Wondering, is it possible to keep a log file on the SD card of all the aircraft seen? I used to run my Pi with rtl1090 and used a laptop to store the data from the log files generated by it. Is it possible to just write to a file on the SD card? This gave reg number, callsign, aircraft type etc. It was handy for the likes of search and rescue and some military that do not broadcast all the data required for position etc.
It is possible to keep a log - I have modesmixer2 running on a separate machine as that has the ability to write to a basestation.sqb file. It records quite a bit of data, including the times and positions the aircraft was first and last seen. It doesn’t record the exact path, but gives an idea. You can use virtual radar server to query the database and produce reports. VRS can also write to the same database directly, but then you need to have that running continuously and it isn’t as easy to get working properly on a linux machine.