Fast training echo canceller

Details Fast training echo canceller Fast training echo canceller

1989-04-05

1991-01-22

Ng, Jin F.

Multiplex communications

Wide area network

Packet switching

379410, H04J 300

Patent

active

049875698

ABSTRACT:
An echo cancellation modem having a fast training echo canceller in which the echo cancellation coefficients are computed by taking correlations between a complex, periodic training signal sequence and a real component of the corresponding echo signal. The modem includes a receiver circuit for detecting a signal on a channel possibly including an echo; an echo canceller for estimating the real component of the echo signal; training circuitry for applying the complex training sequence to the channel and for taking correlations between the training sequence and the real component of the corresponding echo signal. The modem also includes a computational element for computing the period of the periodic sequence, generating the complex periodic train sequence in real time and for computing a phase roll frequency based upon the computed echo cancellation coefficients.

REFERENCES:
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patent: 4621173 (1986-11-01), Guidoux
patent: 4682358 (1987-07-01), Werner
patent: 4813073 (1989-03-01), Ling
J. Cioffi et al., "An Efficient RLS Data-Driven Echo Canceller for Fast Initialization of Full-Duplex Data Transmission", IEEE Transactions on Communications, vol. COMM-33, No. 7, Jul. 1986, pp. 601-611.
J. Cioffi, "A Fast Echo Canceller Initialization Method for the CCITT V32 Modem", GLOBECOM87, pp. 1950-1954.
T. Kamitake, "Fast Start-Up of an Echo Canceller in a 2-Wire Full-Duplex Modem", Links for the Future, 1984, pp. 360-364.
V. Kanchan et al., "Measurement of Echo Path Response", IEEE Transactions on Acoustics, Speech, and Signal Processings, vol. 36, No. 7, Jul. 1988, pp. 1008-1010.
M. Honig, "Echo Cancellation of Voiceband Data Signals Using Recursive Least Squares and Stochastic Gradient Algorithims", IEEE Transactions on Communications, vol. COM-33, No. 1, Jan. 1985, pp. 65-73.

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