WP7 magnetometer data from 360 degree rotation

This post is a continuation with my unhealthy obsession with why the compass API on Windows Phone 7 doesn't actually point north.

I captured the following data rotating my Nokia Lumia 800 a full 360 degrees. Admittedly the rotation by hand so there is a fair bit of noise in the readings.

What it does show is:

1. the Magnetic Heading drastically changing when it reaches 256°
2. the declination changing from -129° to +127°

Magnetic versus True Heading

Scatter plot of magnetometer readings

Magnetometer Axis Readings by Bearing rotation - radar

Magnetometer Axis Readings by Bearing rotation - line

See also:

• Magnetometer Application on the WP7
• HTC Trophy 7 Compass Magnetic Declination gives incorrect True North