Dear All,

I have a customer that has purchased a DJI Phantom 2 Vision+ V3 from us recently. The customer is reporting an inaccurate altitude reading of + 6 Meters (19.6Ft) at ground level or take off. Sometimes the unit will read a 0 Meter level at take off but further into the flight will read at a positive reading when on the ground.

Advanced calibrations have been preformed on the unit. The unit also has a 7+ satellites locked in with a green flash pattern (good for take off).
From what I can tell the unit has a barometric altimeter however there is no way to enter pressure therefore temperature can have a big effect on the readout. The Return to home descends at a constant rate so an inaccurate reading for altitude should not hinder or damage the unit if it's on a RTH.

Does anyone have any experience with the barometric altimeter in the phantom 2 series that may know of a fix or solution to calibrate or reset the readout?


Thankyou,


Zack

That sounds about right; there is no way to set a 0 and it changes with weather so you can expect it to be off.

RTH will be fine; the descent rate does not land the craft too fast and it will land without damage, at least that is what I have found in all the times I use RTH no matter what the initial altitude.  I don't think that the altitude is actually used to calculate ground level; it might be used as a relative location (e.g., if at take off your reading is +20' then landing could know that +20' is the ground) but I've never read such detail so cannot comment on what the firmware might do.

In any case,  summing it up: RTH will be find.

Hi Kenargo,

Thanks for your reply. The major concern with the customer was that the unit is set to RTH altitude of 20 Meters. The unit once required to RTH and flew to what it thought was 20 Meters above the ground and was more close to 10 meters above the ground. The customer had to take control of the Phantom to prevent it from flying into tree's. The customer has since set the RTH altitude at 40 Meters however he also relies on the unit for photography at certain altitudes. There have been forum posts else where that I've seen people sending the units back for a replacement under warranty. On return the barometric reading is again accurate. Something must have to be calibrated or replaced.

Just wondering what that might be, Unfortunately repairs usually take 4-6 weeks here in AUS. Trying to avoid that if possible for our customer.

Cheers,

Zack

Jagaus Posted at 2015-2-4 09:49
Hi Kenargo,

Thanks for your reply. The major concern with the customer was that the unit is set to  ...

Yes, you do need to take the reading into account when setting RTH altitude.  If the ground reads as 20m then you should add that to your RTH altitude or fly higher.  RTH flies at the RTH configured altitude or the altitude you are flying, whichever is higher.  The craft will NOT come lower to RTH, it only moves higher (if you are currently below the configured altitude).

I have not heard of any calibration routine (public or otherwise) so I can't comment if a repair would help but I suspect not.

Jagaus Posted at 2015-2-4 09:49
Hi Kenargo,

Thanks for your reply. The major concern with the customer was that the unit is set to  ...

There is no known calibration and repair usually involves replacement of the Naza-M V2 controller

Thanks for the replies