Compass Calibration, A Complete Primer

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#42
Why Calibrate?
Compass calibration is important to safe, controlled flight. It compensates for changing background magnetic "noise", a.k.a. magnetic inclination and deviation (not to be confused with declination). Inclination and deviation that isn't corrected through compass calibration will cause inconsistencies between GPS and compass that can result in "toilet bowl effect", a swirling motion that can cause the Phantom to fly out of control.

What is Magnetic Inclination and Deviation?
Magnetic deviation is a horizontal variation that comes from the Phantom itself and the equipment you have installed on it as well as the magnetic makeup of the area you are flying in (again not to be confused with declination). Sometimes the deviation will be insignificant, but other times it can be big enough to cause you to lose control. Inclination is a vertical magnetic variation that shifts depending on where you are.

Warning Signs
The Phantom can only detect when the compass is providing extremely poor (implausible) data. This typically occurs if you place it near a strong magnetic field or do not calibrate it properly. It will flash red and yellow lights and the P3 will indicate a compass error in the app.

IMPORTANT: The lack of a compass error does NOT mean your compass is working and calibrated properly.

MOD Value
This is the total magnetic field calculated using the "sum of squares" from the X, Y and Z axes. On the P2, you need to plug in the cable and use the assistant software. For the P3, you can see it in the app. It should be between 1,200 and 1,500, ideally just above 1,400. Check it away from magnetic influences. If it reads very high or very low, check it again in a different location. If it is still off, it could need calibration or it could be magnetized or damaged.

IMPORTANT: A good mod value does NOT mean your compass is working and calibrated properly. For example, if you calibrate next to some rebar, your mod value may still be OK until you fly away from the rebar.

What Does Calibration Actually Do?
Calibration measures the magnetic fingerprint of the surrounding area. By turning the compass 360 degrees, the Phantom can see where the compass reading doesn't smoothly increase or decrease. It uses this information to build an adaption table so that when the Phantom turns during flight, the reading is smooth and linear.

When Should I Calibrate?
You do not need to calibrate before every flight and in some cases you definitely should not calibrate. That doesn't mean you shouldn't ever bother doing it. It only takes one time for it to go very wrong. The most important aspect of compass calibration is making sure the magnetic "neighborhood" around your Phantom is consistent between calibration and during flight.

IMPORTANT: The ideal place to calibrate is an open field with nothing in a 20ft radius. Keep away from drainage pipes, irrigation systems, rocks, etc.
  • DO Calibrate
    • Mod value out of whack or compass error reported (check area first).
    • Circling in flight (also check for other possible causes).
    • New equipment added or removed / new firmware installed.
    • Location change (greater than ~100 miles).
    • Significant change in terrain (e.g. to / from mountains).
    • If you just degaussed your compass (BTW, don't degauss unless instructed).
  • DO NOT Calibrate
    • If near concrete, buildings, and hidden or overhead power lines / pipes / etc.
    • If you're indoors, on a paved surface, on a stone surface, on the beach, on a boat, on a balcony, near a car, near speakers, etc.
    • If there are metallic (ferrous) objects nearby or you're not sure
  • Pre-Calibration Checklist
    • Everything used in flight should be powered during calibration, e.g. GoPro, tracker, etc.
    • Remove all metal from within 10ft radius, e.g. watch, phone, ring, belt, coins, controller.
    • Calibrate on grass or dirt and not on concrete, asphalt.
    • Calibrate on a level surface if possible.
    • A cardboard box is a good idea to get it off the ground and level.
  • How to Calibrate
    • Power up your Phantom and accessories as normal.
    • Wait until your Phantom is ready to fly.
    • P1 / P2: Flip S1 five times between the top two positions.
      P3: Select CALIBRATE under AIRCRAFT STATUS | COMPASS. Click OK.
    • Confirm solid yellow rear lights.
    • Pick up the Phantom and turn it smoothly and steadily a full 360 degrees until the lights turn solid green.
    • Point the front of the Phantom straight down and repeat until the lights turn off and resume normal flashing.
      Note: Don't be concerned if your gimbal reacts poorly to being face down, keep turning as normal.
    • Optional: power off and restart Phantom.
    • Enjoy your flight!
If for any reason, you do not complete any of the above steps smoothly and evenly, restart the process.
@ianwood
Hello Ian! I have a P2V that I added a Rotor Pixel gimbal to and have a really hard time calibrating the compass as the gimbal tends to quiver a bit in the nose down part of the compass dance. After a dozen tries I end up powering down the P2V unplug the gimbal do the dance and I have no problems calibrating the compass. I power down plug back in the gimbal and power up again and then fly. I have never had any problems with control of the P2V but after reading your post it has me wondering if I am setting myself up for a potential problem:eek:. Thanks in advance for your response;)
 
Joined
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#43
I see this is an old thread but it's the closest I can find to my problem.
After many compass calibrations I still get a "?" showing on my App page.
So apparently my calibration is not working. Evidenced by erratic flying and crashing.
I'n a nube so I must be doing something wrong.
 
