I think this fits in this subforum? In Mission Planner 1.3.24, over a period of 2 hours and 20 minutes “time in air” the compass “zero” has drifted from 0 degrees to 340 degrees in a clock-wise rotation through each degree. I am trying to form a hypothesis for this behavior: thermal offset causing drift seems unlikely as it is steady rate over a long time period. The system is being powered by a 3DR 3 amp BEC with the sensor circuit for voltage and current. The APM 2.8 is driving a 3DR radio and a minumOSD, and a Ublox lea6h-0-002. Current readings in the HUD indicate current nominal consumption at 2.6 to 3.1 AMPs, about maxing out the BEC. By the way, the minumOSD is a power hog, slurping up about 1.5 amps of that current! I have previously done several calibration cycles for the compass but still get this ultra-low drift, leaving me without a good lead on the cause.
@eber0206,
Are you using a combination GPS/Compass and if so is it a genuine 3DR product or a clone?
Regards,
TCIII GM
It is Ublox Lea-6H-0-002 not from 3DR but from multirotormainia.com. The build quality looks good. I will contact them about this. I apologize if this has been the wrong forum to bring this issue to.
In Mission Planner 1.3.24, over a period of 2 hours and 20 minutes “time in air” the compass “zero” has drifted from 0 degrees to 340 degrees in a clock-wise rotation through each degree, suggesting a DC current or voltage offset in the electronics that has not been nulled or tuned out. I am trying to form a hypothesis for this behavior: thermal offset causing drift seems unlikely as it is steady rate over a long time period. The system is being powered by a 3DR 3 amp BEC with the sensor circuit for voltage and current. The APM 2.8 is driving a 3DR radio and a minumOSD, and a Ublox lea6h-0-002. Current readings in the HUD indicate current nominal consumption at 2.6 to 3.1 AMPs, about maxing out the BEC. By the way, the minumOSD is a power hog, slurping up about 1.5 amps of that current! I have previously done several calibration cycles for the compass but still get this ultra-low drift, leaving me without a good lead on the cause.[/quote]
This problem was created by the user using 2 different sources of 12 volt power, one for the video camera and one to supply the 3DR UBEC. Later, by unifying my supply source to only one (the 12 volt source for the 3DR UBEC) a ground or power “current loop” was discovered and eliminated. The problem current loop was inducing a DC current flow offset into the APM and was expressing itself by dumping through the compass electronics. The current loop was 1 amp! This problem was user caused and not an issue with the electronics. As you may infer, ground or power loops can be quite destructive over time to electronics. I discovered this one in time (not the first one I have ever encountered!)