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Speed measuring apparatus

  • US 6,272,071 B1
  • Filed: 11/25/1998
  • Issued: 08/07/2001
  • Est. Priority Date: 11/26/1997
  • Status: Expired due to Fees
First Claim
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1. A speed measuring apparatus comprising:

  • transmitting means for transmitting an acoustic reference wave toward a moving-target, said acoustic reference wave being generated based on a reference signal with a predetermined frequency;

    receiving means for receiving acoustic reflection waves which are generated by said transmitted acoustic reference wave being reflected by said moving-target, converting said acoustic reflection waves to receiver signals, and outputting said receiver signals therefrom;

    signal attenuating means for selectively attenuating a signal component with the same frequency as the frequency of said reference signal, corresponding to the acoustic wave which directly enters said receiving means from said transmitting means by diffraction, and/or the acoustic waves reflected by fixed objects, in said receiver signals which are output from said receiving means and outputting signals therefrom;

    band pass filter means for selecting at least one Doppler signal component from said signals output from said signal attenuating means; and

    speed computing means for computing the speed of said moving-target relative to said speed measuring apparatus, based on said Doppler signal component selected by said band pass filter means.

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