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Circuit for acoustic distance measuring

  • US 10,345,445 B2
  • Filed: 07/18/2016
  • Issued: 07/09/2019
  • Est. Priority Date: 11/02/2015
  • Status: Active Grant
First Claim
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1. An acoustic distance measuring circuit, comprising:

  • a transmitter amplifier having an output adapted to be coupled to an acoustic transducer for providing an acoustic signal thereto;

    a receiver amplifier having an input adapted to be coupled to the acoustic transducer and an output; and

    a sensing circuit having an input coupled to the output of the receiver amplifier, and an output for providing a close proximity indication flag signal, for defining a start and an end of a close proximity indication zone window, detecting an obstacle at a first time in the close proximity indication zone window if a magnitude of a first pulse received from the acoustic transducer in a proximity indication zone window at a second time is less than a first threshold but greater than a second threshold for a debounce time, and a magnitude of a second pulse received from the acoustic transducer in the proximity indication zone window at a third time is less than the second threshold but greater than a third threshold for the debounce time, wherein the third time is equal to one and one-half of a difference between the second time and the first time and providing the close proximity indication flag signal in response to detecting the obstacle in the close proximity indication zone window.

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