Patent ID: 6192315
Filing Date: 2001-02-20
Classification: G01C

Abstract:
An electronic compass system for a vehicle comprising:a magnetic field sensor for detecting the earth's magnetic field and for providing electrical signals representing the direction of the vehicle in relation to the earth's magnetic field;a heading indicator for indicating vehicle headings in response to received vehicle heading signals; anda processor coupled to said magnetic field sensor for receiving said electrical signals and coupled to said heading indicator for supplying the vehicle heading signals to said heading indicator, said processor includingfirst compass control means for calculating vehicle headings in response to said received electrical signals using precalibration data to compensate for expected vehicular magnetism,second compass control means for calculating vehicle headings in response to said received electrical signals using an automatic calibration routine to compensate for actual vehicular magnetism, andcontrol transfer means for initially selecting the vehicle headings calculated by said first compass control means to be represented by the vehicle heading signal supplied to said heading indicator, and for selecting the vehicle headings calculated by said second compass control means after the automatic calibration routine has acquired sufficient data from said magnetic field sensor to calibrate the compass system.