Signal processor for use in electronic compass
First Claim
1. A signal processor for use in an electronic compass for processing signals from a geomagnetic compass sensor detecting sine or cosine wave signals induced by a drive signal according to an azimuth angle, said signal processor comprising:
- an analog signal processor for amplifying the signals from the geomagnetic compass sensor, canceling an offset voltage generated during an amplification process in response to an offset control signal, and controlling an amplitude of a signal in which the offset voltage is cancelled out in response to a gain control signal;
an analog/digital (AD) converter for converting analog signals from the analog signal processor into a digital signal; and
a digital signal processor for measuring a maximum value and a minimum value associated with the digital signal from the AD converter, determining the offset voltage and the amplitude on the basis of the maximum and minimum values, and outputting, to the analog signal processor, the offset control signal to be used for canceling the determined offset voltage and the gain control signal to be used for controlling the determined amplitude so that the amplitude lies within an allowable input range for the AD converter;
wherein the analog signal processor comprises;
a chopper for detecting the signals from the geomagnetic compass sensor;
an input amplifier for amplifying the detected signals output from the chopper on the basis of a preset gain;
a low pass filter for carrying out a preset low pass filtering operation for a signal output from the input amplifier;
an offset controller for generating a canceling voltage for canceling the offset voltage in response to the offset control signal and providing the generated canceling voltage to input terminals of the input amplifier; and
an automatic gain control (AGC) amplifier for setting an amplification gain in response to the gain control signal and amplifying a signal from the low pass filter in response to the set amplification gain.
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Accused Products
Abstract
In a signal processor for use in an electronic compass for controlling an offset voltage generated in an analog signal process and automatically controlling an amplification gain, an analog signal processor 52 amplifies signals Sx and Sy, and controls an offset voltage and amplitude A generated during an amplification process. An analog/digital (AD) converter 53 converts analog signals Vadcx and Vadcy from the analog signal processor 52 into a digital signal. A digital signal processor 54 measures a maximum value Vadc
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Citations
15 Claims
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1. A signal processor for use in an electronic compass for processing signals from a geomagnetic compass sensor detecting sine or cosine wave signals induced by a drive signal according to an azimuth angle, said signal processor comprising:
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an analog signal processor for amplifying the signals from the geomagnetic compass sensor, canceling an offset voltage generated during an amplification process in response to an offset control signal, and controlling an amplitude of a signal in which the offset voltage is cancelled out in response to a gain control signal;
an analog/digital (AD) converter for converting analog signals from the analog signal processor into a digital signal; and
a digital signal processor for measuring a maximum value and a minimum value associated with the digital signal from the AD converter, determining the offset voltage and the amplitude on the basis of the maximum and minimum values, and outputting, to the analog signal processor, the offset control signal to be used for canceling the determined offset voltage and the gain control signal to be used for controlling the determined amplitude so that the amplitude lies within an allowable input range for the AD converter;
wherein the analog signal processor comprises;
a chopper for detecting the signals from the geomagnetic compass sensor;
an input amplifier for amplifying the detected signals output from the chopper on the basis of a preset gain;
a low pass filter for carrying out a preset low pass filtering operation for a signal output from the input amplifier;
an offset controller for generating a canceling voltage for canceling the offset voltage in response to the offset control signal and providing the generated canceling voltage to input terminals of the input amplifier; and
an automatic gain control (AGC) amplifier for setting an amplification gain in response to the gain control signal and amplifying a signal from the low pass filter in response to the set amplification gain. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A signal processor for use in an electronic compass for processing a signal from a geomagnetic compass sensor, said signal processor comprising:
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a chopper for detecting the signal from the geomagnetic compass sensor, an input amplifier having an input coupled to an output of said chopper for receiving the signal detected by said chopper and for amplifying the detected signal;
an offset controller having an output coupled to the input of said input amplifier for applying, in response to an offset control signal, a canceling voltage to the input of said input amplifier to cancel out an offset voltage generated during an amplifying process of said input amplifier;
a low pass filter having an input coupled to an output of said input amplifier for receiving the signal amplified by said input amplifier and for filtering the amplified signal;
an automatic gain control (AGC) amplifier having an input coupled to an output of said low pass filter for receiving the signal filtered by said low pass filter, setting an amplification gain in response to a gain control signal, and amplifying the filtered signal using the set amplification gain;
an analog/digital (AD) converter having an input coupled to an output of said AGC amplifier for receiving the signal which has been amplified by said ACG amplifier and which is analog, and converting the analog signal into a digital signal; and
a digital signal processor an input coupled to an output of said AD converter for receiving the digital signal, determining a maximum value and a minimum value associated with the digital signal, determining the offset voltage and an amplitude of the analog signal based on the maximum and minimum values, and, based on the determined offset voltage and amplitude, outputting the offset control signal to said offset controller so as to cancel the offset voltage and the gain control signal to said AGC amplifier so as to control the amplitude of the analog signal within an allowable input range of the AD converter. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A signal processor for use in an electronic compass for processing signals from a geomagnetic compass sensor detecting sine or cosine wave signals induced by a drive signal according to an azimuth angle, said processor comprising:
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an analog signal processor for amplifying the signals from the geomagnetic compass sensor, canceling an offset voltage generated during an amplification process in response to an offset control signal, and controlling an amplitude of a signal in which the offset voltage is cancelled out in response to a gain control signal;
an analog/digital (AD) converter for converting analog signals from the analog signal processor into a digital signal; and
a digital signal processor for measuring a maximum value and a minimum value associated with the digital signal from the AD converter, determining the offset voltage and the amplitude based on the maximum and minimum values, and outputting, to the analog signal processor, the offset control signal to be used for canceling the determined offset voltage and the gain control signal to be used for controlling the determined amplitude so that the determined amplitude lies within an allowable input range for the AD converter;
wherein the digital signal processor;
measures the maximum value and the minimum value associated with the digital signal from the AD converter;
determines the offset voltage based on an average value of the maximum value and the minimum value;
determines the amplitude based on a difference value between the maximum value and the minimum value; and
outputs, to the analog signal processor, the offset control signal to be used for canceling the determined offset voltage and the gain control signal to be used for controlling the determined amplitude so that the amplitude lies within the allowable input range for the AD converter.
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Specification