A quick play on the bench with serial output.
I have had a busy weekend with little time for FrSky fun. However I have got some HEX dumps of the serial stream from the TX module to post up.
If you don't have a HEX EDITOR to open the LOG files with you will see just rubbish on screen (notepad etc will try display hex in ascii characters).
To see the raw hex output open the log in something like this.
If you don't want to do that, then look at the PDF's, but they are not the whole file, just a page.
Frames start with FF FE, there are 10 bytes total. Signal level can be seen varing on the 5th byte of the second log file. I attenuated the signal with a piece of steel pipe over the TX's antenna to vary the level.
00h seems to be the value for strong signal/low errors, the value goes up as errors go up (signal going down).
The 'Range Out' warning beeper in the TX module started beeping, so it was really cutting the signal down. The RX end was also around the other side of my house BTW, my shed door was shut too. The system seems quite sensitive based on testing other brands the same way.