Compass Calibration Guide

[networth]

If the compass simply tells NORMAL, that means calibration is not required, right ?

 

[Logger]

Right

 

[MrMavic]

 

[HFMan]

What's interesting about the above- I was in Salt Lake City (some 600 miles west of me) this weekend and did not bother to calibrate the compass. Everything was fine in two days of flying. RTH, intelligent flight modes, orientation, etc were just as good as they were before the trip.

 

[MrMavic]

That's good too know. When I had my phantom 2 and 3, everyone including DJI insisted we had to r-calibrate the compass by doing the drone dance thing before every flight. I for one, thought that was ridiculous.

 

[StuLBNY]

I remember those days. Seems like forever ago.

 

[looopson]

How important is it to calibrate compass after firmware upgrade or downgrade? The DJI Go app never asks you to do that but this tutorial states otherwise...?

 

[jerryflah]

What's interesting about the above- I was in Salt Lake City (some 600 miles west of me) this weekend and did not bother to calibrate the compass. Everything was fine in two days of flying. RTH, intelligent flight modes, orientation, etc were just as good as they were before the trip.

Significant Latitude changes offer more reasons to recalibrate than are Longitude I believe.

 

[BudWalker]

.......
What Does Calibration Actually Do?
Calibration measures the magnetic fingerprint of the surrounding area. By turning the compass 360 degrees, the Mavic 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 Mavic turns during flight, the reading is smooth and linear.
....

When I read this I thought it wasn't copied correctly from
Compass Calibration, A Complete Primer
But, it is copied correctly. However, the process described builds adaptation table for on board magnetic distortions, not, as stated, for the external surrounding area.

To simplify the discussion assume that there are no on board distortions and that any field strength variations on the circumference of the compass dance are caused by external distortions. These field strength variations can't be used to determine the geomagnetic field structure beyond the calibration circumference. A calibration based on these variations would be valid only for flight within the calibration circumference.

To see this consider a simplified example where two calibrations are done next to each other. Further, there is an interference causing field strength variations. Flight with calibration 1 would expect to see maximum field strength in the northeast quadrant whereas using calibration 2 will have the maximum field strength in the northwest quadrant.


Someone may claim that the above example was cleverly constructed so that the two calibrations are different. That by moving the calibrations away from the interference the field will be the same for each calibration. That's true, but, then there won't be any field strength variations on either of the calibrations. Likewise for reducing the intensity of the interference. The key point here is that if the field is distorted enough that the strength varies within the calibration circumference then a different calibration done at a different location will give different results.

 

[Rhcreeps]

Can it be calibrated with the legs folded?.

Why Calibrate?
Compass calibration is important to safe, controlled flight. It compensates for changing background magnetic "noise", a.k.a. magnetic inclination and deviation. 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 Mavic to fly out of control.

What is Magnetic Inclination and Deviation?
Magnetic deviation is a horizontal variation that comes from the Mavic 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 Mavic 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 Mavic 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.

Compass Interference
You can view the current compass interference in the "Main Controller Settings" --> "Advanced Settings" --> "Sensors" section of DJI GO. The colored bars should be in the green (Excellent) range when the Mavic is in a location that is away from magnetic influences. If the bars are in the red (Poor) range or close to it, move the Mavic to a different location and check again. If the compass interference is still in the red (Poor) range or close to it, the compass could need calibrated or it could be magnetized/damaged.

IMPORTANT: A good compass interference value does NOT mean your compass is working and calibrated properly. For example, if you calibrate next to some rebar, the compass interference might report good values 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 Mavic 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 Mavic 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 Mavic is consistent between calibration and during flight.

IMPORTANT: The ideal place to calibrate is an open field with nothing metallic in a 20 ft radius. Keep away from drainage pipes, irrigation systems, rocks, etc.

• DO Calibrate
  • Compass interference values are out of whack or compass error is reported (check area first).
  • Circling in flight (also check for other possible causes).
  • New equipment added or removed.
  • 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 magnetic metallic objects nearby or you're not sure

• Pre-Calibration Checklist
  • Everything used in flight should be powered during calibration (e.g. GPS tracker).
  • Remove all metal from within 10 ft radius (e.g. watch, phone, ring, belt, coins, controller).
  • Calibrate on grass or dirt and not on concrete/asphalt (unless you know the concrete/asphalt does not contain rebar).
  • Calibrate on a level surface if possible.

• How to Calibrate
  • Power up your Mavic and accessories as normal.
  • Wait until your Mavic is ready to fly.
  • Select CALIBRATE under AIRCRAFT STATUS | COMPASS. Click OK.
  • Confirm solid yellow rear lights.
  • Pick up the Mavic and turn it smoothly and steadily a full 360 degrees until the lights turn solid green.
  • Point the front of the Mavic 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.

If for any reason you do not complete any of the above steps smoothly and evenly, restart the process.

─────────────────────────────────────────────────────────
Note: A lot of this information was copied over from ianwood's thread in the Phantom Pilots forum.

