IMU Calibration needed?

[pianoflyer]

I connected to Phantom 2 Assistant today to adjust my flight limits and when I clicked the " Check IMU Status " button ( there may have been a " calibrate notice , I don't remember) for the first time I got an " IMU CALIBRATION NEEDED" . I followed instructions , did "basic calibration" and now when I check the IMU status I get " no need calibration can be skipped".... this is okay, right? Why would it need to be calibrated? I did just take off prop guards and add better antenna to video tx and a new gps tracker.. Would those additions cause the need for IMU calibration?
Thanx

 

[Mako79]

I reckon you got a compass warning appear on the phantom assist. This happens when you place the phantom near metal objects or on the ground with rebar.

You should do IMU calibrations only if you have a bump landing or need to fix yaw issues. Just check the mod values regularly.

On a side note, I placed my phantom on my backpack and it fell over (phantom was off with no props). I plugged it into the Assist and the mod values up to 4.1. I redid the Adv calibrations and everything seems normal. This shows how sensitive the IMU Is.

 

[pianoflyer]

after doing basic re-calibration of IMU , on flat surface, the first mod # is drifting between 0.0 and 0.4....I assume that is in the correct range. In other words, it's okay that it is not "Locking in" at 0.00...
Drift is okay, even if it's standing still?
Thanks