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Permalink Reply by Dan Gray on July 31, 2012 at 7:47pm

I've noticed the same thing, and I noticed a couple of others have too.

Dan

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Permalink Reply by Bob Roach on July 31, 2012 at 8:15pm

See log file from this afternoon where I took my quad for a car ride with motors on but without props so no vibration. If you open log in APM visualizer, you can see quad is pitched up because it's on my  car back seat.

Also attach a kmz. 

I think gps is very jittery!

Attachments:

• 2012-07-31 13-05 4.log, 293 KB
• 2012-07-31 13-05 4.kmz, 37 KB

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DeveloperPermalink Reply by jasonshort on July 31, 2012 at 11:15pm

The jittery GPS is not really a problem. The GPS is run through a lag filter to deal with the MTEKs almost 1.2 seconds of lag. This is only used to judge things like are we there yet? If you are flying home at 6m/s you will overshoot home by over 20feet in RTL with an MTEK.  This filter prevents that. It's not used to judge speed which is the main thing you're complaining about with jitters. It also only works in XY and not Z so it wouldn't have anything to do with landing.

One issue is the logging should use the straight GPS output and not the filtered output.

Try and lower your nav_P if you have jitteriness in the air.

Jason

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Permalink Reply by Bob Roach on August 1, 2012 at 4:28am

Thanks Jason.  I'll try lowering Nav_P. For the jitters.

I'm still wondering why I got smooth  GPS graphs in May but noisy graphs in July. Could this be a problem with my MTEK?  Or perhaps there  were changes to logging  between v 2.5.5 and 2.7 so I'm now seeing unfiltered GPS  with 2.7 and  the filtered output with 2.5.5?

Bob

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Permalink Reply by Jani on August 30, 2012 at 6:54am

Hi Jason! How this lag filter actually works and is it somehow adjustable? I see about twice bigger jitter in latitude direction, could it be because i live in north hemisphere [Finland] ?

Regards Jani

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