Electronics - Design And Function - 2 Of 4: Compass: Design: Calibration
Calibration of the compass is necessary for it to display the correct direction. During calibration, the compass detects the magnetic field from the vehicle, which must be taken into consideration when calculating the compass direction.
The compass must be calibrated when:
- the display does not show a compass direction within a couple of seconds. This may be due to a highly magnetic object being placed in the vicinity of the compass, such as an antenna
- the compass does not display the correct direction, even though the correct magnetic zone has been set.
The compass has two different calibration statuses:
- initial calibration status
- continuous calibration status.
On delivery from the manufacturer, the compass is in initial calibration status. The compass can also switch to initial calibration status if it is affected by a strong magnetic field. In this status, the character C appears in the display.
When the character C does not appear in the display, the compass is in continuous calibration status. The initial calibration is concluded and the compass now only performs fine adjustments to the calibration.
In continuous calibration status:
- the compass direction is calculated every 2 seconds, as long as the compass is not affected by a strong magnetic field
- the compass calibrates itself continually during normal driving
- if the vehicle is driven across a magnetic zone limit, the compass adjusts itself
- the compass compensates automatically for slow changes in the vehicle magnetism, which occur as the car gets older
- the compass detects and corrects itself for dramatic changes in the vehicle magnetism, for example when a magnetic antenna is installed near the compass
- the display is cleared if the compass detects a very strong magnetic field.