Dear Quad Doctors
Noticed strange behaviour with my quad. With Version 2.6 , Logs were not working, presumably due to the dataflash issue. Now with 2.7, I notice large magnitude GPS noise.
Background: From logs (in May back at v2.5.5) I notice smooth GPS graph and log below:
Now, with V 2.7 I notice noisy GPS signal , flying in my usual flying field, with the graph abut the same scale.... see log file and graph below:2012-07-29%2021-23%203.log
I think the noisy " sawtooth" position is driving the navigation PID crazy because the quad is a bit twitchy and RTL will not land. Could I have a faulty GPS?
Setup
APM2.0
GPS: MediaTek MT3329
Here is the flight above, (my latest flight ) at the field shown in APM Visualizer 1.3.4
zig-zaggy!
Any ideas?
Replies
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
I've noticed the same thing, and I noticed a couple of others have too.
Dan