Tracker One/ Tracker SoM Eval "loc" heading IMU


I am working with the Tracker One & Tracker One SoM Eval board. I have successfully parsed the “loc” event. I would like to understand how the “hd” heading variable is calculated.

Is it derived from the IMU? or is it calculated from past GPS locations?

Does the mounting orientation of the Tracker One / Eval board matter to get a proper reading? In what orientation should the device be pointing to read 0 (North)?

I have a Tracker One / Tracker SOM Eval board sitting side by side, however they are reporting significantly different values.

Any insight is appreciated.

Thank you

The value of hd comes directly from point updates from the NEO-M8U GPS module, no additional processing past initial parsing. It isn’t immediately clear exactly what goes into that value on the NEO-M8U but I would guess some combination of successive GPS location and feedback from the IMU. Unfortunately, the naming in loc as hd may be misleading as it appears to be course-over-ground (so derived from motion) and not just orientation that would be expected in a heading.

If your units are stationary possible the differing values are coming from that. I expect once in motion they would read similarly.

I believe the heading (course) is dependent on the combination of successive points versus orientation. This is very likely, especially when the frame is not defined as it is in automotive models.