why wont my compass calibrate?

[Fir3b1rd]

I have access to a fair amount of open space but in this part of Texas we also have a lot of limonite deposits. Usually you can't see them so you never know. In essence in would be like standing on a lump of iron. I guess this is a part of why we calibrate?

Fir3b1rd made me think also about the hardware in my knees. Never considered it. I assume most if not all of it is non-ferrous but I don't really know. If you are supposed to rid your self of keys etc. before calibrating.

Just thinking out loud........

not sure how titanium effects magnetism. I know that it does not very high in conductivity. that would lend to my issues there to, I have a TI plate in the head, my back is held together with it and so is my pelvis.

 

[stujol]

If you were using litchi to calibrate, it doesn't tell you to do the turns but the lights will flash. Just do the normal calibration dance and you will be good to go. I don't calibrate my self unless I travel more than 50 miles from my last calibration.

 

[Fir3b1rd]

If you were using litchi to calibrate, it doesn't tell you to do the turns but the lights will flash. Just do the normal calibration dance and you will be good to go. I don't calibrate my self unless I travel more than 50 miles from my last calibration.

thank you! that was a question I was considering also. I live in NOLA but my family has a placeon the beach about 55-60 miles away. I'm planning to fly there a lot over the summer .

 

[RedHotPoker]

To fly 50-60 miles, you will likely need several more batteries... ;-)

Eh, hahaha, yeah hehe too!!

Hope everything works out and you get that Phantom above the horizon...

RedHotPoker

 

[Meta4]

I have access to a fair amount of open space but in this part of Texas we also have a lot of limonite deposits.
Usually you can't see them so you never know. In essence in would be like standing on a lump of iron.
I guess this is a part of why we calibrate?

Your Phantom flies in the air, usually well up above the earth.
Unless you want to fly 6 inches above a deposit of Limonite or any other magnetic geology, you should not recalibrate your compass in the vicinity of any iron or steel (or iron ore)
You need your Phantom's compass to work properly in the normal magnetic field of the earth, not the distorted field close to a lump of iron.

Fir3b1rd made me think also about the hardware in my knees. Never considered it. I assume most if not all of it is non-ferrous but I don't really know. If you are supposed to rid your self of keys etc. before calibrating.

I'd be surprised if you have magnetic knees but you can easily tell by passing a cheap compass close to them to see if there is any deflection of the compass indicating a magnetic field

 

[RedHotPoker]

If you want to know if surgical stainless steel is ferrous, or what ever the implant is constructed of, hold a magnet to it...

RedHotPoker

 

[jack1144]

What Meta and many others have said. The compass doesn't need calibration every flight for me.
I have figured out how it works( mostly, I think). The compass needs to be accurate when your flying and calibrating on the ground while near magnetic/metal objects will throw off a perfectly good calibration. So how do know if something has affected the magnetometer in the aircraft?
Easy, point the aircraft to magnetic north while its 4feet above ground while level.
Read the x,y,z and mod values in the sensors section of the app.
The y should be very close to 0 (zero) the x will be positive near 500
Point south the y will be 0 and x close to -500( minus 500)
East and west the x and y swap values
If these are correct and its level, z will be around 1300 and mod 1500
No need to calibrate it knows it's directions.

 

[dbeavers]

Meta4

I was just musing about the extra bits I carry. MRI will make them shake but just enough to feel it. So not enough ferrous there to matter.

The limonite is very low grade in the iron ore world but there is a lot of it around, usually under 3-20 feet of blow sand. I really think it has minimal to no effect on compass function. I guess I could corner the local surveyor and get his take. I know when I was working 40 yrs ago for different surveyor using old school gear the lead guy never made mention of erratic compass behavior. But then I was just there to whack brush.

 

[jack1144]

Here's something you can try to show the effect of metal on the compass.
Set the craft on wooden table outside with no metal around.
You don't need to start the motors but start go app, remote and power craft on.
Go to sensors in app and rotate the craft until compass y=0 and x>400( not a minus number)
It's pointed north
Now bring a piece of metal near the craft, small, large and see how it affects the compass x,y,z and mod.
If you can do the same thing in parking area with no vehicles around, then drive your vehicle up very close.

 

[Sinisalo]

I know I have mentioned this before, but the dji firmware beta engineer's said it should be done before each start and flight. It came up when they were asked why most of the time the calibrate compass appears in the app menu even if the a/c had been calibrated. And before thry responded another person asked if it needed to be done every flight, or not. Their response was what I mentioned in the 1st sentence. They were asked why it does not say to do that in the manual or any place else, and that it would be nice if it did. And......like other stuff they never responded back.

