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Apparatus and method for detection ultrasonic waves propagated from within a selected distance

  • US 5,557,969 A
  • Filed: 06/27/1995
  • Issued: 09/24/1996
  • Est. Priority Date: 03/15/1994
  • Status: Expired due to Fees
First Claim
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1. An ultrasonic wave detection apparatus, comprising:

  • means for detecting ultrasonic waves and generating a first input signal responsive to said ultrasonic waves of a selected low frequency and for generating a second input signal responsive to said ultrasonic waves of a selected high frequency, wherein said selected low and high frequencies are mutually exclusive;

    means for processing said first input signal to produce a first frequency signal and a first intensity signal indicative of the frequency and the intensity, respectively, of said first input signal and for processing said second input signal to produce a second frequency signal and a second intensity signal indicative of the frequency and the intensity, respectively, of the second input signal;

    means for continuously comparing said first and second intensity signals and producing a third signal indicative of an intensity ratio of the first and second intensity signals;

    means for variably selecting a distance from the detection apparatus wherein only ultrasonic waves propagated from a source located within said selected distance will be indicated by said apparatus;

    means for generating a fourth signal indicative of an expected intensity ratio corresponding to low frequency and high frequency ultrasonic waves propagated from a source located at said selected distance from said apparatus;

    means for continuously comparing said third signal and said fourth signal, and when a predetermined relationship exists between said intensity ratio of said first and second intensity signals and said expected ratio signal, producing a fifth signal representative of the intensity of at least one of said first and second intensity signals;

    means for processing at least one of said first and second frequency signals and said fifth signal to produce an output signal; and

    notification means responsive to said output signal for producing an output indicative of at least one of said first and second input signals propagated from a source located within said selected distance of said apparatus without interference.

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