US 5,353,241 AGranted

Shifting system and method for an electronic compass system

OwnerRafi A. Al-Attarinventor

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Abstract

A shifting compensation circuit which employs a ranging circuit having a variable direct voltage source, to compensate for abnormally large vehicle magnetic fields. A ranging circuit is coupled between a microcomputer and a flux-gate. The microcomputer monitors the output of an integrator through a buffer amplifier to minimize variations in the integrator output caused by temperature variations, and directs the variable direct voltage source to add a direct voltage reference, in opposition to the vehicle's magnetic field signal and within the output voltage range of the integrator, to the output signal of the flux-gate, such that the combination of the two signals is within the output voltage range of the integrator for all vehicle headings.

Claims7

Dependent claims

In a control circuit for an electronic compass which includes a microcomputer, a flux gate having first and second sense coils each producing an output signal dependent upon sensed strengths of the earth's magnetic field and of a magnetic field associated with a vehicle upon which the flux gate is mounted, and an integrator having a fixed output voltage range, a shifting compensation circuit for bringing the output voltage of integrator within the fixed, allowable output voltage range of said integrator, the shifting compensation circuit comprising:

a ranging circuit coupled between said microcomputer and said flux gate;
said ranging circuit including a variable direct voltage source, said microcomputer directing said variable direct voltage source to add a designated direct voltage reference in opposition to a signal due to the vehicle's magnetic field, and within said fixed output voltage range of said integrator, to the output signal of the flux-gate.

Dependencies are inferred from the claim text.