| 摘要 |
A selective bar code reader distinguishes code data from other data obtained from a carrier before reading the data. The selective bar code reader comprises a scanner for generating electrical signals having a first portion representing the code and a second portion representing other regions on the carrier, a processor for generating an electrical waveform having a first portion corresponding to the first portion of the electrical signals and having a fundamental frequency corresponding to the spacing between the bar code elements and a second portion corresponding to the second portion of the electrical signals and not having a fundamental frequency corresponding to the spacing between the elements of the bar code. The electrical waveform is passed through a band pass filter centered at the fundamental frequency to attentuate the second portion of the electrical waveform and thereby to identify the first portion of the electrical waveform and the bar code data.
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