Mode selective quadrature amplitude modulation communication sys

Details Mode selective quadrature amplitude modulation communication sys Mode selective quadrature amplitude modulation communication sys

1992-03-24

1994-11-08

Chin, Stephen

Pulse or digital communications

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Testing

375106, 375 94, 329304, 332103, 371 46, H04L 512, H04L 2302

Patent

active

053634080

ABSTRACT:
A quadrature amplitude modulation (QAM) communication system is provided in which data can be communicated in any one of a plurality of QAM modes, such as 16-QAM, 32-QAM, and 64-QAM. A receiver detects the particular QAM mode transmitted on a trial and error basis, by attempting to decode the received data using different QAM modes until a synchronization condition is detected. The synchronization condition can require that a plurality of different synchronization tests be met. In a specific embodiment, a first synchronization test is met when a renormalization rate of a trellis decoder is below a threshold value. A second synchronization test is met when a first synchronization word is detected in the received data. A third and final synchronization test is met when a second synchronization word is detected in the received data. In order to reduce the cost of the receiver, most of the QAM mode dependent components are implemented using look-up tables stored in PROMs.

REFERENCES:
patent: 4495619 (1985-01-01), Acampora
patent: 4501020 (1985-02-01), Wakeman
patent: 4597107 (1986-06-01), Ready et al.
patent: 4677625 (1987-06-01), Betts et al.
patent: 4845707 (1989-07-01), Isaacson et al.
patent: 4937844 (1990-06-01), Kao
patent: 5117427 (1992-05-01), Miyake et al.
Viterbi, et al., "A Pragmatic Approach to Trellis-Coded Modulation," IEEE Communications Magazine, Jul.1989, pp. 11-19.

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