroring the least at 2.048 msps.
On the other hand, like Airspy Min in 3 MSPS and with decimation indeed the SNR improves, I tested that with L-band satellite decoding, Aero, and I got up to 6 dB better SNR when using decimation to get to just a bit more as the transmitter bandwidth.
I run my station @250e3 for a day, and I don’t see any CPU load decrease. satnogs_fm.py and likes take about 55-60% CPU (on a Raspberry Pi 3B) and sdrplay_apiService about 12-13%.