My guess as to the reason why they say to calibrate before every flight is because the Magnetic Declination in any given area changes every year. In my location it changes 6 minutes every year so after 10 years I would be 1 degree off. You can use the calculator I posted above and just try to stay within 10 minutes (the calculator has an accuracy of +- 20 minutes so to stay at a half degree off or less you just keep the variance to 10 or under) So if I traveled to San Diego I would only have a magnetic declination variance of 2 minutes (+- 20 minutes). If I travel to Tampa I would have a magnetic declination variance of 17 degrees (+-20 minutes), not good!

Edit: FYI if you fly for 2 miles straight and are 30 minutes or .5 degree off, you will be 92 feet (28 meters) away from where your controller thinks you are. (assuming no gps signal)

 

[alokbhargava]

My guess as to the reason why they say to calibrate before every flight is because the Magnetic Declination in any given area changes every year. In my location it changes 6 minutes every year so after 10 years I would be 1 degree off. You can use the calculator I posted above and just try to stay within 10 minutes (the calculator has an accuracy of +- 20 minutes so to stay at a half degree off or less you just keep the variance to 10 or under) So if I traveled to San Diego I would only have a magnetic declination variance of 2 minutes (+- 20 minutes). If I travel to Tampa I would have a magnetic declination variance of 17 degrees (+-20 minutes), not good!

Edit: FYI if you fly for 2 miles straight and are 30 minutes or .5 degree off, you will be 92 feet (28 meters) away from where your controller thinks you are. (assuming no gps signal)

No this is not true.

If you got to move from point A to point B, GPS info is used to calculate direction to move and the direction is decided by the compass. Better the calibration for the direction at the location, faster it reaches the destination.

For the same reason, Stability at a point is affected if the compass is not correctly calibrated.

 

[Sinisalo]

No this is not true.

If you got to move from point A to point B, GPS info is used to calculate direction to move and the direction is decided by the compass. Better the calibration for the direction at the location, faster it reaches the destination.

as you can see at the end of my post I said "assuming no gps signal"

 

[alokbhargava]

as you can see at the end of my post I said "assuming no gps signal"

Yes if GPS signals are lost, it can not initiate it's return or may just fly over to unknown location. We don't know it's internal logic. But losing all the satellites should be a rare event.

Most susceptible element for the failures in the system is compass as it hangs on to the legs and Magnetics affect its calibration. I would suggest to calibrate every time you fly at a different location definitely or even at the same location how does it matter, it takes just few minutes.

 

[ianwood]

NASA, NOAA, the FAA and so on don't see any need to recalibrate their geomagnetic maps more than once every year...

...and neither should you UNLESS you have a reason for it. Good (and bad) reasons can be found here: Compass Calibration, A Complete Primer | DJI Phantom Forum

I just re-calibrated my Inspire Pros after several months on the same calibration. And that was only because I upgrade the firmware.

 

[John Locke]

I never recalibrate unless there's a good reason, such as new firmware or new location more than 50 miles east or west. There is always a risk of a new calibration being flawed, which is likely more risk than flying the existing calibration, assuming you haven't moved over 50mi.

 

[snerd]

I also subscribe to calibrating the compass infrequently. Once you have a "good" calibration, there is no need to re calibrate at every flight, unless moving hundreds of miles or after bumpy ride or crash.

 

[Fir3b1rd]

I'm disabled and so far had not problems calibrating the compass. Now this is not a necessity but I use a double turntable that rotates like a lazy susan plate. It performs the best possible calibration based on rotation. For the vertical turn I just lay the arms over the side and never have to worry where the props are located. I paid maybe $10 for it. You can under $5 and make one that's just a plate. Btw, my aircraft would not go up in the sky without a compass calibration 1st. I calibrate each fully charged battery just to play it safe.


View attachment 41470

this thing solved all my problems! thank you!!!!! loving the p3advanced!

 

[flyNfrank]

this thing solved all my problems! thank you!!!!! loving the p3advanced!

Show us a short video or a pic of what you have setup. Good to see it worked out for you.

 

[Fir3b1rd]

Show us a short video or a pic of what you have setup. Good to see it worked out for you.

I'll probably have it out tomorrow, I'll throw a pic up when I do!
I pretty much found a similar turntable to the one you posted on Amazon, I put the box on top and just follow the turn sequence. The box keep it flat when I lay it on its front to spin with a yard stick so that I'm not that close.


Sent from my iPad using Tapatalk

 

[flyNfrank]

I'll probably have it out tomorrow, I'll throw a pic up when I do!
I pretty much found a similar turntable to the one you posted on Amazon, I put the box on top and just follow the turn sequence. The box keep it flat when I lay it on its front to spin with a yard stick so that I'm not that close.


Sent from my iPad using Tapatalk

You don't have to answer, but is there a reason why you need to use a yard stick? (wheelchair?)