In the test below the drone never moved from its grounded positionu. 3dr Ublox standard GPS.
The picture shows a solid satcount = 8, gpshdop = 1.2 and the drone apparently flying all over the place. The track varies by about 35 meters--way beyond 3-6 meter accuracy.
Do I have a bad GPS? Is there a way to tune a GPS? Is there anything else I can try to troubleshoot the problem?
Needless to say, loiter is a disaster and auto-land isn't usable.
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I hope someone has an answer for you.
I have the same issue under trees and near buildings. I can basically never rely on any auto hold type mode when among buildings or trees.
Once I get up a couple hundred feet in the air, it does hold position surprisingly well. I recorded video of fireworks once, and was hovering in one spot about 100 meters up for about 1/2 hour, and it is just a single dot on the Mission Planner map.. maybe a meter drift that entire time. But that same copter flying low around trees for fun, if I switch it to hold, it will drift badly.
This is the case w/ several GPS's. (some are worse than others).
I've been told it's normal, and due to multipath.. But then other people say they don't have the same issue..
And, I hike and have been out in the mountains under trees, near large rock surfaces, and my hiking path w/ the garmin is always right on track..
Hopefully there's a solution..
Thanks Scott, I'll try this again in an open field. Multipathing sounds like it might be the answer (although my iPhone is rock solid under similar conditions...argh).
I had a spectacular tree-house-deck collision due to faulty voltage calibration triggering a battery failsafe which I had set to RTL which got a bad read from the GPS. I have it set to ascend 100' prior to RTL (in case it loses contact behind a building) which it will do if it's not within 10 meters of the launch point. Suddenly my drone nicely hovering at 5' sounds the panic alarm and starts to fly up into the trees. I pull the throttle all the way down to no avail. I watch helplessly as it engages the branches, careens on to the roof and crashes hard on the deck.
Lessons learned: Don't enable battery FS until voltage is reading correctly, don't fly in the back yard, consider RTL carefully.
The joys of DIY!