Apologies for resurrecting an old thread, but after a few months of tinkering I made some progress. My main issue was finding the correct combination of SDR and PC; my rtl-sdr’s have too low sensitivity, while the airspy and USRP B200 work fine, but won’t work with an RPi3 (airspy) or are needed for S-band (B200). I think I’ve now solved the sensitivity problem of the rtl-sdr’s by using an LNA (the wide band with the FM notch from the no-rotator setup).
Initial results from this evening look promising:
https://network.satnogs.org/observations/112784/
https://network.satnogs.org/observations/112786/
The LNA raises the power levels out of the -100 to -50dB standard range of the gnuplot waterfall script, so I created a matplotlib version which computes the power levels from the data, hence the different waterfall plots. For now these waterfall plots are created manually and placed back into the upload directory, but I’ll see if I can adapt observer.py to generate the plots automatically.
Right now the rtl-sdr gain is set to a low value of 7.7dB, as that worked well with the gnuplot script. I’ll try to run some tests with higher values to see if that improves the sensitivity.
