Calibrate compass in a saline

[ArgenBrewer]

I need to ask a question to the most experienced; I will soon have the opportunity to travel to a large expanse of salt mines in my country and it occurred to me that it could be the ideal place to calibrate the compass in an environment absolutely free of electromagnetic interference, buildings, power lines, cement, elevations, rocks, etc. but I have doubts about the salt that forms the soil of the place, will it have any influence on the Phantom's sensors?
Thank you for your attention!

 

[Meta4]

I need to ask a question to the most experienced; I will soon have the opportunity to travel to a large expanse of salt mines in my country and it occurred to me that it could be the ideal place to calibrate the compass in an environment absolutely free of electromagnetic interference, buildings, power lines, cement, elevations, rocks, etc. but I have doubts about the salt that forms the soil of the place, will it have any influence on the Phantom's sensors?

Under normal circumstances, there should be no need to calibrate your Phantom's compass.
If it flies straight and hovers in place without slowly rotating, everything is fine and there's nothing to gain by recalibrating the compass.

The salt would have no effect on the compass or other sensors.

 

[ArgenBrewer]

Thank Meta4 ,Actually I do not have compass problems and normally I do not make new calibrations since the last one I did in the middle of a field but if I had some Wi-Fi signals nearby. my intention was to make a new one in a "cleaner place even" and leave that for the future.

 

[sar104]

Thank Meta4 ,Actually I do not have compass problems and normally I do not make new calibrations since the last one I did in the middle of a field but if I had some Wi-Fi signals nearby. my intention was to make a new one in a "cleaner place even" and leave that for the future.

Wi-fi and other radio-frequency signals will not have any effect on a compass calibration. Local non-uniform magnetic distortions, especially anything magnetic that you might be wearing, are the only factors that will cause problems.

 

[ArgenBrewer]

That is real, sar104, and I should not have mentioned the Wi-Fi at this point, but in fact I was thinking that the presence of Wi-Fi also indicates the presence of power lines and constructions that, if they affect the compass, are you in agreement with that?

 

[sar104]

That is real, sar104, and I should not have mentioned the Wi-Fi at this point, but in fact I was thinking that the presence of Wi-Fi also indicates the presence of power lines and constructions that, if they affect the compass, are you in agreement with that?

You would need to be pretty close to ferromagnetic structures in order for it to matter. Even a detectable but uniform external magnetic field doesn't matter unless it is strong, because the purpose of the calibration is to identify the magnetic field of the aircraft itself.

 

[N017RW]

Calibrarion does not cancel or compensate for external magnetic distortions. ONLY those created by ferrous metals WITHIN the aircraft. This is why you spin or rotate the aircraft to perform the compensation.

If you have a proper flying aircraft and no warnings in the app leave it alone.

 

[LuvMyTJ]

My personal method is to calibrate the compass if I travel 100 miles from where I last calibrated it.
Depending on where you live the magnetic declination can affect it.

 

[sar104]

My personal method is to calibrate the compass if I travel 100 miles from where I last calibrated it.
Depending on where you live the magnetic declination can affect it.

View attachment 96063 View attachment 96064

Actually magnetic declination plays no part in the compass calibration - the FC determines the declination from a global model based on its location. All that the calibration is attempting to do is measure the aircraft's magnetic field so that it can subtract that from the total magnetic field measured by the magnetometers during operation, leaving, in theory, just the earth's magnetic field which is what it needs for flight control.

 

[LuvMyTJ]

Actually magnetic declination plays no part in the compass calibration - the FC determines the declination from a global model based on its location. All that the calibration is attempting to do is measure the aircraft's magnetic field so that it can subtract that from the total magnetic field measured by the magnetometers during operation, leaving, in theory, just the earth's magnetic field which is what it needs for flight control.

Interesting. I was always under the impression that MD would be a factor.
Does this include all DJI aircraft i.e. older models?

 

[sar104]

Interesting. I was always under the impression that MD would be a factor.
Does this include all DJI aircraft i.e. older models?

That's a fine question. When the P2 was flying j-hook patterns we spent a lot of time trying to figure out whether declination was the problem. The bottom line, however, is that there is no way that rotating the aircraft through the earth's magnetic field could ever allow it to determine declination. Declination, obviously, is the offset of the horizontal component of the earth's magnetic field from true north. The magnetometers can determine the direction of magnetic north (provided there is no magnetic distortion) but, without knowing the direction of true north which the FC has no way to identify, it has nothing to measure against.

 

[LuvMyTJ]

That's a fine question. When the P2 was flying j-hook patterns we spent a lot of time trying to figure out whether declination was the problem. The bottom line, however, is that there is no way that rotating the aircraft through the earth's magnetic field could ever allow it to determine declination. Declination, obviously, is the offset of the horizontal component of the earth's magnetic field from true north. The magnetometers can determine the direction of magnetic north (provided there is no magnetic distortion) but, without knowing the direction of true north which the FC has no way to identify, it has nothing to measure against.

So does that mean the P2 & FC could benefit from the 100 mile method I use? I still have some older quads.

 

[N017RW]

IIRC, it was corrected with the P2 by a firmware update. Prior to that folks were physically offsetting the compass to compensate. This was the Drunken Sparrow project.

Before that the compass and GPS was located externally on a stalk and you were instructed to rotate the stalk to achieve an acceptable adjustment for declination.

 

[ArgenBrewer]

My personal method is to calibrate the compass if I travel 100 miles from where I last calibrated it.
Depending on where you live the magnetic declination can affect it.

View attachment 96063

Well, I will travel more than 950 miles to the north, so on that side I should do it ..

 

[N017RW]

Wait to see.
The farthest I have travelled is 600-700 miles and no need for re-cal.

 

[Meta4]

Well, I will travel more than 950 miles to the north, so on that side I should do it ..

Under normal circumstances, there should be no need to calibrate your Phantom's compass - ever.

 

[ArgenBrewer]

[QUOTE = "N017RW, publicación: 1338543, miembro: 10642"] Espere a ver.
Lo más lejos que he viajado es de 600 a 700 millas y no es necesario volver a llamar. [/ QUOTE]
If I get more paranoid, I would have to see if the limit of 100 miles is equivalent in the southern hemisphere, but I'm not so crazy, hehe

 

[Aussie markD1969]

That was a very interesting read , just 1 question isn’t it good practice to recal compass when u move spots ? . It won’t hurt and only takes a few seconds.

 

[sar104]

Wait to see.
The farthest I have travelled is 600-700 miles and no need for re-cal.

And just in case the theory is not convincing enough, I've taken a Mavic over 5,000 miles, from a region of + 13° to - 5°declination, and seen no adverse effects or any calibration needed messages.

 

[sar104]

So does that mean the P2 & FC could benefit from the 100 mile method I use? I still have some older quads.

I don't think so. As I said, the calibration method is simply unable to make any estimate of declination. It's only needed if the magnetic field of the aircraft changes - if components are changed or added, parts become magnetized etc..

The problem with the P2 appeared to me to be a problem with the use of the declination in the firmware - it looked as if there was a sign error somewhere in the code, leading to a declination error of approximately twice the actual local declination. That was never confirmed - just indicated by experiments. Calibration had no effect on the problem.