EMSIS – User’s and Installation Manual
Please make sure that airplane is level for both, roll and pitch. Make also sure that EMSIS unit is turned
ON for at least five minutes – this warms up the internal electronics and stabilizes numerical filters.
Once the airplane is level and steady, select the AHRS level option to start the automatic calibration
procedure. Window illustrated on Figure 26 opens.
Figure 26: Calibrating the AHRS level.
Wait for the progress bar to finish and observe the roll and pitch numerical values. At the end they should
be close to zero. Close the window. This also stores new values.
6.9.3 Compass Calibration
This option is available only when MAGU (electronic magnetic compass) is also present on the CAN bus.
Before you do the calibration, you need to finish the AHRS calibration. Compass and AHRS work in pair
and information from AHRS greatly increases the precision of compass. Please, also make sure that the
system is running at least for 15 minutes. This time is required to warm up the electronic and stabilize the
numerical filters.
Figure 27: Calibrating Magu, situation before rotating (left) and after full rotation (right).
When ready, you need to rotate the aircraft for cca 400 degrees. Direction of rotation and start azimuth are
not important. When rotating, try to keep a steady pace for the best results – this will result in a constant
angular velocity. When turning aircraft, the progress bar grows and the procedure is complete when it
reaches full. You have to make more than a full circle because the initial readings are not used in
computation.
At this point a blue ellipse is drawn on the chart. Corrections up to 15 degrees are generally accepted as
appropriate. If you constantly get correction curve larger than 15-20 degrees, then you probably need to
find a better location for Magu. The correction on Figure 27 reaches cca 8 degrees.
Important:
If you are happy with the results, you must close the window using the
check
button.
This
will also save the results. Closing with the
cross
button does not save the results.
6.9.4 Compass Offset
The procedure mentioned above removes most of the compass error and in most cases this is more than
enough. However, some constant error in all direction remains. You need to obtain this error by observing
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