Magnetic field compensation system and method thereof
First Claim
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1. A compass system for a vehicle comprising:
- magnetic sensors mounted in the vehicle for sensing directional components of the Earth'"'"'s magnetic field vector, wherein each of said magnetic sensors output signals representing a sensed component of the Earth'"'"'s magnetic field along with components of any electromagnetic noise;
a processing circuit coupled to said magnetic sensors for receiving the output signals, said processing circuit being programmed to execute the steps comprising;
computing a first average of the output signals,determining whether a source of electromagnetic interference is activated,computing a first calibration point responsive to the output signals,while a source of electromagnetic interference is activated, computing second average of the output signals acquired after activation of the source of electromagnetic interference, computing a difference between the second average of the output signals from the first average to compute an offset vector, and computing a second calibration point by offsetting the first calibration point by the offset vector, andcomputing a heading of the vehicle using the most recently acquired output signals and one of the first calibration point and the second calibration point and generating a heading signal indicative of the heading; and
a heading indicator coupled to said processing circuit for receiving the heading signal and for indicating the heading to a driver of the vehicle.
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Abstract
A compass system configured to compensate for electromagnetic interference in a vehicle is provided that includes an electronic device that is sensitive to electromagnetic interference (EMI), wherein the electronic device is positioned in a vehicle such that the electronic device receives EMI from another accessory in the vehicle, and wherein the electronic device is configured to compensate for the EMI, such that the EMI field caused by the accessory can be detected and added to existing calibration point while the accessory is powered on.
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Citations
20 Claims
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1. A compass system for a vehicle comprising:
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magnetic sensors mounted in the vehicle for sensing directional components of the Earth'"'"'s magnetic field vector, wherein each of said magnetic sensors output signals representing a sensed component of the Earth'"'"'s magnetic field along with components of any electromagnetic noise; a processing circuit coupled to said magnetic sensors for receiving the output signals, said processing circuit being programmed to execute the steps comprising; computing a first average of the output signals, determining whether a source of electromagnetic interference is activated, computing a first calibration point responsive to the output signals, while a source of electromagnetic interference is activated, computing second average of the output signals acquired after activation of the source of electromagnetic interference, computing a difference between the second average of the output signals from the first average to compute an offset vector, and computing a second calibration point by offsetting the first calibration point by the offset vector, and computing a heading of the vehicle using the most recently acquired output signals and one of the first calibration point and the second calibration point and generating a heading signal indicative of the heading; and a heading indicator coupled to said processing circuit for receiving the heading signal and for indicating the heading to a driver of the vehicle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A compass system for a vehicle comprising:
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magnetic sensors mounted in the vehicle for sensing directional components of the Earth'"'"'s magnetic field vector, wherein each of said magnetic sensors output signals representing a sensed component of the Earth'"'"'s magnetic field along with components of any electromagnetic noise, said magnetic sensors including an X-axis sensor, a Y-axis sensor, and a Z-axis sensor, wherein the X- and Y-axis sensors are positioned in a generally horizontal plane with axes that are perpendicular to one another, and wherein the Z-axis sensor is positioned to sense generally vertical magnetic field components; a processing circuit coupled to said magnetic sensors for receiving the output signals, said processing circuit being programmed to execute the steps comprising; computing a first calibration point responsive to the output signals, determining whether a source of electromagnetic interference is activated by monitoring the output signal of said Z-axis sensor for variations, while a source of electromagnetic interference is activated, computing a second calibration point by offsetting the first calibration point by an offset vector, and computing a heading of the vehicle using the most recently acquired output signals and one of the first calibration point and the second calibration point and generating a heading signal indicative of the heading; and a heading indicator coupled to said processing circuit for receiving the heading signal and for indicating the heading to a driver of the vehicle. - View Dependent Claims (15, 16, 17)
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18. A compass system for a vehicle comprising:
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magnetic sensors mounted in the vehicle for sensing directional components of the Earth'"'"'s magnetic field vector, wherein each of said magnetic sensors output signals representing a sensed component of the Earth'"'"'s magnetic field along with components of any electromagnetic noise; a processing circuit coupled to said magnetic sensors for receiving the output signals, said processing circuit being programmed to execute the steps comprising; determining whether excessive noise is present in the output signals based upon a noise threshold, determining whether windshield wipers have been activated, computing a first calibration point responsive to the output signals when excessive noise is not present, when the windshield wipers have been activated, changing the noise threshold such that electromagnetic noise generated by the windshield wipers does not cause said processing circuit to determine that excessive noise is present, and computing a heading of the vehicle when excessive noise is not present using the most recently acquired output signals and the first calibration point and generating a heading signal indicative of the heading; and a heading indicator coupled to said processing circuit for receiving the heading signal and for indicating the heading to a driver of the vehicle. - View Dependent Claims (19, 20)
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Specification