I'll bring the APRS board up later this week.
Yes, I am a ham radio operator, license KD5FTN.
The APRS Transmitter is designed to be a stand-alone redundant location tracking mechanism, totally independant of the APM autopilot.
The APM autopilot radios will maintain a continuous telemetry connection with our ground-based radio. Default "air rate" is 64K, but we can reduce the data rate offset for a weaker signal and get more range. Additionally, I can use my more-sensitive ground-based radio (RFD900), which has diversity antennas. We can use high-gain antennas and aim them appropriately. (Or get fancy and build an antenna tracker)
We'll likely also want to add a small RC receiver to the payload which we can use to both manually fly the glider and/or manually activate the nichrome trigger, if we have an RC signal.
So, we can have three potential ways to trigger the wire cut, but all dependant;
- Scripted mission, wire cuts automatically upon reaching altitude (Automatic)
- Do_Relay command sent manually via Mission Planner (Dependant on Telemetry radio link)
- Switch activated on RC transmitter (Dependent on RC signal being received).
The good thing is, bot the telemetry and RC radios will have RSSI telemetry to let us know signal strength, but we won't know real-world range until we actually go fly this thing.