Does the Mavic work like P4P

[jase888]

I use to have a P4P last year but had to sell it due to buying a new house....was gutted. But this weekend im at a wedding and said id get an aerial photo for the couple (this was when i still had drone) so decided to hire a Mavic Pro for a few days.as its not much.

My question as i have forgot do you need to calibrate compass every flight for DJI drones? Or is it just when you go to a new area?

Ive watched a few youtube videos and seen some calibrate others not before flight which makes me think you only need to do it once every now and then?

 

[LarBear360]

I use to have a P4P last year but had to sell it due to buying a new house....was gutted. But this weekend im at a wedding and said id get an aerial photo for the couple (this was when i still had drone) so decided to hire a Mavic Pro for a few days.as its not much.

My question as i have forgot do you need to calibrate compass every flight for DJI drones? Or is it just when you go to a new area?

Ive watched a few youtube videos and seen some calibrate others not before flight which makes me think you only need to do it once every now and then?

You're either from the UK or New York! In the US, we "rent" things rather than "hire" them. Except in New York :>

Regardless, the compass calibration is debatable but since you don't know where your Mavic has been, it wouldn't hurt to perform a compass calibration just to be safe.

I won't go into the whole "Part 107" thing because that was not the question, but the last time a similar question was asked (wedding and all), the thread turned into a huge debate about whether or not he was qualified, permitted, licensed, whatever to take a picture of a wedding with his drone.

Just sayin.

 

[John Locke]

My question as i have forgot do you need to calibrate compass every flight for DJI drones

You do not need to calibrate every time. If it has flown recently, you're good to go. However, rented gear should be test flown before the wedding day to insure everything works. Take sample photos and video during the test to insure the card you're using is good, and the capture is recorded and readable with your computer. It sounded like you're doing this as a favor, so if you are not selling the photos, no worries on the commercial Part 107 requirements if you're in the US.

 

[Meta4]

My question as i have forgot do you need to calibrate compass every flight for DJI drones? Or is it just when you go to a new area?

Ive watched a few youtube videos and seen some calibrate others not before flight which makes me think you only need to do it once every now and then?

The Mavic works exactly like the Phantom.
There is a great deal of myth and superstition surrounding compass calibration, what it does and when it's necessary.
There should never be any need to calibrate the compass.
It doesn't matter when you last flew, how far you travelled etc.
If the Mavic hovers in place without slowly spiraling, the compass is fine and calibrating it won't make anything work any better.

I had to look up the Mavic manual and it's interesting to note that DJI haven't updated it.
It still has incorrect and misleading information on compass calibration.
DJI updated this for more recent Phantoms to remove the false suggestions about recalibrating at new sites.

I've never calibrated the compass in my P4 pro bought more than 1.5 yrs ago.
I've flown at sites more than 1000 miles from home and everything works perfectly.
Compass calibration is not needed under normal circumstances.

 

[LarBear360]

The Mavic works exactly like the Phantom.
There is a great deal of myth and superstition surrounding compass calibration, what it does and when it's necessary.
There should never be any need to calibrate the compass.
It doesn't matter when you last flew, how far you travelled etc.
If the Mavic hovers in place without slowly spiraling, the compass is fine and calibrating it won't make anything work any better.

I had to look up the Mavic manual and it's interesting to note that DJI haven't updated it.
It still has incorrect and misleading information on compass calibration.
DJI updated this for more recent Phantoms to remove the false suggestions about recalibrating at new sites.

I've never calibrated the compass in my P4 pro bought more than 1.5 yrs ago.
I've flown at sites more than 1000 miles from home and everything works perfectly.
Compass calibration is not needed under normal circumstances.

I've owned my P3S for about one year and have only calibrated once. And like John suggested, test, test, test everything.

 

[jase888]

Thanks for responses. Ok I'm probably do it once to be safe but not every flight like I thought you had too. I will be testing it today before wedding as been a while since I've flown.

