Explanation of RSSI values

I looked at the documentation, but cannot find any explanation of all the RSSI values displayed in the Telemetry and RC windows.
Can anyone explain it or point me to the relevant docs?
Also, I would like to know what is the correlation between the values displayed on the radio (typically 50-80) and the values QGC displays.

Hi @rsilk, that’s a good question! I remember there was recently some discussion and fixes around this but I don’t remember the details. Have a look here:

So I think the takeaway is that the MAVLink message got changed so that the RSSI values are scaled from 0 to 254, see: https://github.com/mavlink/mavlink/pull/1083

However, this might not be implemented correctly in PX4 yet: