Method and system for electronic compass calibration and verification
First Claim
1. A system comprising:
- a first magnetometer that produces a first output signal;
a second magnetometer that produces a second output signal;
an analog-to-digital signal converting means coupled to the first and second magnetometers, wherein the analog-to-digital signal converting means converts (i) the first output signal to a first digital signal, and (ii) the second output signal to a second digital signal;
a processor that receives the first digital signal and the second digital signal; and
a network that includes a coil located in proximity to the first and second magnetometers, wherein (i) the network is coupled to the processor, (ii) the processor provides a first voltage signal at the network for producing a first self-trimming current, and (iii) the coil generates a magnetic field in the vicinity of the first and second magnetometers when the first self-trimming current passes through the coil.
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Accused Products
Abstract
A method and system for calibrating a magnetic compass and/or verifying a compass calibration, using a calibration magnetic field produced by a field-generating coil within the magnetic compass is described. The field-generating coil is located near magnetometers within the magnetic compass. Passing a self-trimming current through the coil produces a magnetic field that acts on the magnetometers. Samples of an output signal from each magnetometer are taken to obtain digital values that indicate the output signal from each magnetometer. The digital values are used by a processor to determine one or more calibration coefficient for using calibrating the magnetic compass. The samples of the output signals are taken when a self-trimming current is passing through the coil and when the self-trimming current is not passing through the coil. Calibration of the compass occurs by applying the one or more calibration coefficients to subsequent signals that indicate the output signals of one or more of the magnetometers.
30 Citations
34 Claims
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1. A system comprising:
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a first magnetometer that produces a first output signal; a second magnetometer that produces a second output signal; an analog-to-digital signal converting means coupled to the first and second magnetometers, wherein the analog-to-digital signal converting means converts (i) the first output signal to a first digital signal, and (ii) the second output signal to a second digital signal; a processor that receives the first digital signal and the second digital signal; and a network that includes a coil located in proximity to the first and second magnetometers, wherein (i) the network is coupled to the processor, (ii) the processor provides a first voltage signal at the network for producing a first self-trimming current, and (iii) the coil generates a magnetic field in the vicinity of the first and second magnetometers when the first self-trimming current passes through the coil. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A system comprising:
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a first magnetometer that produces a first output signal; a second magnetometer that produces a second output signal; a first amplifier coupled to the first magnetometer for receiving the first output signal, wherein the first amplifier amplifies the first output signal to produce a first amplifier signal; a second amplifier coupled to the second magnetometer for receiving the second output signal, wherein the second amplifier amplifies the second output signal to produce a second amplifier signal; an analog-to-digital converter coupled to the first and second amplifiers, wherein the analog-to-digital converter converts the first amplifier signal to a first digital signal and coverts the second amplifier signal to a second digital signal; a processor that receives the first and second digital signals; and a network that includes a coil located in proximity to the first and second magnetometers, wherein (i) the network is coupled to the processor, (ii) the processor provides a voltage signal for producing a first self-trimming current, and (iii) the coil generates a magnetic field in the vicinity of first and second magnetometers when the first self-trimming current passes through the coil. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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24. A magnetic compass comprising:
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a first magnetometer that produces a first output signal; a second magnetometer that produces a second output signal; an amplification means coupled to the first magnetometer and the second magnetometer, wherein the amplification means (i) receives and then amplifies the first output signal to produce a first amplifier signal, and (ii) receives and then amplifies the second output signal to produce a second amplifier signal; an analog-to-digital signal converting means coupled to the amplification means, wherein the analog-to-digital signal converting means (i) receives and then converts the first amplifier signal to a first digital signal, and (ii) receives and then converts the second amplifier signal to a second digital signal; a processor that receives the first and second digital signals; and a network that includes a coil located in proximity to the first and second magnetometers, wherein (i) the network is coupled to the processor, (ii) the processor provides a voltage signal at the network for producing a first self-trimming current, and (iii) the coil generates a magnetic field in the vicinity of the first and second magnetometers when the first self trimming current passes through the coil. - View Dependent Claims (25, 26)
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27. In a magnetic compass that includes a processor, a coil coupled to the processor, at least first and second magnetometers, and an analog-to-digital signal converting means that converts at least a first analog signal produced by the first magnetometer to a first digital signal and a second analog signal produced by the second magnetometer to a second digital signal, a method of calibrating the magnetic compass comprising:
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driving the coil with a first voltage supplied by a first processor output so as to supply a first self-trimming current through the coil; reading values of the first and second digital signals, at the processor when driving the coil with the first voltage, to obtain a first digital value and a second digital value, respectively; reading values of the first and second digital signals, at the processor when not driving the coil with the first voltage, to obtain a third digital value and a fourth digital value, respectively; and determining a first calibration coefficient based on the first digital value, the second digital value, the third digital value, and the fourth digital value, for use in trimming at least one of the first and second digital signals. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34)
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Specification