Telephonic communications – Supervisory or control line signaling – Signalling integrity protection
Patent
1992-08-27
1994-06-14
Dwyer, James L.
Telephonic communications
Supervisory or control line signaling
Signalling integrity protection
379386, 379282, H04M 100
Patent
active
053217454
ABSTRACT:
A process for determining the presence of either speech or one of a plurality of expected single-frequency signals on a line includes the steps of measuring the total signal energy on the line; measuring the signal energy present in each one of a plurality of selected separate frequency bands and identifying the two frequency bands having the highest signal energies; determining whether the highest signal energy exceeds a first selected threshold value; determining whether the highest signal energy exceeds the second highest signal energy by greater than a second selected threshold value; determining the amount of out-of-band signal energy; and determining whether the highest signal energy exceeds the out-of-band signal energy by greater than a third selected threshold value. A process for determining the presence of two of a plurality of expected a single-frequency signals on a line includes the steps of measuring the total signal energy on the line; measuring the signal energy present in each one of a plurality of selected separate frequency bands and identifying the three frequency bands having the highest signal energies; determining whether the two highest signal energies exceed a first selected threshold value; determining whether the second-highest energy exceeds the third-highest energy by a second selected threshold value; determining the amount of out-of-band signal energy and determining whether the sum of the two highest signal energies exceeds the out-of-band energy by a third selected threshold value; and determining whether the ratio of the two highest signal energy values exceeds a fourth selected threshold value.
A method for identifying expected call progression signals on a telephone line, comprises the steps of (1) sensing the presence of energy on the line and determining if the energy comprises speech; (2) identifying the frequency content and duration of the energy; 3) comparing the frequency content of the energy with stored information comprising the frequency content of expected signals and identifying the energy as one of the expected call progression signals if a match is found; (4) sensing the presence of silence on the line if no match is found; (5) identifying the duration of the silence; (6) repeating steps (1) through (5) for a predetermined number of times; and then (7) comparing the frequency content of the energy, the duration of the energy, and the duration of the silence with stored information comprising the frequency content of energy, the duration of energy, and the duration of silence for a plurality of expected call progression signals and identifying the energy as one of the expected call progression signals if a match is found.
REFERENCES:
patent: 4045620 (1977-08-01), Westbrook
patent: 4091243 (1978-05-01), Mizrahi et al.
patent: 4460808 (1984-07-01), Battista et al.
patent: 4477698 (1984-10-01), Szlam et al.
patent: 4677665 (1987-06-01), Walker
patent: 4689760 (1987-08-01), Lee et al.
patent: 4979214 (1990-12-01), Hamilton
Alan V. Oppenheim and Ronald W. Schafer, Digital Signal Processing, Prentice-Hall, Inc., pp. 287-289, 1975.
Dialogic, "Customizing D/41 Call Analysis," Application Note AN002, pp. 1-101, 1988, 1989.
L. R. Rabiner and R. W. Schafer, Digital Processing of Speech Signals, Prentice-Hall, Inc., 1978, LC Call No. TK7882.S65 R3, ISSN #0132136031.
R. E. Blahut, Fast Algorithms for Digital Signal Processing, Addison Wesley, 1987, LC Call No. TK5102.5.B535 1985, ISBN #0201101556.
Baumann Clifford N.
Drory Eatamar
Machuta Robert J.
Perry Ron A.
Dwyer James L.
Smith Creighton
VMX, Inc.
LandOfFree
Adaptive efficient single/dual tone decoder apparatus and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adaptive efficient single/dual tone decoder apparatus and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adaptive efficient single/dual tone decoder apparatus and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1255211