| 摘要 |
The apparatus detects the direction angle of a vehicle in order to compensate the error of an absolute position caused by a long drive in a vehicle navigation system. The apparatus comprises an oscillator(1) generating 1st signals with a frequency, and signals inverted from the 1st signals; a terrestial magnetic sensor(2) generating signals corresponding to the difference between the direction of the terrestrial magnetic field and the direction of the current vehicle drive; a sensor driver(3) driving the sensor(2) by the signals divided from the output of the oscillator(1); a 1st phase detector(4) detecting the phase difference between the direction of the terrestrial magnetic field and a 1st reference axis of the vehicle; a 2nd detector(5) detecting the phase difference between the direction of the terrestrial magnetic field and a 2nd axis perpendicular to the 1st reference axis; amplifiers(6,7); switching means(8,9); integrators(10,11).
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