Good morning everyone,
During our testing yesterday with the Neo3 GPS as position source, we had an odd situation that sadly we do not know how to reproduce. We had a drone flyable for days with this system after following the steps for configuring it. We never enabled the parameters for configuring it (SLCAN interface), and suddenly yesterday the GPS stopped working. It was not that the Arducopter did not detect the GPS, it was that suddenly it stopped detecting satellites. Curiously, what worked for us was to reflash the 4.1.0-beta3 firmware and upload exactly the same parameters; literally, we saved the parameters in a file before reflashing, and after that we upload them again.
The particular thing is that we had a couple of times exactly the same situation with a U-blox FP9 based GPS using the 4.0.7, and the solution was the same in some cases. In some other cases we needed to completely reset the GPS units using the Ucenter. My question, and I need to read the AP_GPS code, is if there is any kind of configuration or calibration that is performed only after a fresh re-flashing that never happens again. I think that can shred some light on what can be the issue.