Telephonic communications – Supervisory or control line signaling – Signal receiver
Patent
1993-09-10
1995-02-14
Dwyer, James L.
Telephonic communications
Supervisory or control line signaling
Signal receiver
379406, 379410, 379402, H04M 908
Patent
active
053902440
ABSTRACT:
An apparatus and method for detecting the presence of ringer signals in a telephone which samples the incoming telephone signals within a prescribed time interval, windows the signals, and computes a set of auto-correlation coefficients. These coefficients are normalized, and their absolute values are calculated and summed and compared with an empirically-derived threshold. If the coefficient sum exceeds the threshold, a high degree of correlation within incoming signals is indicated, distinguishing the incoming signal as containing ringer signal constituents.
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Moving Discrete Fourier Transform B. G. Sherlock, D. M. Monro IEE Aug. 4, 1992 pp. 279-282.
Gaut Eric K.
Hinman Brian L.
Huang Shan-Shan
Dwyer James L.
Ferrell John S.
Polycom, Inc.
Saint-Surin Jacques M.
Sloan Leif R.
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