Pulse or digital communications – Systems using alternating or pulsating current – Plural channels for transmission of a single pulse train
Patent
1996-06-20
1998-02-03
Chin, Stephen
Pulse or digital communications
Systems using alternating or pulsating current
Plural channels for transmission of a single pulse train
375261, H04K 110, H04L 2728
Patent
active
057152802
ABSTRACT:
A decoder and an encoder for extracting a subset of symbols from, or inserting a subset of symbols into, a communication channel in which M symbols are transmitted as the amplitudes of M sinusoidal carriers. The decoder recovers K symbols, S.sub.p . . . S.sub.p+K-1, from an analog signal generated by modulating M sinusoidal carriers for a frame period. Each carrier is modulated with an amplitude proportional to the value of one of M symbols, the i.sup.th carrier being modulated by symbol S.sub.i. The K symbols are a contiguous subset of the M symbols. The decoder includes a down-converter for down-converting to the modulated signal on the communication channel to generate a down-converted signal in which the carriers corresponding to S.sub.p . . . S.sub.p+K-1 occupy frequencies starting from 0. An analog-digital converter generates K time-domain samples in each frame period from the down-converted signal. These time-domain samples are converted to K frequency-domain values representing the symbols S.sub.p . . . S.sub.p+k-1 by a time-domain to frequency-domain overlapped transform. The encoder encodes K symbols, S.sub.1 . . . S.sub.K, as the amplitudes of K sinusoidal carriers, the K sinusoidal carriers comprising a contiguous block of carriers in a signal comprising M sinusoidal carriers in which each of the carriers is modulated by a signal having an amplitude determined by the value of one of the symbols for a time equal to one frame period. The encoder includes a frequency-domain to time-domain overlapped transform for generating K time-domain samples from the K symbols, the time-domain samples representing a modulated carrier comprising K sinusoidal carriers, each the carrier being modulated by a signal having an amplitude determined by the value of one of the K symbols. A digital-to-analog converter converts the K time-domain samples to an analog signal. The analog signal is then up-converted such that the sinusoidal carrier modulated by S.sub.1 has a frequency equal to the p.sup.th carrier of the M sinusoidal carriers, wherein p>0.
REFERENCES:
patent: 4802190 (1989-01-01), Schouhamer Immink
patent: 4912763 (1990-03-01), Galand et al.
patent: 5259003 (1993-11-01), Berger et al.
patent: 5497398 (1996-03-01), Tzannes et al.
patent: 5636246 (1997-06-01), Tzannes et al.
Heller Peter N.
Sandberg Stuart D.
Tzannes Michael
Aware Inc.
Chin Stephen
Ghayour Mohammad
Ward Calvin B.
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