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[ianwood]

Loosen the 4 screws.

Turn the compass to the degree required.

Tighten the compass so it doesn't move easily.

Wedge something (i used carboard) tightly in the opening behind compass. You will see you can fit a piece nivley in there as the leg is hollow.

Tighten.

Enjoy nice solid hovering.

You may want to add a few caveats:

1. Make sure the screwdriver you use is not magnetized (many are).
2. If not sufficiently torqued and ideally given a small dab of blue Loctite, the tiny compass screws WILL back out. If your compass comes loose in flight, you will crash.
3. Rotating the compass will have a big impact on flight control. Do so carefully lest you suffer a flyaway.
4. Rotating the compass on the P2 and P2V does not fix declination problems.

I am curious to know what the differences are to the P1. On the P2x, shimming by 1x local declination will help but does not fix the problem. Shimming by 2x local declination will start out great but after a few minutes, it will start to over correct.

What I can tell so far is the P2x starts off thinking true north and magnetic north are the same (i.e. no auto-declination). You can demonstrate this easily using course lock. Take off and without any other inputs, switch to course lock and go straight. Course lock is reflection of the difference between the raw compass heading vs. the GPS heading during flight.

During flight, the Naza will recognize the discrepancy between compass and GPS heading and will slowly adjust the compass heading towards the GPS heading. It is an adaption like an ECU in a car (e.g. throttle adaption). After several minutes, the adaption will have the compass and GPS heading in agreement. The problem is when you turn off the P2x, the adaption is completely lost. There is no non-volatile adaption that I can detect (i.e. every flight starts the same way).

Bottom line for the P2x, this is a defect with a trivial software fix and rotating the compass is a crappy workaround that doesn't really work.

 

[ianwood]

There is an additional theory that the P2x Naza does have auto-declination but it is signed incorrectly e.g. instead of automatically applying 12 degrees here in Los Angeles which would eliminate all declination issues, it is applying -12 degrees which is effectively making it twice as bad.

This would explain why some people find that shimming by 2x will work better than 1x. Furthermore, if the signing is inconsistent in the code, it would also explain why shimming 2x declination only works for a short while before the adaption over corrects. It would also explain why my course lock is off by roughly 20+ degrees to the left.

 

[joeflyer]

Look at the manual. The fix is to rotate the GPS module, not the compass.

You're probably looking at the Naza manual. The standard Naza puck had the compass and gps in the same module. That's not how the phantom is set up, the gps and compass are separated.

Rotating a GPS antenna/receiver itself does nothing, there is no orientation to it. What they want you to do is rotate the compass, but on non-phantoms you can only do that by rotating the entire puck. On the phantom you can just rotate the compass itself.

Yes, I was looking at the NAZA Manual. Thanks for your explanation.

 

[Eos630]

Loosen the 4 screws.
Turn the compass to the degree required.
Tighten the compass so it doesn't move easily.
Wedge something (i used carboard) tightly in the opening behind compass. You will see you can fit a piece nivley in there as the leg is hollow.
Tighten.
Enjoy nice solid hovering.

You say it's working for you so, great! Your method for rotating the compass is not super solid, though.

a) You aren't getting much bite on the screws that hold the compass bracket.
b) Vibration will get hold of the screws and probably the cardboard after a while.
c) You didn't rotate the compass with any precision. More of a "There. That looks like about 14º" (or whatever your declination is.)

My P2 hasn't ever had a problem with stable hover. I don't think declination is so closely related to that. I think in your case it was more a matter of finally getting good IMU and compass calibration.