N017RW
Premium Pilot
Who actually calibrates their compass before every flight?
- Thread starter 0DRK3RT
- Start date
ianwood
Taco Wrangler
I calibrate if I move more than a degree on a map like this. Where you are matters. I doubt the calibration is any more accurate than a degree.
Oso
Premium Pilot
It's truly amazing that we have this exact same thread so many times, over and over again, each with effectively the exact same posts. I think this is the third compass calibration discussion in the last 5 days, one of which sprung from a checklist noting to calibrate every flight. Each discussion the same, with the same links to compass calibration info. Groundhog Day revisited.
The funny thing is that I continue to read them all, over and over again. Yes, I agree. Insanity.
The first step is admitting that I have a problem.
The funny thing is that I continue to read them all, over and over again. Yes, I agree. Insanity.
The first step is admitting that I have a problem.
I would suggest that this is sort of DJI's doing. It is the fact that the P3 manual states something that directly contradicts the best practices pulled together by a large group of experienced users here and elsewhere. And it can be fascinating to watch users cling to a single line in a vague and poorly written manual, instead of trying to understand what a compass calibration is and does.
- Joined
- Sep 8, 2015
- Messages
- 325
- Reaction score
- 156
Riddle me this: do I really need to recalibrate my compass after I install my Trackimo? Seems counterintuitive to do so with the tracker installed, as consensus is to not have your phone in your pocket when you do a calibration. The Trackimo is essentially a little phone, so wouldn't that screw up the process?
N017RW
Premium Pilot
Yes.
One of the often misunderstood purposes is to 'compensate out' all the fixed distortions from so-called soft and hard iron materials on the quad itself..
Aside from travel distances from last calibration place... compass compensation (calibration) for adding, removing, or relocating equipment on the craft is VERY important.
One of the often misunderstood purposes is to 'compensate out' all the fixed distortions from so-called soft and hard iron materials on the quad itself..
Aside from travel distances from last calibration place... compass compensation (calibration) for adding, removing, or relocating equipment on the craft is VERY important.
Last edited:
Adding or removing a component from the aircraft (especially an electronic one) is one of the few reasons one SHOULD do a compass calibration. By adding anything metallic to the aircraft (i.e. physically close to the compass module) you are changing the magnetic profile of the aircraft. The "compass dance" will teach the Phantom how to interpret magnetic north again, no matter its orientation.
Before the all-in-one camera drone approach that DJI has embraced with the Phantoms and the Inspire, changing cameras, and removing FPV transmitters, and changing out other components was a much more common activity, and led to lots of compass calibrations. The difficulty of getting a good cal that didn't result in "toilet-bowl effect" or a random drift used to be just as common a topic on old 3DR related forums as these calibration threads are here.
- Joined
- Sep 8, 2015
- Messages
- 325
- Reaction score
- 156
Soooo, I definitely should recalibrate it with my trackimo powered on and installed on my P3?
N017RW
Premium Pilot
Well that's a good question.
I have never had that situation but I'd go that way first and see what results you get (Mod value).
I have never had that situation but I'd go that way first and see what results you get (Mod value).
I would definitely re-calibrate if adding anything with a PC board and a battery to something the size of a Phantom. I know you know this, 0DRK3RT, but for the record, I would:
1)Cal in a known good magnetic environment
2)If Mod value isn't crazy, confirm that indicated aircraft direction on the app agrees with reality. (IMO, you should confirm this before takeoff on any flight, as this is the most obvious symptom of a compass calibration gone haywire.)
3) Once adequate satellites are acquired, take off and confirm stable hover. Fly and be happy.
4)Don't mess with it until necessary.
1)Cal in a known good magnetic environment
2)If Mod value isn't crazy, confirm that indicated aircraft direction on the app agrees with reality. (IMO, you should confirm this before takeoff on any flight, as this is the most obvious symptom of a compass calibration gone haywire.)
3) Once adequate satellites are acquired, take off and confirm stable hover. Fly and be happy.
4)Don't mess with it until necessary.
Yes I read that and it was very useful however didn't exactly explain the MOD value - sum of squares" from the X, Y and Z axes I get but what are those numbers telling us?
Even that description comes with the caveat: 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.
I'm new, so forgive me, but can we ever be 100% sure we have a good calibration until the point we have made a successful flight in a particular area?
It's a single value description of the total magnetic field, and you are correct that it doesn't necessarily confirm a good calibration. It can, however, be a good indicator of a completely nonsensical calibration (like if you calibrate on a steel dock). Calibrating over some rebar may or may not result in an "out-of-bounds" mod value, but could result in an offset in the compass' ability to find magnetic north in some axis, resulting in erratic flight.
So, yes. A successful flight is the only way to confirm a successful calibration, IMO. (Then don't mess with it unless you have to!)
- Joined
- Sep 8, 2015
- Messages
- 325
- Reaction score
- 156
Same thing over and over? Who uses carbon fiber props? What video editor do you use? The list goes on of questions asked every week.
Part of the problem is people reading the manual incorrectly or not remembering what they read. It reads as follows:
It _does not_ say to calibrate "every time". It's every new flight _location_. This might be a little vague but, as mentioned above, what area you are in general can change this distance. Some areas are more susceptible to a change in magnetic north (that is, the further you move north from the equator, the less you need to move to see the same difference.
Cold IMU calibration and compass calibration after every f/w update. I'll do the 'CC' Dance if I'm more than 2hrs drive from home, unless I don't.
Sometimes the area doesn't look like it's a good idea.
Sometimes the area doesn't look like it's a good idea.
Similar threads