And yeah I'm from the UK haha

 

[tcope]

There should never be any need to calibrate the compass.
It doesn't matter when you last flew, how far you travelled etc.

DJI updated this for more recent Phantoms to remove the false suggestions about recalibrating at new sites.

Compass calibration is not needed under normal circumstances.

The OP is asking about the Mavic, not a Phantom (albeit, in the incorrect form).

Here is what DJI actually recommends for the Mavic:

#1 (the first thing they recommend)... calibrate when flying at a location further than 10km away from the last flight.

 

[sar104]

The OP is asking about the Mavic, not a Phantom (albeit, in the incorrect form).

Here is what DJI actually recommends for the Mavic:

View attachment 100894

#1 (the first thing they recommend)... calibrate when flying at a location further than 10km away from the last flight.

DJI's manuals unfortunately are not always up to the standards of their hardware, and have a long history of randomly including mis-statements. This is one of them. There was never any basis for the "recalibrate if you change location" advice, which is why, presumably, it was removed from other product manuals. In any case, it is pointless advice since the purpose of the calibration is to subtract out the magnetic field of the aircraft, which should not change with location unless it becomes magnetized on the journey. It has nothing to do with the characteristics of the earth's magnetic field - that does vary with location but the aircraft has no way to measure the only important aspect that changes (declination) by the calibration process. It gets the location-dependent declination from a global model in the firmware.

 

[tcope]

There was never any basis for the "recalibrate if you change location" advice, which is why, presumably, it was removed from other product manuals.

So I looked electronic compasses and the like and your post. Here is what I think the deal it. Prior to the P4 (might be P3... but at least up until the P2) there was one IMU in the Phantom. I think with the installation of two IMU's the system is able to self diagnose. I think this is done by comparing readings from the two IMUs. If they are not the same, the software will prompt the user to recalibrate. But, as you mentioned, DJI never removed the old information from the manuals. They eventually removed it from the Phantom manual but not the Mavic manual.

So I would agree with Meta4 and your post, that it does not need to be done unless prompted.

Thanks sar104, thanks Meta4.

 

[Droner66]

I just returned to Arkansas from Texas. I did some flying there while on vacation. Just fired it up at home to make sure everything was ok and I got the calibrate compass message. I have a P3P and using Lichi. Once calibrated it flew fine.

 

[smiller]

And forcing a calibration in an area with magnetic anomalies could potentially do more harm than good. The compass is self-calibrating and does not need any user intervention. Except for special circumstances (the unit is indicating a fault or asking for a calibration) the simple rule is that routine manual calibration is neither necessary nor desirable. The unit will let you know if it's unhappy.

 

[sar104]

So I looked electronic compasses and the like and your post. Here is what I think the deal it. Prior to the P4 (might be P3... but at least up until the P2) there was one IMU in the Phantom. I think with the installation of two IMU's the system is able to self diagnose. I think this is done by comparing readings from the two IMUs. If they are not the same, the software will prompt the user to recalibrate. But, as you mentioned, DJI never removed the old information from the manuals. They eventually removed it from the Phantom manual but not the Mavic manual.

So I would agree with Meta4 and your post, that it does not need to be done unless prompted.

Thanks sar104, thanks Meta4.

In terms of calibrating the compass, the number of IMUs (or even compasses) is not the issue.

The compasses (3-axis magnetometers to be precise) simply measure the 3-D magnetic field. The single piece of data that the FC needs from the compass(es) is the direction of magnetic north relative to the aircraft, derived from the horizontal component of the earth's field that is aligned magnetic north-south. However, due to its ferromagnetic components, the aircraft has its own magnetic field, so that the field measured by the magnetometers is actually a linear sum of the two. The FC needs to know the aircraft's magnetic field so that it can subtract that from the measured magnetic field, leaving just the earth's magnetic field. It learns the aircraft's magnetic field by the calibration process, since that field is the one that doesn't change when the aircraft is rotated, unlike the earth's field that obviously appears to spin as the aircraft turns. That is all that calibration is for.

