Accuracy of GpsLocation.Heading on Windows Mobile

I've been use GpsLocation.Heading to get the current direction/orientation of my device.

But it seems not accurate, where the value is either:

• keep changing with a huge difference even I just put the device on the table without moving it
• or the value didn't change even I move around and rotate the device.

means, it was very inconsistent and inaccurate.

As, I believe, from the documentation, Heading suppose to give me the value(in degrees) of where my device currently heading.

Does anybody know how to use it properly, or how to get the accurate value?

This heading will only be accurate when you move.

Look for a magnetic field sensor (compass) (if any) in the device and then use that.