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#44
Which Phantom, what version of firmware, what app, what version?

More importantly, what are your LEDs doing when placed in calibration mode, what do they do after your first revolution and after pointing down and rotating what do the LEDs do?
 
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#45
Which Phantom, what version of firmware, what app, what version?

More importantly, what are your LEDs doing when placed in calibration mode, what do they do after your first revolution and after pointing down and rotating what do the LEDs do?
Thanks for the reply,

P3A
1.4.10 firmware
remote 1.4.30
DJI GO 2.4.0 App for Andriod Tab 4

After pressing "Calibrate"
steady yellow
rotate
steady green
rotate single blinking green

Pressing yellow dot with "?" opens a message to calibrate
 

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Joined
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#46
Why Calibrate?
Compass calibration is important to safe, controlled flight. It compensates for changing background magnetic "noise", a.k.a. magnetic inclination and deviation (not to be confused with declination). Inclination and deviation that isn't corrected through compass calibration will cause inconsistencies between GPS and compass that can result in "toilet bowl effect", a swirling motion that can cause the Phantom to fly out of control.

What is Magnetic Inclination and Deviation?
Magnetic deviation is a horizontal variation that comes from the Phantom itself and the equipment you have installed on it as well as the magnetic makeup of the area you are flying in (again not to be confused with declination). Sometimes the deviation will be insignificant, but other times it can be big enough to cause you to lose control. Inclination is a vertical magnetic variation that shifts depending on where you are.

Warning Signs
The Phantom can only detect when the compass is providing extremely poor (implausible) data. This typically occurs if you place it near a strong magnetic field or do not calibrate it properly. It will flash red and yellow lights and the P3 will indicate a compass error in the app.

IMPORTANT: The lack of a compass error does NOT mean your compass is working and calibrated properly.

MOD Value
This is the total magnetic field calculated using the "sum of squares" from the X, Y and Z axes. On the P2, you need to plug in the cable and use the assistant software. For the P3, you can see it in the app. It should be between 1,200 and 1,500, ideally just above 1,400. Check it away from magnetic influences. If it reads very high or very low, check it again in a different location. If it is still off, it could need calibration or it could be magnetized or damaged.

IMPORTANT: A good mod value does NOT mean your compass is working and calibrated properly. For example, if you calibrate next to some rebar, your mod value may still be OK until you fly away from the rebar.

What Does Calibration Actually Do?
Calibration measures the magnetic fingerprint of the surrounding area. By turning the compass 360 degrees, the Phantom can see where the compass reading doesn't smoothly increase or decrease. It uses this information to build an adaption table so that when the Phantom turns during flight, the reading is smooth and linear.

When Should I Calibrate?
You do not need to calibrate before every flight and in some cases you definitely should not calibrate. That doesn't mean you shouldn't ever bother doing it. It only takes one time for it to go very wrong. The most important aspect of compass calibration is making sure the magnetic "neighborhood" around your Phantom is consistent between calibration and during flight.

IMPORTANT: The ideal place to calibrate is an open field with nothing metallic in a 20ft radius. Keep away from drainage pipes, irrigation systems, rocks, etc.
  • DO Calibrate
    • Mod value out of whack or compass error reported (check area first).
    • Circling in flight (also check for other possible causes).
    • New equipment added or removed / new firmware installed.
    • Location change (greater than ~100 miles).
    • Significant change in terrain (e.g. to / from mountains).
    • If you just degaussed your compass (BTW, don't degauss unless instructed).
  • DO NOT Calibrate
    • If near concrete, buildings, and hidden or overhead power lines / pipes / etc.
    • If you're indoors, on a paved surface, on a stone surface, on the beach, on a boat, on a balcony, near a car, near speakers, etc.
    • If there are metallic (ferrous) objects nearby or you've


    • a e
    • Pre-Calibration Checklist
      • Everything ussed in flight should be powered during calibration, e.g. GoPro, tracker, etc.
      • Remove all metal from within 10ft radius, e.g. watch, phone, ring, belt, coins, controller.
        [
        *]Calibrate on grass or dirt and not on concrete, asphalt.
      • Calibrate on a level surface if possible.
      • A cardbxoard box is a good idea to get it off the ground and level.
    • How to Calibrate
      • Power up your Phantom and accessories as normeal.a s
      • Wait until your Phantom is ready to fly.
      • P1 / P2: Flip S1 five times between the top two positions.
        P3: Select CALIBRATE under AIRCRAFT STATUS | COMPASS. Click OK.
      • Confirm solid yellow rear lights.
      • Pick up the Phantom and turn it smoothly and steadily a full 360 degrees until the lights turn solid green.
      • Point the front of the Phantom straight down and repeat until the lights turn off and resume normal flashing.
        Note: Don't be concerned if your gimbal reacts poorly to being face down, keep turning as normal.
      • Optional: power off and restart Phantom.
      • Enjoy your flight!
    If for any reason, you do not complete any of the above steps smoothly and evenly, restart the process.