The longstanding misconception that calibration is to correct for magnetic declination is obviously incorrect. Magnetic declination is the location-dependent difference between magnetic north (that the magnetometer measurements provide once the aircraft's field has been subtracted) and true north. A compass, no matter how you rotate it, can never determine declination because true north is, magnetically, an arbitrary direction, and neither the compass nor any of the other sensors can determine the direction of true north without prior knowledge of the local declination. The local declination is actually provided by a global model of the earth's magnetic field that is loaded into the firmware.

The addition of multiple compasses is to compare their values, and might be useful to determine if one or both is out of calibration, but it does not change the conditions that require calibration, which are a change in the magnetic state of the aircraft.

Just for comparison, the P4 series has two IMUs and two compasses, the Mavic Pro has one IMU and two compasses, and the Mavic Air has two IMUs and one compass. The same calibration advice applies to all of them.

 

[Meta4]

I just returned to Arkansas from Texas. I did some flying there while on vacation. Just fired it up at home to make sure everything was ok and I got the calibrate compass message. I have a P3P and using Lichi. Once calibrated it flew fine.

The message you got was not related to the distance travelled.
It was almost certainly related to the distance between your Phantom's compass and some magnetic material.
If you had just moved away from the magnetic influence, the warning would have gone.
Moving any distance across the earth makes no difference to the Phantom's compass and calibration should never be required unless you modify the Phantom.

I'm 1500 miles from home and my Phantom flies just as well as it does back home.
Still haven't calibrated anything since I bought it 1.5 years ago.

 

[smiller]

The message you got was not related to the distance travelled.
It was almost certainly related to the distance between your Phantom's compass and some magnetic material.
If you had just moved away from the magnetic influence, the warning would have gone.

Yes, and in fact in some cases the operator should exercise judgment even if the aircraft asks to be calibrated. One area I fly at is a large concrete parking lot with a lot of rebar and the resulting magnetic disturbance often triggers the unit to ask for a compass calibration, but that would actually be a terrible place to do so.

 

[Meta4]

Yes, and in fact in some cases the operator should exercise judgment even if the aircraft asks to be calibrated. One area I fly at is a large concrete parking lot with a lot of rebar and the resulting magnetic disturbance often triggers the unit to ask for a compass calibration, but that would actually be a terrible place to do so.

The message reads: Move aircraft or Calibrate compass.
Very few people notice the first part of the message and the second part is incorrect.
Calibrating will never "fix" the magnetic influence that the compass is warning about.

 

[Matchlock]

I can not remember the last time I calibrated the compass on any of my DJI quads, and I flew all last year, and so far this year without any additional calibration other than the original one.

To be clear, I normally fly within about a 160 or so sq. mile area, (40mile X 40mile) and when I go to my brother's place which is about 75 miles the south west, I don't calibrate it there either.

Bud

I use to have a P4P last year but had to sell it due to buying a new house....was gutted. But this weekend im at a wedding and said id get an aerial photo for the couple (this was when i still had drone) so decided to hire a Mavic Pro for a few days.as its not much.

My question as i have forgot do you need to calibrate compass every flight for DJI drones? Or is it just when you go to a new area?

Ive watched a few youtube videos and seen some calibrate others not before flight which makes me think you only need to do it once every now and then?

 

[David_Cambridge]

One of the issues not mentioned in the multitude of compas calibration is how the drones determine magnetic variation which is the difference between true north and magnetic north, which does change from location to location. Does the DJI machine calculate it from it’s GPS position? Does it even need to take this into account for the flight control system to work properly?

 

[sar104]

One of the issues not mentioned in the multitude of compas calibration is how the drones determine magnetic variation which is the difference between true north and magnetic north, which does change from location to location. Does the DJI machine calculate it from it’s GPS position? Does it even need to take this into account for the flight control system to work properly?

As I mentioned in post #12 above it determines that from its location (from GPS) and a global declination model. It does need that in order to fly because its positional frame of reference is lat/long, which is oriented relative to true north, not magnetic north.