Pulse or digital communications – Receivers
Patent
1997-06-12
1999-11-30
Chin, Stephen
Pulse or digital communications
Receivers
379 31, 379 9326, 379 9327, 379283, 379339, 379386, H03K 900, H04L 2706, H04L 2714, H04L 2722
Patent
active
059955570
ABSTRACT:
To detect a dual tone pair signal in a telephone communication system, the signal is sampled at the Nyquist frequency. The sampled signal is filtered to determine the top three tone frequency power results. The input signal is then resampled at one-half of the Nyquist frequency. The resampled signal is filtered to determine signal power in the row and column frequency bands. The top three power results from tone filtering and aliasing row and column band pass filter power results are checked for lack of excess power to reject false digits.
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Chin Stephen
Maddox Michael W.
Nortel Networks Corporation
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