  • I :-! Sees
 
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#47
Thanks for the input. I have actually done all of it about three times. I'll try it again though, maybe I missed something. I still show that "?" in the yellow circle. It never goes away. Does that in fact indicate a compass problem?
Any info on degausing?
 
Last edited:
Joined
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#48
Thanks for the input. I have actually done all of it about three times. I'll try it again though, maybe I missed something. I still show that "?" in the yellow circle. It never goes away. Does that in fact indicate a compass problem?
Any info on degausing?
 
Joined
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#49
I'm not familiar with android messages, but if the screen says "Normal" and your LEDs blink the correct sequences. I would think you are good to go.

The concern would be where are your trying to calibrate your compass? Over some concrete with a mass of rebar embedded, over some buried electrical lines, or near some other metal structure. If you haven't already, find a nice open grassy area with little to no chance of metal structures causing your compass failure.
 
Joined
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#50
ianwood, rare is the beach that has iron in it, and certainly not enough to cause compass calibration problems for a Phantom. I'm not thrilled about flying from a dry sandy beach, however, just because of the way sand can get into everything as you mentioned. I've flown many times from a wet sandy beach.
It's not rare at all and is actually quite common. Black sand as it is called, is just below the surface of the sand. I've been gold mining as a hobbyist for 35+ years. Been to beaches up and down the West and East coast.. even the Gulf. Every beach had black sand in it. Some in greater concentrates then others. In the early years, detectors would scream on beaches. With advances in technology, we can "notch out" the iron signals.

Now the question becomes... is passive technology effected by iron on the beach? Since you are calibrating above the ground by a few feet, I would think not.... But, I wouldn't chance it with my $1300.00 quad.
 
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ianwood

Taco Wrangler
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#51
Thanks for the input. I have actually done all of it about three times. I'll try it again though, maybe I missed something. I still show that "?" in the yellow circle. It never goes away. Does that in fact indicate a compass problem?
Any info on degausing?
That's possible but it is uncommon. I would want to confirm that no metal is anywhere near your calibration area first. Put the bird on some cardboard, then nothing else man made for 15ft in all directions including up and down and on your person. If you have metal anywhere from surgery, get someone else to turn it.

Make sure when you calibrate, the motion is smooth and even and the orientation of the bird is consistent in the non-spinning axes.
 
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#52
I have tried the middle of an empty 1000 acre tomato crop field in the middle of the San Joaquin Valley, CA with no overhead phone or power lines in site.

But

I never considered trying my iphone instead of the Andriod. Now the yellow dot is gone, did a test flight for 10 minutes and no problems so far YEAH!
Thank you Buk!
 
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#53
Ianwood, thanks for the great info... it is nice to hear from an expert. Do the "Image Transmission Settings" have any impact or relationship on the compass. I know this may sound stupid, but yesterday I had a major compass error after a perfect compass calibration 150 miles form the last calibration. The one thing I did not do was change my custom "Image Transmission Setting" and after landing I checked it and it was way out of whack... set on a channel with lots of interference. Have not have a chance to fly since.
 

Meta4

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#55
Ianwood, thanks for the great info... it is nice to hear from an expert. Do the "Image Transmission Settings" have any impact or relationship on the compass. I know this may sound stupid, but yesterday I had a major compass error after a perfect compass calibration 150 miles form the last calibration.
Almost certainly this would have no impact at all on compass.
I can't tell from here with no knowledge about where you calibrated but I'd guess the most likely explanation is that your perfect calibration was in an imperfect location.
It's most important that there's no iron or steel in the vicinity, including buried pipes or reinforcing steel.
 

Meta4

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#56
Why can't calibrate on asphalt?
You can .. as long as it isn't a layer of asphalt on concrete like maybe a parking structure etc or asphalt with buried pipes, cables etc.
Most asphalt roadways, parking lots etc will not have these potential issues but always be on the lookout
 
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#58
Smartphones have sensitive flux sensors and most compass apps will reveal fields strong enough to cause problems. Tiny speakers often have neodymium magnets in them and these will definitely cause issues, etc. If the compass on your phone shows interference or goes haywire your phantom probably will too!

Just remember to keep the phone away while doing the calibration! ;)
 
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#59
Every time I do the startup on all the pieces, and hit the camera selection on the iPad screen the app opens up and the calibrate selector opens up and asks the Yes/No question. Does that not mean that the drone compass needs to be calibrate, or are you saying that I should say no unless I am far from the last flight??
 

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