Very strange dual GPS behavior

This aircraft flies pretty good, but drifts much more than it should even with an excellent GPS lock. It’s using dual m9 GPS on the CAN bus. As you can see in the screen shot, the position solution has a weird saw wave look to it. Any idea what might cause this? Here’s the log

13" quadcopter 3kg AUW

Please attach flight logs (.bin file) !

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Hello, I did. If you look you’ll see the “log” text is a link to the .bin file. Cheers :smiley:


Oh, sorry for not noticing it, will check it now! Thanks!

Are your compasses/compass calibrated? Try connecting one gps, then the other, does it happen only when both are connected, but doesn’t happen when only one is connected?

Yes they are all properly calibrated. This is a test unit from my company and I have a lot of flight hours on it without any issues. The client who it borrowing this unit reported some strange drifting in loiter and this is what I saw in the log. I’ve done a lot of log diving over the last four years but haven’t ever seen anything quite like this. I will say I’m running dev 4.1 and have GPS affinity turned on. I wonder if this is some sort of glitch? @tridge

I see your problem you only need 1 GPS. lol sorry… yea that saw is odd. Looks like all your flight modes are set to 0?

Yes we use solex to set all our flight modes via mavlink commands.

I think the jumping position is just a visualisation issue in an older version of the Mission Planner. This is certainly fixed in the latest beta and probably the latest stable as well so perhaps try updating MP from the Help screen.

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This visualization is from Dronee. Possibly an issue with that?

@vosair sir please check mission planner beta update. then you will get right GPS track. this because of version conflict. choose beta mission planner.

thanks and regards

This plot is from, not MP.

Must be:

Dronee, Pfft…

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That would certainly make sense! Showing all the 2 GPS plus the virtual Blended GPS.

Yea, looks good I would say. But i don’t have GPS modules that good :slight_smile:

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