One powerful feature when it comes to heading estimation is Active Heading Stabilization (AHS). With AHS drift in heading can be as low as 1 deg after 60 minutes for the MTi 100-series and 3 deg after 60 minutes for the MTi 10-series. AHS can be a solution when the MTi is used in a disturbed magnetic field. AHS requires the MTi to be motionless for several (tens of) seconds.
There is one known situation where AHS will have a detrimental effect on the performance. When the application or the magnetic field rotates very slowly, the AHS algorithm may estimate the gyroscope bias incorrectly.
When AHS is applied to a filter profile that uses the magnetic field as a reference, the magnetic field will no longer be used as a reference. Heading output will be heading tracking instead of referenced heading.
AHS is off by default from firmware version 1.4.12. To enable AHS, enable AHS via SetOptionFlags.
The message for enabling AHS is FA FF 48 08 00 00 00 10 00 00 00 00 A1.