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Low noise zero crossing detection for indirect tire pressure monitoring

  • US 10,254,129 B2
  • Filed: 03/23/2015
  • Issued: 04/09/2019
  • Est. Priority Date: 02/27/2015
  • Status: Active Grant
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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