LXNAV LX8000, User Manual

Page: 104 / 110

LX8000 (LX8080) Version 2.6 September 2011
Page 104 of 110
10.5 Compass Module
The compass module is an electronic compass device (magnetic field sensor) which was
developed for the LX8000. The LX8000 recognises the compass module automatically when
it is plugged into the RS485 bus. The only configuration settings needed are related to the
compensation procedure. An indication that the compass module is connected is the
appearance of raw data readings in the compass calibration page.
The heading indication is by default true. After change of settings in
UNITS
the
indicated heading may be magnetic heading.
The compass module not only permits the display of magnetic heading but also permits the
calculation of the wind vector in straight flight. The wind vector is calculated using the
triangle of velocities method where the vectors of ground speed with track, TAS with
compass heading and the wind vector form a triangle of velocities. The angular difference
between HDG and TRK depends on the magnitude of the wind vector and is normally quite
small which means that the measurement has to be quite precise if accuracy is to be
achieved. While the GPS data (TRK and GS) is precise small inaccuracies in the heading of
about 5° can cause errors of up to 25 km/h in the wind strength. This method only works
during straight flight and the calculation is stopped as soon as HDG and TAS change rapidly
such as when the glider is turning.
Sensor
Power supply