Compensation system for electronic compass

  • US 6,173,501 B1
  • Filed: 09/08/1998
  • Issued: 01/16/2001
  • Est. Priority Date: 12/20/1991
  • Status: Expired due to Fees
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First Claim
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1. A method for calibrating a magnetoresistive sensor in a magnetic compass, said compass including an electronic circuit and a microcomputer for processing an output signal from said sensor, said sensor being alternately biased between a reset mode and a set mode, said method comprising the steps of:

  • measuring the value of the sensor output signal relative to an offset reference value in said reset mode and in said set mode, comparing the value of the sensor output signal in the reset mode with the value of said sensor output signal in the set mode, if the output signal has a value of zero in the reset mode at the same time it has an output voltage of zero in the set mode, maintaining the existing offset calibration value of the sensor without change, if the output signal during the reset mode has a non-zero value at a given time and the output signal during the set mode has the same non-zero value at said given time and both of said non-zero values are of the same sign, changing the offset calibration value of the sensor by adding a calibration value equal to a first predetermined fractional part of said non-zero value to a second predetermined fractional part of said existing offset reference value.

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