Magnetometer having a dynamically adjustable bias setting and electronic vehicle compass incorporating the same
First Claim
1. A magnetometer comprising:
- a resonant sensor for sensing a magnetic field, said sensor generating an output signal having a signal characteristic that varies in response to the sensed magnetic field;
an excitation circuit coupled to said resonant sensor for supplying an excitation signal thereto, said excitation circuit limits the amplitude of the excitation signal to prevent significant saturation of the response of said resonant sensor to the excitation signal; and
a processor coupled to receive the output signal from said sensor, said processor determines the magnetic field component sensed by said sensor.
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Abstract
According to some embodiments of the present invention, a magnetometer includes at least one sensor for sensing a magnetic field component, a biasing circuit, and a processor. The sensor generates an output signal having a signal characteristic that varies in response to the sensed magnetic field component and in response to an applied bias. The biasing circuit dynamically biases the sensor in response to a bias setting signal. The processor is coupled to receive the output signal from the sensor and coupled to the biasing circuit. The processor is operable to generate the bias setting signal and thereby control the biasing circuit to dynamically bias the sensor such that the signal characteristic of the output signal is maintained in a target range. The processor determines the magnetic field component sensed by the sensor as a function of the bias setting applied to the sensor.
75 Citations
24 Claims
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1. A magnetometer comprising:
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a resonant sensor for sensing a magnetic field, said sensor generating an output signal having a signal characteristic that varies in response to the sensed magnetic field;
an excitation circuit coupled to said resonant sensor for supplying an excitation signal thereto, said excitation circuit limits the amplitude of the excitation signal to prevent significant saturation of the response of said resonant sensor to the excitation signal; and
a processor coupled to receive the output signal from said sensor, said processor determines the magnetic field component sensed by said sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An electronic compass for a vehicle comprising:
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a first resonant magnetic field sensor for sensing a first component of a magnetic field;
a second resonant magnetic field sensor for sensing a second component of the magnetic field that is orthogonal to the first component, each of said sensors generating an output signal having a signal characteristic that varies in response to both the sensed component magnetic fields;
an excitation circuit coupled to said first and second resonant magnetic field sensors for supplying an excitation signal thereto, said excitation circuit limits the amplitude of the excitation signal to prevent significant saturation of the response of said resonant sensor to the excitation signal; and
a processing circuit is coupled to receive the output signals from said sensors to determine the magnetic field components sensed by said sensors, said processing circuit computes a vehicle heading as a function of the sensed magnetic field components; and
a heading indicator coupled to said processing circuit for indicating the vehicle heading.
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17. A magnetometer comprising:
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a resonant sensor for sensing a magnetic field, said sensor generating an output signal having a signal characteristic that varies in response to the sensed magnetic field and in response to an applied bias;
a biasing circuit for adjustably biasing said sensor at two or more bias levels; and
a processor coupled to receive the output signal from said sensor, said processor determines the magnetic field component sensed by said sensor, wherein the peak to peak excursion of the magnetic field level in said resonant sensor during a resonant cycle is a fraction of the field level excursion range due to the adjustment of the bias circuit over its total range of adjustment. - View Dependent Claims (18, 19, 20)
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21. A magnetometer comprising:
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a resonant sensor for sensing a magnetic field, said sensor generating an output signal having a signal characteristic that varies in response to the sensed magnetic field; and
a processor coupled to receive the output signal from said sensor, said processor determines the magnetic field component sensed by said sensor, wherein the peak to peak excursion of the magnetic field level in said resonant sensor during a resonant cycle is less than the total range of the magnetic field to be measured. - View Dependent Claims (22, 23)
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24. A magnetometer comprising:
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a sensor for sensing a magnetic field, said sensor generating an output signal having a signal characteristic that varies in response to the sensed magnetic field and in response to an applied bias;
a biasing circuit for adjustably biasing said sensor at two or more bias levels; and
a processor coupled to receive the output signal from said sensor, said processor determines the magnetic field component sensed by said sensor as a function of the signal characteristic of the output signal from said sensor and as a function of a slope of the output signal versus bias level.
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Specification