Pulse or digital communications – Apparatus convertible to analog
Patent
1997-06-04
2000-02-22
Bocure, Tesfaldet
Pulse or digital communications
Apparatus convertible to analog
375222, 375240, H04L 2700, H04B 138
Patent
active
060288906
ABSTRACT:
A method and device for analog simultaneous voice and data transmission over an analog channel encodes at a voice signal sampling rate a sampled voice signal including spectral and pitch information. During encoding, the spectral and pitch information is extracted from the sampled voice signal to produce a residual signal, and the residual signal is converted into a sequence of residual vectors at a Baud rate. Then, a bitstream including non voice data and the extracted spectral and pitch information is produced. A modem unit, operating at Baud rate and producing an output carrier wave supplied to the analog channel, produces a sequence of symbol vectors in response to the sequence of residual vectors and the bitstream, and modulates the output carrier wave in response to the sequence of symbol vectors. A fractional sampling-rate conversion is conducted on the residual signal by shifting the voice signal sampling rate by a factor M/N, where M and N are the smallest integers that verify, or closely verify, the equality M/N=2R/F, where R is the Baud rate and F is the voice signal sampling rate. This fractional sampling-rate conversion further involves anti-aliasing filtering of the residual signal. In this manner, encoding operates at a voice signal sampling rate independent of the modem's Baud rate.
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International Telecommunication Union, ITU-T Recommendation G.729, General Aspects of Digital Transmission Systems, Coding of Speech at 8 kbit/s Using Conjugate-Structure Algebraic-Code-Excited Linear-Prediction (CS-ACELP), Mar. 1996.
International Telecommunication Union, ITU-T Recommendation V.34, Series V: Data Communication Over the Telephone Network, Interfaces and Voiceband Modems, A modem operating at data signalling rates of up to 33 600 bit/s for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circuits, Feb. 1998.
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International Telecommunication Union, CCITT Recommendation G.726, General Aspects of Digital Transmission Systems; Terminal Equipments, 40, 32, 24, 16 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM), Geneva, 1990.
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Adoul Jean-Pierre
Ardalan Sasan
Laflamme Claude
Sadri Ali S.
Salami Redwan
Bocure Tesfaldet
International Business Machines - Corporation
University de Sherbrooke
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