Digital compass
The compass offers an additional benefit especially in the USA. In large cities the streets are frequently arranged according to the points of the compass. The signposts are also specified with points of the compass.
However, the compass also assists orientation in large European cities on the basis of the points of the compass.
The magnetic field sensor is on the PCB in the inside mirror. The magnetic field sensor measures the current alignment of the magnetic field.
The control electronics for the compass are integrated into the printed circuit board for the inside mirror. The signals from the magnetic field sensor are received by the control electronics. The liquid crystal display is activated directly by the control electronics.
The following system functions for the digital compass are described:
- Display
The point of the compass is displayed in transparent light technology in the inside mirror. The display is at the top right in the inside mirror. The display is divided into eight compass points. The display is available in English and German (delivery status: English LHD)
N: North
NE: North East (German: NO)
E: East (German: O)
SE: South East (German: SO)
S: South
SW: South West
W: West
NW: North West
The changeover between displays is carried out as follows:
- The current vehicle position is the center of a 360° circle.
- The eight points of the compass divide these 360 degrees into sixteen 22.5 degree segments.
- The display changes over if the direction of travel changes by more than 22.5°.
- Brightness control of display
2 photocells in the electrochromic inside mirror record the ambient brightness (1 photocell for the ambient brightness coming from the front, 1 photocell for the ambient brightness coming from the rear). The photocells deliver the signals for the display brightness control. The brightness of the display is adjusted by the inside mirror control electronics to suit the ambient brightness.
- Adjustment of magnetic field zones and calibration
The worldwide magnetic field zones are permanently stored in the inside mirror. The magnetic field zones represent the deviations in relation to an ideal magnetic field for earth. The orientation "North" is precisely determined by the magnetic field zones. The current magnetic field zone may be adjusted according to the geographic location. For example, Germany is located in magnetic field zone "8".
A vehicle has its own magnetic field. This makes it possible for the magnetic field sensor to measure an overlapping of the magnetic field with the Earth's magnetic field. This overlapping is "worked out" by calibrating the compass.
A changed magnetic field is normally calibrated "automatically". The vehicle's magnetic field may change under the following special circumstances:
- Powerful vibration during an accident
- Very large external magnetic field - e.g. if a vehicle passes under a train when travelling through an underpass
We can assume no liability for printing errors or inaccuracies in this information and reserve the right to introduce technical modifications at any time.