Telephonic communications – Supervisory or control line signaling – Signal receiver
Patent
1995-05-31
1997-04-08
Brown, Thomas W.
Telephonic communications
Supervisory or control line signaling
Signal receiver
379283, 379282, 379351, H04M 150
Patent
active
056195648
ABSTRACT:
This tone detector which is suited for dual tone multifrequency (DTMF) digit detection, separates the pairs of tones into a low frequency and high frequency group in which the other frequency group is attenuated by filtering. The amplitude of the low and high frequency groups serve as separate variable threshold reference signals. Individual tones are bandpass filtered with their corresponding outputs converted into an amplitude signal. The amplitude of the individually bandpass filtered tone signals are compared against the corresponding low or high frequency variable threshold signal for a determination of whether a tone is present. Preferably, additional validation steps are applied to the preliminary tone decisions to provide improved digit detection accuracy, especially in the presence of other signals such as speech.
REFERENCES:
patent: 5214693 (1993-05-01), Chujo
patent: 5325427 (1994-06-01), Dighe
patent: 5392348 (1995-02-01), Park et al.
patent: 5408529 (1995-04-01), Greaves
patent: 5426696 (1995-06-01), Zimbrek
patent: 5459784 (1995-10-01), Tzeng
"Algorithms for Multi-Channel DTMF Detection for the We.RTM.DSP32 Family", S.L. Gay, J. Hartung and G. L. Smith, Int'l Conference on Acoustics, Speech and Signal Processing (ICASSP), vol. 2, 23-26, May 1989, Glasgow, Scotland, pp. 1134-1137.
Digital Signal Processing, A. V. Oppenheim and R.W. Schafer, pp. 230-237, 287-289, Prentice-Hall Inc., Englewood Cliffs, NJ 1975.
"Linear Prediction Based DTMF Detection for the WE.RTM.DSP32 Digital Signal Processor Family", S.L. Gay, J. Hartung and G.L. Smith, Jun., 1989 pp. 1-19.
"Detection Of Tones While Minimizing Incorrect Identification Of Other Sounds As Tones", Serial No. 08/267,091, Filed Jun. 28, 1994 (J. W. Daugherty 2-5).
Canniff Ronald J.
Jablway Ali N.
Brown Thomas W.
Lucent Technologies - Inc.
Saint-Surin Jacques M.
Warren Charles L.
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