Vehicle compass system

  • US 5,761,094 A
  • Filed: 01/18/1996
  • Issued: 06/02/1998
  • Est. Priority Date: 01/18/1996
  • Status: Expired due to Term
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First Claim
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1. An electrical compass system for a vehicle, comprising:

  • a magnetic field sensor for detecting the earth'"'"'s magnetic field and for providing electrical signals representative thereof;

    a processing circuit coupled to said sensor for processing said electrical signals from said sensor and for providing display output signals in response thereto representative of the vehicle heading, said processing circuit including a calibration routine for correcting for display errors due to vehicle magnetism, said calibration routine re-calibrates the compass system based upon the electric signals output from said magnetic field sensor;

    a display circuit coupled to said processing circuit and responsive to said display output signals for displaying the vehicle heading; and

    said processing circuit monitoring said electrical signals from said sensor and reinitializing said calibration routine when said processing circuit determines that the detected signal levels from said sensor have shifted such that said signal levels are outside of a variable threshold, said processing circuit varying said variable threshold in response to a sensed chance in the strength of the earth'"'"'s magnetic field so as to maintain said variable threshold at a level that is a predetermined multiple of the strength of the earth'"'"'s magnetic field.

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