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Apparatus for remote distance measurement

  • US 4,914,951 A
  • Filed: 12/09/1988
  • Issued: 04/10/1990
  • Est. Priority Date: 12/11/1987
  • Status: Expired due to Fees
First Claim
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1. An apparatus for remote distance measurement, especially for motor vehicles, comprising:

  • at least one electroacoustic transducer for transmitting an ultrasonic signal and for subsequently receiving an ultrasonic echo signal reflected by an object;

    an electric generator for activating the transducer at a transmission frequency;

    a receiving stage for the echo signals received by the transducer; and

    a control unit for activating the generator for a transmission time and for providing a subsequent decay time for the transducer to subsequently form a reception window for receiving reflected echo signals, the control unit further comprising means for selecting a transmission frequency at which the generator activates the transducer and for adjusting the transmission frequency for short object distances to make the decay time of the transducer oscillation less than for larger distances.

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