Garug,
I have not found analog encoders that have a pass-through which is needed for our design...
The documentation indicates that this value can be set by manual to identify a static frame azimuth.

Alex,
Is FRAME_HEADING_ANGLE implemented per the documentation? if I read it correctly this sounds like it would eliminate the need for a magnetometer in cases where the frame is static?

If I set FRAME_HEADING_ANGLE to the azimuth of the stationary frame (i.e. on a tripod) will that be used to prevent drift in frame and camera imu?

...
There are also a number of methods to manually correct gyro drift:
• Providing the heading angle from an external source. Via adjustable variable
"FRAME_HEADING_ANGLE" you can provide the heading angle to the controller. It will be translated
to the main IMU, if possible, and used as heading reference. The possible case where it may be
used: gimbal is mount statically, so the frame angle does not change. Or, gimbal is mounted on a
crane, and its azimuth is known from it's controller.
* This method is similar to CMD_AHRS_HELPER, but the reference vector is computed automatically from single variable taking into account frame's attitude.
...

thanks,
David