Modem with time-invariant echo path

Details Modem with time-invariant echo path Modem with time-invariant echo path

1991-09-23

1995-01-24

Chin, Stephen

Pulse or digital communications

Repeaters

Testing

375106, H04B 138

Patent

active

053848063

ABSTRACT:
An ISDN modem. The modem includes an independent clock which controls the modem's input and output filters and two dependent clocks whose rates are functions of the independent clock and which are synchronized with external timing signals. When a dependent clock is synchronized, timing adjustment signals to other components of the modem specify the type and direction of synchronization. One of the dependent clocks and the independent clock are used to control a decimator which provides two samples of a symbol which are one independent clock cycle apart. One of the samples is a primary sample from which the symbol is interpreted and the other is a secondary sample which is used to continually train a jitter canceller. When a clock is synchronized, the secondary sample becomes the primary sample, providing the modem with a time-invariant echo path. On clock synchronization, the jitter canceller responds to the timing adjustment signals by providing adaptation information to the linear echo canceller.

REFERENCES:
patent: 3793486 (1974-02-01), Koziol
patent: 4571731 (1986-02-01), Klinkovsky et al.
patent: 4694451 (1987-09-01), Adams et al.
patent: 4792915 (1988-12-01), Adams et al.
patent: 4849997 (1989-07-01), Suzuki et al.
patent: 4924492 (1990-05-01), Gitlin et al.
patent: 5048054 (1991-09-01), Eyuboglu et al.
patent: 5054034 (1991-10-01), Hughes-Hartogs
D. Messerschmitt, "Asynchronous and Timing Jitter Insensitive Data Echo Cancellation", IEEE Trans. on Communications, vol. COM-34, No. 12, Dec. 1986.
E. Lee, Digital Communication, Sec. 9, p. 371; Sec. 15, p. 561; Sec. 18, p. 642; Sec. 20.1, p. 682, 1988.
A. Kanemasa, et al., "Compensation for the Residual Echo Increase Due to a Timing Clock Phase Jump", GLOBECOM '86, pp. 49.8.1-49.8.5. 1987.
Y. Takahashi, et al., "An ISDN Echo-Cancelling Transceiver Chip for 2B1Q Coded U-Interface", ISSCC 89/Friday, Feb. 17, 1989, 1989 IEEE Intl. Solid-State Circuits Conf., Session 17, FAM17.3, pp. 258, 259, 358 & 359 1989.
G. Sicuranza, et al. "Distributed Arithmetic Implementation of Nonlinear Echo Cancellers", 1985 IEEE, pp. 1617-1620.
G. Sicuranza, et al. "Adaptive Echo Cancellation with Nonlinear Digital Filters", 1984 IEEE, 3.10.1-3.10.4.
Cowan, et al. "Non-Linear System Modelling: Concept and Application", 1984 IEEE, 45.61-45.6.4.
O. Agazzi, et al. "Large-Scale Integration of Hybrid-Method Digital Sub-subscriber Loops", IEEE Trans. on Commun., vol. COM-30, No. 9, Sep. 1982, pp. 2095-2108.
D. Messerschmitt, "Design Issues in the ISDN U-Interface Transceiver" IEEE J. on Selected Areas in Communications, vol. SAC-4, No. 8, Nov. 1986 pp. 1281-1293.
O. Agazzi, et al. "Nonlinear Echo Cancellation of Data Signals", IEEE Trans. on Commun., vol. COM-30, No. 11, Nov. 1982 pp. 2421-2433.
AT&T Advance Data Sheet, T7264 U-Interface 2B1Q Transceiver, May 1991 pp. 1-39.

Affiliated with

Also associated with

Rating

Modem with time-invariant echo path does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Modem with time-invariant echo path, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Modem with time-invariant echo path will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1473025