One powerful feature when it comes to heading estimation is Active Heading stabilization (AHS). AHS
uses the magnetometers to estimate the gyro bias, but it does not reference the heading. This way,
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. When the magnetic field is disturbed, AHS will still function. The
frequency though of the updates of the gyr o bias will be lower, as AHS is triggered only when the
magnetic field is stable.
There is one known situation where AHS will have a detrimental effect on the performance. When the
magnetic field is changing very slowly (e.g. when an object is rotating slowly, less than e.g. 0.5 deg/s), AHS might estimate the gyro 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
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.