Make FGFS read and use the RDF data

[hbeni]

Make Flightgear able to parse the information and , if tuned to the frequency, make ADF needle move accordingly.
Note: this may be impossible if the property is tied to C++ space (which i assume); this then would need changes in the fgfs core. A Proposal could be another property that is investigated from the RDF/ADF C++ code and also taken into account.

We should look into this once mumble 1.4 is out and we have some pilot feedback on the overall system.

(Followup on the RDF feature #8)

[hbeni]

The prop in question is instrumentation/adf[0]/indicated-bearing-deg.

The idea might be to send the ADF in the protocol file as separate radio, make it receiving, but do not show it on the statuspage in order to not confuse people.
A generic and probably nice solution would be another boolean flag sync=true in the radio, which when set to false will prevent synchronization to remote clients.

[EDIT] just tested it with the C172p and the C182s: The property is writable and keeps the value.
That means we can push back the RDF value into the FGFS protocol and implement a simple nasal script that parses this and tries to push the needle into the proper direction when an RDF signal is received.

[hbeni]

Digged into this a little more.
It seems FGFS is currently not capable of assign the sending client port as listen port dynamically.

Asked on the forums: https://forum.flightgear.org/viewtopic.php?f=36&t=39073
If all fails, we might probably assign a fixed port and overwrite the identites UDP client port setting in the plugin using the UDP_TGT_PORT=12345 feature.

[hbeni]

Implemented and tested with the C182s and C172p :)

Seeing the needle move when some fgcom-mumble client sends on the ADF frequency move is rather cool :D 😎

[edit] Btw, the audio that is transmitted on the net (ident morse code, or radio program) is bound to the ident-audible property of the ADF. It ident is on, audio can be heared. Ident is supposed to be set from some audio panel in the aircraft.
I used default properties, so this should work with any aircraft - it certainly does with the two tested ones.

Funny real life example on tuning to an ordinary AM station: https://www.youtube.com/watch?v=HKXZZXoLMO8