Every time I arm my board there is a message «Unhealthy GPS signal» shown. This message dissapears after 3-4s after arming is done. There is stable 3d-fix with more then 10 satellites achieved nevertheless. This message does not appear while disarming, GPS-positioning seems to work stable with no respect to armed/disarmed status.
Matek F765-WSE under Ardupilot 4.1.7 (checked down to 4.1.4)
U_Blox M8N GPS module (with compass).
3DR radio for Mavlink connection (433MHz, 20dB power)
Parameters of U_Blox M8N has been reverted to defaults through u_center. M8N corresponding parameters set in MissionPlanner:
GPS_AUTO_CONFIG == 1
GPS_RATE_MS == 200ms(5Hz)
SERIAL3_BAUD == 38 (38400) (230 (230400) was checked also)
I also suppose that such a behavior could be a consequence of thread races. If GPS signal was really unhealthy then this message should be present all time but not for 3-4 sec at arming invocation only. I will check GPA deltas report on weekend to confirm or disprove this guess.
I was having this issue and it was driving me nuts. I would get fly-away’s that would result in crashes and unlike you I would get 3-4 Sats. I spent a lot of time trying to figure out what was happening and what I started to realize is that shielding the antenna is key to the whole thing working.
I put a metal “ground plane” under the antenna (which is mounted about 4 inches above the deck) and it helped, I got more Sats but I would get the GPS Unhealthy message after arming. That seemed to indicate added interference from the ESC’s and/or motors. I looked around for a quick fix, something that would shield the sides too, and I found this metal can. I stuck that to the top of the mast and put the antenna inside of it. So far, I’ve had good results. I’ve gotten more Sats than ever before - goes between 11-13, and for the first time I see 3D dgps instead of 3D Fix.
The can I am using is too big and looks terrible, I’ll be finding a more elegant solution soon.
Nope, not a thing plugged into the RaPi USB ports. I tipped the telemetry radio forward. I started to notice that the vehicle, sitting on the launch pad soaking up satellite signals was fine, but as soon as I went to ARM it, the GPS Signal unhealthy message would pop on the screen. After disarming, the message went away.