I have a APEX 13 that is only used for Mega 360 Imaging. Also have an external GPS/Heading sensor mounted, but cannot find any instructions about calibrating the heading sensor with an APEX. The sensor plugs directly into the back of the APEX, so I do not have a NMEA network. The manual that comes with the sensor has calibration instructions for the Helix and Solix only. Any information would be appreciated. Thanks.