Electronic compass

  • US 5,924,212 A
  • Filed: 10/06/1997
  • Issued: 07/20/1999
  • Est. Priority Date: 10/09/1996
  • Status: Expired due to Fees
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First Claim
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1. An electronic compass comprising:

  • at least two coil assemblies having magnetic axes which are oriented at a known angle to each other, each said coil assembly having at least a pair of substantially identical coils having magnetic axes that are parallel in a reverse sense, each of said coils having an inductance which varies as a function of the strength of a magnetic field in which it is positioned;

    at least one oscillator having frequencies of oscillation which are at least partially dependent upon the inductances of said coils;

    a coil bias current source which causes current to flow in said coils;

    at least one switch which alternatingly couples said coil bias current source to each of said coils of said coil assemblies; and

    ,a processor electrically coupled to said at least one switch which analyzes said frequencies of oscillation of said at least one oscillator when each of said coils of said coil assemblies is coupled to said coil bias current source and computes geographic orientation based upon said analysis.

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