COMPASS SYSTEM AND COMPONENTS THEREFOR HAVING AUTOMATIC FIELD CANCELLATION

• US 3,678,593 A
• Filed: 12/26/1968
• Issued: 07/25/1972
• Est. Priority Date: 12/26/1968
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Donald H. Baker, Frank H. Kallio
• Inventors: Baker, Donald H., Kallio, Frank H.
• Primary Examiner(s): Hull, Robert B.
• Application Number:
  US04/787,143
• Time in Patent Office: 1,307 Days
• Field of Search: 33/204.43,204.44,222.7,222.75 324/43
• US Class Current: 33/361
• CPC Class Codes: G01C 17/30 Earth-inductor compasses
• CPC Class Codes: G01R 33/025 Compensating stray fields G01R33/0017 takes precedence

Abstract

A compass system utilizing a flux valve responsive to the earth'"'"''"'"'s magnetic field in which the earth'"'"''"'"'s field vector sensed by pick-up windings is resolved into component values that are converted to proportional DC currents from an infinite impedance current source that is independent of the load of the pick-up windings, these currents being fed back into the flux valve in a direction to cancel the earth'"'"''"'"'s field vector whereby to drive the flux valve output towards null.

Claims

1. In a magnetic compass system for navigable craft, the combination comprising, detector means including a plurality of pick-up windings responsive to the direction of the earth'"'"''"'"'s magnetic field relative thereto for providing a first plurality of alternating signals representative of respective vector components thereof, demodulating means responsive to said plurality of signals for providing DC voltage signals corresponding respectively thereto, said signals constituting system output voltage signals adapted to energize utilizing apparatus, means responsive to said demodulating means for converting said DC voltage signals to proportional d.c. current signals, said last-mentioned means constituting an infinite impedance current source independent of the impedance of said pick-up windings, and means supplying said DC current signals back to said pick-up windings for producing magnetic field components at said detector means corresponding to but opposing said earth'"'"''"'"'s field components and indepeNdent of the impedance of said pick-up windings.

2. In a magnetic compass system of the character recited in claim 1, said converting means including first and second channels for feeding back first and second signals to said pick-up windings in the form of DC currents.

3. In a magnetic compass system of the character recited in claim , said converting means including compensation means for providing a specified ratio between said first and second signals which provides cancellation of differential levels in said DC output signals.