2.
    发明专利
    未知

    公开(公告)号:FR2315801A1

    公开(公告)日:1977-01-21

    申请号:FR7614188

    申请日:1976-05-06

    Applicant: IBM

    Abstract: Disclosed is a method and apparatus for detecting the presence of signals, particularly touch-tone signals, of characteristic complex waveforms by comparing unknown signals with pre-specified digital formats or "masks" representative of such waveforms. The apparatus includes digital circuitry defining the masks and digital circuitry for counting the number of times during a prescribed time period there is a correlation between the digital format of the unknown signals and the masks.

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