Still waiting for my amplifier so things are fairly stable on the message front.
Today my stats show one hit out at +300 miles, to the south, and on a line that I only usually reach 180 miles. Now I’m assuming that it is just a spurious signal, but is there any way I can prove or disprove it? I’m running collectd graphs but that only shows a max adsb range of ~ 200nm for the 24 hour period.
If you know what the aircraft was, you could look for corroborating data e.g the flight track as reported on FA. Most of the time it is just bogus data, either a bad position from the transponder or the receiver garbling a message, but sometimes you do get real signals at improbable distances if the atmospheric conditions etc happen to be just right.