Pulse or digital communications – Systems using alternating or pulsating current – Plural channels for transmission of a single pulse train
Patent
1997-07-11
1999-06-29
Pham, Chi H.
Pulse or digital communications
Systems using alternating or pulsating current
Plural channels for transmission of a single pulse train
375341, 371 43, H04L 2728, H04L 512
Patent
active
059178590
ABSTRACT:
An improved Viterbi detector for use in a partial-response maximum-likelihood (PRML) channel. The present invention reduces the amount of hardware necessary in the conventional digital implementation, as well as increasing the speed of the system, by utilizing analog circuits. Whereas prior art analog implementations use more complex hardware and less efficient algorithms, the present invention utilizes easily realizable circuitry to perform a more efficient algorithm. A sampled data Viterbi detector compares a sampled analog input signal with two threshold signals. The binary outputs of the comparing means are then provided to a survival sequence register, as well as being used to formulate new threshold signals for the subsequent input sample. The hardware implements Ferguson's method for calculating sequence metrics by representing the accumulated metric difference as two threshold signals. Probability based decisions are then performed in analog comparators. Because Ferguson's method only requires formulation of the difference between metrics rather than formulation of the true metrics themselves, the successive threshold signals that represent this difference can be generated using multi-input track and hold circuits and a voltage summing means.
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Pan Tzu-Wang
Yamasaki Richard G.
Brady III Wade James
Donaldson Richard L.
Pham Chi H.
Silicon Systems Inc.
Swayze, Jr. W. Daniel
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