@sonic67 Then write receiver not Raspberry Pi please.
I’m not quite sure but yes i’ve also read somewhere the rtl-sdr chipset is indeed a limitation. Not quite sure why though
You can also watch your local skyview, if some planes disappear relatively close to you or transmit less messages their signal is probably too strong. Before and after they disappear their signal would be somewhere between -3dBFS and 0dBFS.
Especially low flying aircraft can have a very strong signal as they can be close to your antenna while they are also in the optimum reception plane.