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Edge detection method and apparatus for shot noise limited signals

  • US 6,129,279 A
  • Filed: 12/21/1999
  • Issued: 10/10/2000
  • Est. Priority Date: 11/01/1996
  • Status: Expired due to Term
First Claim
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1. In a barcode scanner system, a second derivative signal processor for processing an input signal from which the relative widths of the bars and spaces of a scanned barcode label are to be determined comprising:

  • first input capture means for storing the times of successive assertions of an STV signal corresponding to a light-to-dark transition;

    second input capture means for detecting a first assertion of an RTV signal corresponding to a dark-to-light transition following the successive STV signal assertions; and

    ,means for determining the relative widths of the bars and spaces in the input signal using the last STV signal assertion stored and the first RTV signal assertion.

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