Low noise zero crossing detection for indirect tire pressure monitoring
First Claim
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1. A magnetic speed sensor, comprising:
- a magnetoresistance sensor configured to detect a magnetic field;
an analog-to-digital converter configured to convert an analog magnetoresistance sensor signal output from the magnetoresistance sensor to a digital signal;
a digital component, including a memory, configured to;
sample the digital signal and store sensor signal samples in a buffer;
detect a zero crossing of the digital signal between two of the sensor signal samples;
continue to sample the digital signal after the zero crossing is detected and store the sensor signal samples in the buffer;
obtain a plurality of the sensor signal samples from the buffer based on a quantity of samples taken after the zero crossing that are stored in the buffer and a size of the buffer;
estimate a zero crossing time of the zero crossing based on the plurality of the sensor signal samples;
determine a speed signal based on the estimated zero crossing time; and
remove a pattern from the speed signal to determine vibration information that indicates a frequency of vibrations,the vibration information being determined based on a frequency peak, of a speed spectrum associated with the speed signal, after pattern removal,the speed spectrum, after pattern removal, having a noise floor at a level that allows the vibration information to be determined; and
an interface to;
output, to a control unit of a tire pressure monitoring system, the speed signal and the vibration information that are both generated based on the analog magnetoresistance sensor signal output from the magnetoresistance sensor,the vibration information, generated using the analog magnetoresistance sensor signal, being a basis for an indirect measurement of tire pressure by the tire pressure monitoring system.
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Abstract
A magnetic speed sensor may comprise a digital component configured to estimate a zero crossing event based on a plurality of sensor signal samples. The digital component may output, to a control unit, a speed signal that is based on the estimated zero crossing event.
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Citations
20 Claims
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1. A magnetic speed sensor, comprising:
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a magnetoresistance sensor configured to detect a magnetic field; an analog-to-digital converter configured to convert an analog magnetoresistance sensor signal output from the magnetoresistance sensor to a digital signal; a digital component, including a memory, configured to; sample the digital signal and store sensor signal samples in a buffer; detect a zero crossing of the digital signal between two of the sensor signal samples; continue to sample the digital signal after the zero crossing is detected and store the sensor signal samples in the buffer; obtain a plurality of the sensor signal samples from the buffer based on a quantity of samples taken after the zero crossing that are stored in the buffer and a size of the buffer; estimate a zero crossing time of the zero crossing based on the plurality of the sensor signal samples; determine a speed signal based on the estimated zero crossing time; and remove a pattern from the speed signal to determine vibration information that indicates a frequency of vibrations, the vibration information being determined based on a frequency peak, of a speed spectrum associated with the speed signal, after pattern removal, the speed spectrum, after pattern removal, having a noise floor at a level that allows the vibration information to be determined; and an interface to; output, to a control unit of a tire pressure monitoring system, the speed signal and the vibration information that are both generated based on the analog magnetoresistance sensor signal output from the magnetoresistance sensor, the vibration information, generated using the analog magnetoresistance sensor signal, being a basis for an indirect measurement of tire pressure by the tire pressure monitoring system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 19)
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8. A system, comprising:
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a sensor module, including a magnetoresistance sensor, an analog-to-digital converter, a digital component, a memory, and an interface, configured to; detect a magnetic field; convert an analog magnetoresistance sensor signal associated with the magnetic field to a digital signal; sample the digital signal to obtain and store sensor signal samples in a buffer; detect a zero crossing of the digital signal between two of the sensor signal samples; continue to sample the digital signal after the zero crossing is detected and store the sensor signal samples in the buffer; obtain a group of the sensor signal samples from the buffer based on a quantity of samples taken after the zero crossing that are stored in the buffer and a size of the buffer; estimate a zero crossing time based on the group of the sensor signal samples, the group of the sensor signal samples including a sensor signal sample with a value above a signal threshold, and a sensor signal sample with a value below the signal threshold; and determine a speed signal based on the estimated zero crossing time; remove a pattern from the speed signal to determine vibration information that indicates a frequency of vibrations, the vibration information being determined based on a frequency peak, of a speed spectrum associated with the speed signal, after pattern removal, the speed spectrum, after pattern removal, having a noise floor at a level that allows the vibration information to be determined; and provide, to a control unit of a tire pressure monitoring system, the speed signal and the vibration information that are both generated based on the analog magnetoresistance sensor signal, the vibration information, generated using the analog magnetoresistance sensor signal, being a basis for an indirect measurement of tire pressure by the tire pressure monitoring system. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method comprising:
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detecting, by a magnetic sensor, a magnetic field; converting, by the magnetic sensor, an analog magnetoresistance sensor signal associated with the magnetic field to a digital signal; sampling, by a digital component of the magnetic sensor, the digital signal and storing sensor signal samples in a memory, the digital component including the memory; detecting, by the digital component of the magnetic sensor, a zero crossing of the digital signal between two of the sensor signal samples; continue sampling, by the digital component of the magnetic sensor, the digital signal after the zero crossing is detected and storing the sensor signal samples in the memory; obtaining, by the digital component of the magnetic sensor, a plurality of the sensor signal samples from the memory based on a quantity of samples taken after the zero crossing that are stored in the memory and a size of the memory; identifying, by the digital component of the magnetic sensor, a zero crossing time based on the plurality of the sensor signal samples; and determining, by the digital component of the magnetic sensor, a speed signal based on the identified zero crossing time; removing, by the digital component of the magnetic sensor, a pattern from the speed signal to determine vibration information that indicates a frequency of vibrations, the vibration information being determined based on a frequency peak, of a speed spectrum associated with the speed signal, after pattern removal, the speed spectrum, after pattern removal, having a noise floor at a level that allows the vibration information to be determined; and outputting, by the digital component of the magnetic sensor and via an interface, the signal and the vibration information that are both generated based on the analog magnetoresistance sensor signal output from the magnetoresistance sensor, the digital component including the interface, and the vibration information, generated using the analog magnetoresistance sensor signal, being a basis for an indirect measurement of tire pressure by a tire pressure monitoring system. - View Dependent Claims (15, 16, 17, 18, 20)
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Specification