fadump1090.sh --PPM switch?

Did anyone ever figure out if the value is either positive or negative? The FA Stick Pro in SDR# (on my PC) shows a PPM offset of 75 for me… in fadump1090.sh i’m using a positive value and it seems to work better than the negative value.

I’m using the Pi 3 Mod B with the Piaware 2.1.5 image…

Stats look good from what I can tell but just wanted to know if anyone knows for sure what the value is suppose to be…



It can be either positive or negative depending on your dongle. The value you give to dump1090 is just passed to librtlsdr, so whatever sign that librtlsdr wants.
I don’t know what convention SDR# uses.

SDR# for the PC wants a positive value which brings it back to a zero offset.