Telephonic communications – Subscriber line or transmission line interface – Network interface device
Patent
1992-04-16
1995-05-23
Dwyer, James L.
Telephonic communications
Subscriber line or transmission line interface
Network interface device
379406, 370 32, H04B 323
Patent
active
054188490
ABSTRACT:
A procedure and device are described for cancellation of the echo produced in telephone connections with electrical time-variant characteristics such as for example those affected by phase roll. The echo canceller obtained in accordance with the procedure which is the object of this invention produces an estimate of the echo signal by means of appropriate digital filtering of the signal originated by the far-end talker. The estimated echo is then subtracted from the actual echo. Filtering is activated by an IIR digital filter whose adaptive coefficients are updated by use of an adaptive algorithm based on decimation of the square error. The high convergence speed of said algorithm in the calculation of the coefficient correction step allows a correct estimate of the echo even in case of connections affected by phase roll.
REFERENCES:
patent: 4321686 (1982-03-01), Horna
patent: 4578543 (1986-03-01), LeBourlot et al.
patent: 4912758 (1990-03-01), Arbel
patent: 4926472 (1990-05-01), Batruni et al.
patent: 4970715 (1990-11-01), McMahan
patent: 4982428 (1991-01-01), Agazzi et al.
Digital Communications by John Proakis, published by International Student Editions, pp. 413-417.
Cannalire Giacomo
Premoli Giacomo
Ravasio Roberto
Ahmed Adel A.
Dwyer James L.
Shehata M.
Siemens Telecomunicazioni S.p.A.
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