 

[BudWalker]

Can it be calibrated with the legs folded?.

No, the calibration needs to be done in the flight configuration; i.e. legs unfolded.

 

[Rhcreeps]

No, the calibration needs to be done in the flight configuration; i.e. legs unfolded.

This question hits me when I remembered that I didn't unfold the legs and it's gave me a strong magnetic interference warning.

 

[BudWalker]

This question hits me when I remembered that I didn't unfold the legs and it's gave me a strong magnetic interference warning.

That's kinda interesting. Did the strong magnetic interference warning come while trying to calibrate? Or, after the legs were unfolded and getting ready to fly?

 

[Rhcreeps]

the whole situation took place when I tried to calibrate it with the leg unfolded. I didn't fly my mavic as i cant calibrate the compass. I tried a few places as i were thinking that it happened because of the place that im standing maybe have a strong interference but the same problem happened at other place as well. I would like to confirm on this, maybe I should try again at the place that I usually fly and calibrate my compass there with the legs folded.

 

[BudWalker]

the whole situation took place when I tried to calibrate it with the leg unfolded. I didn't fly my mavic as i cant calibrate the compass. I tried a few places as i were thinking that it happened because of the place that im standing maybe have a strong interference but the same problem happened at other place as well. I would like to confirm on this, maybe I should try again at the place that I usually fly and calibrate my compass there with the legs folded.

The calibration must be performed with the legs unfolded.

I'm confused since your description has changed. I now understand that you've not been able calibrate because you're getting interference warnings. Does this happen in every location that you've tried? If so, then there is probably something wrong with your Mavic. If not, then once you've obtained a calibration without warnings there is no reason to calibrate again.

A calibration will be rejected (i.e., fail) if there is a magnetic anomaly close enough to the calibration site to be geomagnetically distorted. For example, next to a car, inside a building, etc. Please describe the locations where calibration attempts have been rejected because of strong interference.

 

[EASTA]

Is it common for you guys having compass issues trying to fly inside of cities? Every time I tried it I got a magnetic field alarm.

 

[Inspirephil]

Why Calibrate?
A good compass calibration is important to ensure a safe, controlled flight.

Warning Signs
The Mavic can only detect when the compass is providing extremely poor (implausible) data. This typically occurs if you place it near a strong magnetic field. It will flash red and yellow lights and the Mavic 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.

Compass Interference
You can view the current compass interference in the "Main Controller Settings" --> "Advanced Settings" --> "Sensors" section of DJI GO. The colored bars should be in the green (Excellent) range when the Mavic is in a location that is away from magnetic influences. If the bars are in the red (Poor) range or close to it, move the Mavic to a different location and check again. If the compass interference is still in the red (Poor) range or close to it, the compass could need calibrated or it could be magnetized/damaged.

IMPORTANT: A good compass interference value does NOT mean your compass is working and calibrated properly.

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.

IMPORTANT: The ideal place to calibrate is an open field with nothing metallic in a 20 ft radius. Keep away from drainage pipes, irrigation systems, rocks, etc.

• DO Calibrate
  • Compass interference values are out of whack or compass error is reported (check area first).
  • Circling in flight (also check for other possible causes).
  • New equipment added or removed.
  • 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 magnetic metallic objects nearby or you're not sure

• Pre-Calibration Checklist
  • Everything used in flight should be powered during calibration (e.g. GPS tracker).
  • Remove all metal from your person that could potentially be held near the Mavic while you're calibrating (e.g. watch or rings).
  • Calibrate on grass or dirt and not on concrete/asphalt (unless you know the concrete/asphalt does not contain rebar).

• How to Calibrate
  • Power up your Mavic and accessories as normal.
  • Wait until your Mavic is ready to fly.
  • Select CALIBRATE under AIRCRAFT STATUS | COMPASS. Click OK.
  • Confirm solid yellow rear lights.
  • Pick up the Mavic and turn it smoothly and steadily a full 360 degrees until the lights turn solid green.
  • Point the front of the Mavic 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.

If for any reason you do not complete any of the above steps smoothly and evenly, restart the process.

─────────────────────────────────────────────────────────
Note: A lot of this information was copied over from ianwood's thread in the Phantom Pilots forum.

Very helpful information and thanks for posting this information.

 

[MrMavic]

If I went by this, I would have to calibrate almost every time I flew, except for at home. I live 1/4 mile away from the mountains on flat valley floor, and here in Montana we're in and out of the mountains all the time. We have elevation changes of 6000 feet in only a couple of miles of travel in some areas.
Also, I'm adding and removing equipment all the time depending on where I fly .... Filters / Floaters for water / prop guards and other things.

 

[Inspirephil]

I very rarely have to do compass calibrations! Only in extreme circumstances and even then only because I have changed locations by a long distance from home or my last place that I flew.

 

[DanMan32]

Whatever your take on compass calibration, you do need to be careful not to make a worse calibration by being within magnetic interference. There is a certain tolerance before you'll be notified of a problem.