System using information on a communications bus to eliminate magnetic noise
First Claim
1. An electronic compass system for using information on a communications bus to eliminate magnetic noise comprising:
- a vehicle accessory having at least one electrical state, said vehicle accessory generating a known, consistent, magnetic field of an intensity sufficient to cause a static magnetic offset in said electronic compass;
an electronic controller coupled to said vehicle accessory, said electronic controller having logic operative to command said vehicle accessory to change electrical states, said electronic controller coupled to a communications bus and generating a vehicle event message corresponding to said electrical state;
a magnetic field sensor located in proximity to said vehicle accessory, said magnetic field sensor detecting a combination of Earth'"'"'s magnetic field and said known, consistent, magnetic field and generating a magnetic field signal wherein said Earth'"'"'s magnetic field is modified by said static magnetic offset;
a controller coupled to said magnetic field sensor and said communications bus, said controller receiving said magnetic field signal and said vehicle event message, said controller having control logic operative to receive said vehicle event message, lookup a predetermined correction factor for said vehicle event message stored in a memory location, and apply said predetermined correction factor to said magnetic field signal; and
a display coupled to said controller, said display displaying a heading unaffected by said static magnetic offset.
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0 Petitions
Accused Products
Abstract
An electronic compass system using information on a communications bus to eliminate magnetic noise which is integrated with an instrument cluster. A vehicle accessory, such as a blower motor, generates a known, consistent, magnetic field of intensity sufficient to cause a static magnetic offset in the electronic compass for each of its'"'"' electrical states. An electronic controller commands the vehicle accessory to change electrical states and transmits a vehicle event message on a communications bus. A magnetic field sensor detects a combination of Earth'"'"'s magnetic field and the stray magnetic field produced by the vehicle accessory. A controller is coupled to the communications bus and uses the vehicle event message to look up a predetermined correction factor, corresponding to the electrical state, to eliminate the effect of the static magnetic offset. The controller then displays a heading unaffected by the static magnetic offset.
19 Citations
15 Claims
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1. An electronic compass system for using information on a communications bus to eliminate magnetic noise comprising:
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a vehicle accessory having at least one electrical state, said vehicle accessory generating a known, consistent, magnetic field of an intensity sufficient to cause a static magnetic offset in said electronic compass;
an electronic controller coupled to said vehicle accessory, said electronic controller having logic operative to command said vehicle accessory to change electrical states, said electronic controller coupled to a communications bus and generating a vehicle event message corresponding to said electrical state;
a magnetic field sensor located in proximity to said vehicle accessory, said magnetic field sensor detecting a combination of Earth'"'"'s magnetic field and said known, consistent, magnetic field and generating a magnetic field signal wherein said Earth'"'"'s magnetic field is modified by said static magnetic offset;
a controller coupled to said magnetic field sensor and said communications bus, said controller receiving said magnetic field signal and said vehicle event message, said controller having control logic operative to receive said vehicle event message, lookup a predetermined correction factor for said vehicle event message stored in a memory location, and apply said predetermined correction factor to said magnetic field signal; and
a display coupled to said controller, said display displaying a heading unaffected by said static magnetic offset. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for using information on a communications bus to eliminate magnetic noise in an electronic compass comprising the steps of:
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generating a known, consistent, magnetic field of an intensity sufficient to cause a static magnetic offset in said electronic compass, said known, consistent magnetic field corresponding to at least one electrical state of a vehicle accessory;
commanding said vehicle accessory to change electrical states;
generating a vehicle event message, corresponding to said electrical state;
detecting a combination of Earth'"'"'s magnetic field and said known, consistent, magnetic field wherein said Earth'"'"'s magnetic field is modified by said static magnetic offset to generate an magnetic field signal;
receiving a vehicle event message corresponding to said electrical state;
looking up a predetermined correction factor for said vehicle event message stored in a memory location;
applying said predetermined compensation factor, corresponding to said vehicle event message, to said magnetic field signal; and
displaying a heading unaffected by said static magnetic offset. - View Dependent Claims (9, 10)
determining a maximum positive magnetic offset of said vehicle accessory;
determining a maximum negative magnetic offset of said vehicle accessory; and
scaling said compensation factor based upon said maximum and minimum magnetic offsets.
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11. An electronic compass system using information on a communications bus to eliminate magnetic noise comprising:
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a vehicle having an instrument panel an instrument cluster located in said instrument panel;
a vehicle accessory having at least one electrical state and generating a corresponding known, consistent, magnetic field of an intensity sufficient to cause a static magnetic offset in said electronic compass;
an electronic controller located in said vehicle and coupled to said vehicle accessory, said electronic controller having logic operative to command said vehicle accessory to change electrical states, said electronic controller coupled to a communications bus and generating a vehicle event message corresponding to said electrical state;
a magnetic field sensor located in said instrument cluster and in proximity to said vehicle accessory, said magnetic field sensor detecting a combination of Earth'"'"'s magnetic field and said known, consistent, magnetic field and generating a magnetic field signal wherein said Earth'"'"'s magnetic field is modified by said static magnetic offset;
a controller located in said instrument cluster and coupled to said magnetic field sensor and said communications bus, said controller receiving said magnetic field signal and said vehicle event message, said controller having control logic operative to receive said vehicle event message, lookup a predetermined correction factor for said vehicle event message stored in a memory location, and apply said predetermined correction factor for said magnetic field signal; and
a display located in said instrument cluster and coupled to said controller, said display displaying a heading unaffected by said static magnetic offset. - View Dependent Claims (12, 13, 14, 15)
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Specification