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Patterned transducer apparatus for correcting spurious signals in said devices

  • US 5,023,605 A
  • Filed: 01/19/1990
  • Issued: 06/11/1991
  • Est. Priority Date: 11/25/1988
  • Status: Expired due to Fees
First Claim
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1. A security device for a motor vehicle that provides a coded surface acoustical wave which is converted to an electrical signal for comparison with a preset code, said security device comprising:

  • a substrate having means defining an acoustical wave path; and

    a pattern of transducers disposed upon said substrate for providing said coded surface acoustical wave, including a plurality of spaced-apart tap transducers disposed along said acoustical wave path and operatively connected to a main transducer, at least one of said tap transducers is disposed upon said substrate to produce a signal pulse of opposite phase but approximately equal amplitude with respect to a crosstalk signal pulse in order to cancel same, and said pattern of transducers being further characterized by being operative to propagate acoustical waves in a relative direction towards and away from said main transducer to provide a bidirectional wave propagation with respect to said substrate.

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