Telemetry will not reconnect if lost for an extended time

ArduCopter Copter 3.5
1

I’m running the latest code on a PixHawk(1). My telemetry is through RFD900+ radios set to error correction, retransmit and Mavlink protocol.

As long as the radio are within range, it all works fine. But if the radios lose contact for an extended period - say 10 minutes, they refuse to automatically reconnect regardless of how close I put the radios. If the telemetry is lost (radios go out of range) for a short time, it will reconnect fine. But if the radios are out of range for an extended period of time, they will not reconnect.

When running a long mission (8 KM - not in the USA). I lose telemetry contact after about 3 KM. The radios do not reconnect even when the craft returns and is no more than 10 M from the base station.

Does the PixHawk have a transmit buffer problem? When the transmit buffer is full, does the FC quit trying to send data? Has anyone else reported this problem?

2

I found the issue. I was powering the RFD900+ from the PixHawk telemetry port, and the connecting wires were of fine gauge (28ga?). I had a 6.3V 10,000uF capacitor soldered across V+ and GND on the RFD900+ because I figured it would have high peak currents. After I started having trouble, I 'scoped the power on the RFD900+ and found that the voltage dipped down to 3.5V for several milliseconds at a time - especially when trying to connect. I also noticed that one of the capacitor leads (of my added capacitor) was broken at the capacitor body.
So… I put on a new capacitor and added another voltage regulator to power only the RFD900+. I now give it a steady 5.4V. That fixed my problem. It increased the telemetry range a bit as well.