GPS Unhealthy

I am just preparing a custom drone using navio2 for its first flight.

I’m running ardupilot 4.1.3 downloaded from the ardupilot site (but the default 4.0.3 has the same issue).

I’m using QGroundControl as the GCS.

The GCS is reporting 19 satellites and a GPS 3D fix - i.e. all seems ok. I’m using the GPS antenna supplied by Emlid and its mounted well above the rest of the electronics

When I switch from Stabilise to Guided mode the system reports that the GPS is unhealthy and/or it cannot get a good GPS position.

I’ve had a look at

but I’m not sure if I should be deep diving on this or if there are some other recognised issues.

The implication from above is that navio/ublox cannot deliver the GPS data update rate that ardupilot expects with the default GPS settings. Is this the identified problem?

Any ideas as to how to debug or if people have seen and resolved would be most helpful.

Not sure if this is fully resolved (more testing required) but I have removed the issue with the following two changes:

GPS_RATE_MS - 8Hz
GPS_NAVFILTER - Pedestrian

Hi Foeg,

Thanks for sharing the solution that works for you!

This is a really valuable finding. We didn’t get any reposts on this recently, but if someone faces this issue too, it’ll be worth trying the settings you shared.

Nothing new with this one:
There are multiple reports about this problem. Others and myself have crashed drones because of it.
Essentially there is an underlying problem in the way the data from the GPS module is processed (or in some case not).
You will find various reports about this if you search on here
The various solutions include:

  • Changing the GPS receiver settings in order to limit the satellites it uses and as such providing more reliable data on those few it then has to process.
  • Lowering the update rate of the GPS data stream (similar result as above)
  • Installing a second GPS receiver which can be used as a fall-back unit. ( In fact I’ve discovered it is more reliable to use the second GPS receiver as the main unit and the Navio build in unit as the backup)
  • Using a more reliable flight controller as many others have done due to this problem.
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