Hi,

I chrashed with my Mavic a few weeks ago and should therefor recalibrate the compass. I just haven't had the chance yet due to stuff and bad weather (I planned to go calibrate and fly today, but the weather is too bad :-( )

I've used an iPhone 6 iOS 10, but wanted some more screen space so I've bought a tablet Lenovo Tab3 7 runnning Android 5.0.1.
But some inconsistency has arisen.

Why does the iPhone tell me that the compass needs to be calibrated when the tablet says the compass is fine?

/Jost

Did you power on the mavic @ exactly the same place?

Eagle_Eye Posted at 2017-10-21 07:31
Did you power on the mavic @ exactly the same place?

Well, not the exactly same place, but in my living room and each spot not further than 1.5 meters from each other. And I have powered it up several times and iOS always says that the compass has to be calibrated and Android never do.

Jost Posted at 2017-10-21 13:53
Well, not the exactly same place, but in my living room and each spot not further than 1.5 meters from each other. And I have powered it up several times and iOS always says that the compass has to be calibrated and Android never do.

Because there can be interference inside a home, I would check outside in a clear area. There are some difference in the code between IOS and Android and perhaps the IOS is more sensitive to interference.

Agree with 3#. Change to another open place without interference to check again.

This is not good, either the ios go4 is corerct or the android version is, if you fly with ios then all you need to do is recal and all will be well, however if you use android then you may not know the compass needs recalibrating until it's too late, dji really need to seriously look into this if indeed the op is correct.

Jost Posted at 2017-10-21 13:53
Well, not the exactly same place, but in my living room and each spot not further than 1.5 meters from each other. And I have powered it up several times and iOS always says that the compass has to be calibrated and Android never do.

1.5m indoors can make a massive massive difference to the electrical and magnetic environment.

Can you post the screenshot of the Compass readings in both apps, while Mavic is powered up at exactly the same spot?
Settings top tab -> Advanced Settings -> Sensors -> Compass

I sometimes get a compass prompt error due to mag interference,but when I move the MP a foot or 2 from that spot the error most of the times cleared.

Just calibrate outside in a great big field when the app asks.  Wouldn't ever consider doing it inside.

Ok, took a little investigating, but here's my conclusion. The cell phone has a magnetometer/compass. When two devices are i close proximity, the drone and phone, there may be interference. The Lenovo Tab 3.7 does NOT have a compass/ magnetometer. The tab 2 does, but for reasons that are not clear, it was removed on the Lenovo.

For high accuracy location, the magnetometer is needed but is will cause some interference when two such devices are near each other.

Also, review the following:
Safe distances for compass calibration

6” (15 cm) minimum: Metal rim glasses, pen/pencil, metal watch band, pocket knife, metal zipper/buttons, belt buckle, batteries, binoculars, cell phone, keys, camera, camcorder, survey nails, metal tape measure.
18” (50 cm) minimum: Clipboard, data collector, computer, GPS antenna, 2-way radio, hand gun, hatchet, cell phone case with magnetic closure.
6 ft (2 m) minimum: Bicycle, fire hydrant, road signs, sewer cap or drain, steel pole, ATV, guy wire, magnets, chain-link fence, bar-wire fence, data collectors

that use a magnet to hold the stylus.
15 ft (5 m) minimum: Electrical box, small car/truck, powerline, building with concrete & steel.
30 ft (10 m) minimum: Large truck, metal building, heavy machinery.

I went out on a grass field today and calibrated the compass, so I can't do a new screenshot. Well, not until the compass needs calibration again.

But it seems that fansdf099539 found an explanation. Thanks.

fansdf099539 Posted at 2017-10-22 06:25
Ok, took a little investigating, but here's my conclusion. The cell phone has a magnetometer/compass. When two devices are i close proximity, the drone and phone, there may be interference. The Lenovo Tab 3.7 does NOT have a compass/ magnetometer. The tab 2 does, but for reasons that are not clear, it was removed on the Lenovo.

For high accuracy location, the magnetometer is needed but is will cause some interference when two such devices are near each other.

Where did you get these numbers from?  This is good information.

I'll be linking to this post for future reference.

Jost Posted at 2017-10-22 14:34
I went out on a grass field today and calibrated the compass, so I can't do a new screenshot. Well, not until the compass needs calibration again.

But it seems that fansdf099539 found an explanation. Thanks.

Read the whole manual before you fly, these are basics, like this...