Pgps switches to Atti mode with 12 sats locked in

Nov 12, 2015
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my question is why do I have a faulty controller ( it's the same controller that was bound to the lost drone )
im not sure how a controller makes a compass error. probably doesnt.
Feb 20, 2020
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meta from my experience I have a 100% working and never crashed phantom 3 standard and a phantom 3 pro both experienced compass errors due to heavy magnetic interference. That was about 2 days in a row and heavy equipment was nearby after it was done no compass error and no magnetic interference so what was it I'm curious cause I believe machines factories even heavy usage of buses I've noticed magnetic interference and when buses are gone I get no magnetic interference.
Interference is common in urban areas but it still won't have any effect on the compass.
Aug 7, 2016
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Now you know that this happened due to the environment influence. It happened twice with different drones and at gthe same place and time. The only cure is not to fly there. Or if you expect what is going to happen prepare to fly in ATTI. The first drone you lost simply because you were not aware that ATTi kicks in otherwise you could easily fly it back manually.
If nothing is wrong with the compass I would not calibrate it. Especially not in that place.
And I think that nothing is wrong with your RC either.


Staff Member
Premium Pilot
Jan 8, 2014
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I'm curious cause I believe machines factories even heavy usage of buses I've noticed magnetic interference and when buses are gone I get no magnetic interference.
I fly near very large steel constructions all the time.
You'd have to be within just a few feet of a bus for it to affect your compass, probably <10 feet from a steel factory.
Flying at normal heights, nothing on the ground will cause compass problems.
Sep 7, 2017
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Hi there,

A suggestion...
Take off the top lid and check if the GPS electromagnetic insulation (grey layer with copper film in it) is in place and well adhered to the top shell. On P3S the insulation extends a bit along the arms. While you are there you can unscrew the motors and twist the cables 2 or 3 times by spinning the motors around
( this will reduce the electromagnetic field the wires generate) and check all connections and if the "motherboard" is well tightened (it has 4 screws with rubber washers).
Do an IMU calibration followed by a proper compass calibration. Proper compass calibration is best in a field or forest or in a big park at least. In a park, you still don't know what is under the ground.
Learn to download the DAT files from the aircraft, do not waste your time with the phone logs, they are partial logs.
Download DATcon and CSV view and learn how to use them. Both are free.
Do 2-6 flights with harder than usual spins around and altitude changes, as well a windy day will work your drone harder. Stay in the safe distance, you do not need to go far. Download the DAT files for the flights, convert them with Datcon and open them in CSV view. Open magnetic mod view and your compass calibration should show about 1500 (I think the measuring unit is called Tesla) In a well-calibrated compass with no other issues your values should not vary much from plus-minus 100. The setpoint is 1500. If you get over 500 +- do not fly Litchi missions. Will go like the first drone, sooner or later. As well, have a look at GPS satellite number and GPS signal quality.

A general safety rule on Litchi missions. Do not take off in auto mode by starting the mission from the ground. Go up manually, do a couple of spins around both CW and anti-CW, best combined with a hard ascent. and a forward-backward acceleration. If all looks good (no Atti mode auto switch) press play and the mission will load up and start just as usual. The more time you spend flying around before going into the mission, the better. From my experience, GPS or compass errors do not show up always immediately.

Good luck,

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