DTMF detector for detecting DTMF signals using a digital signal

Details DTMF detector for detecting DTMF signals using a digital signal DTMF detector for detecting DTMF signals using a digital signal

1996-11-19

1999-08-10

Eisenzopf, Reinhard J.

Telephonic communications

Supervisory or control line signaling

Signal receiver

379283, 379339, H04M 100, H04M 300

Patent

active

059370599

ABSTRACT:
A dual tone multi-frequency detector includes a pulse code modulation expanding unit for converting pulse code modulation data into linear data. A correlating unit constructed from a plurality of correlators correlates the linear data with a plurality of predetermined reference signals to generate a plurality of power values of a frequency band corresponding to dual tone multi-frequency signals. A total power detecting unit detects a total power value of the linear data. A low frequency maximum power detecting unit detects a maximum low frequency power value from the power values of a low frequency band generated by the correlating unit. A high frequency maximum power detecting unit detects a maximum high frequency power value from the power values of a high frequency band generated by the correlating unit. A deciding unit decides whether or not the pulse code modulation data represents a dual tone multi-frequency signal in dependence upon the total power value, the maximum low frequency power value and the maximum high frequency power value.

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