"prearm: 3D fix need" but 3D fix is show

ArduCopter
1

Hi Folks,
i have weird issue and i cannot solve it.
i build new platform witch is H Copter, i have FC Matek F765 witch arducopter 4.0.3 and GPS module Drotek zed f9p on board, on the ground i have second zed f9p to get RTK. like a telemetry and rc signal i use rfd900x.

I done few test fly and everything was ok, but sudenly after change battery to next flight i get error “prearm: 3D fix needed”, at the same time my GPS onboard shows about 20 satellite and 0.5-0.6 HDOP.
i am fighting with that issue few days. i change firmware in FC to older, bring all settings to default - in FC and in GPS module but there are still has the same issue.
anyone know what go wrong?

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2

Hello,

This message is missleading and we are trying to fixing it.
The GPS is fine, that the EKF that isn’t settle yet… check on your MP picture it is red

3

Hi khancyr
behind the “red” EKF is hiding: velocity_horiz off and pos_horiz_abs off
do you know what that’s it mean?

in quick research i see that corresponding to compass error but i don’t have a compass onboard.
to be honest i start with compass hmc5883l onboard but my platform generate big interference, compass/motor calib shows above 35% interference and i decite to disconnect compass. after desconnected compas i make 3 flew and everythind was fine

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