Patent Document ID: 4546551
Application ID: 06478364
Patent Status: 1

Claim One:
1. An electrical compass system for a vehicle, said system including sensing means for sensing a magnetic field and providing output signals representative thereof, circuit means coupled to said sensing means for providing display output signals, and display means coupled to said circuit means and responsive to said display output signals for displaying the sensed magnetic field; wherein the improvement comprises compensation means for correcting the sensed and displayed magnetic field for a steady state local magnetic field interference; said compensation means comprising: means coupled to said circuit means for establishing a predetermined display output signal when said sensing means is positioned in predetermined alignment with a known magnetic field; comparing means coupled to said sensing means and to said circuit means for comparing signals from said sensing means and said display output signals and applying a control signal to said circuit means when signals from said sensing means correspond to a direction which differs from said predetermined display output signal; and means coupled to said circuit means and to said sensing means for applying a correction signal to said sensing means and said correction signal generated by said circuit means in response to said control signal from said comparing means to cause said predetermined display output signal to occur.