Arrangement for combining data symbols in accordance with a predetermined weighting function
AssigneeBell Telephone Laboratories, Incorporated
InventorGeorge J. Kustka
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Abstract
To minimize distortion, a sequence of phase modulated signal elements (data symbols) are combined in accordance with a predetermined shaping (weighting) function by a transversal filter augmented with a baud rate control circuit. The transversal filter includes a plurality of multipliers, located at taps along a delay line, forming products between data symbols and coefficients representing segments of the predetermined weighting function. The baud rate control circuit shifts the phase of the delayed data symbols and delivers these "extended" data symbols to certain multipliers. By digitally processing segments of the weighting function and portions of an overall data symbol this invention yields to compact construction.
Claims10
In an arrangement for combining original data symbols, a circuit for shaping the amplitude of symbols in accordance witha predetermined weighting function, each data symbol being a signal modulated into one of a plurality of discrete states for a time interval, comprising:
- means responsive to the original data symbols for generating extended data symbols;
- means for generating segments of the predetermined weighting function;
- means for regulating the amplitude of said original data symbols in accordance with one of the generated segments of the predetermined weighting function;
- and
- means for regulating the amplitude of said extended data symbols in accordance with another segment of the predetermined weighting function.
A transversal filter, adapted to accept original data symbols comprising signals modulated into one of a plurality of discrete states for a time interval, including a delay line having taps for providing variously delayed signals
- characterized by:
- means for generating a sequence of tap coefficients that define segments of a predetermined weighting function;
- a multiplier jointly responsive to the original data symbol and coefficients of one segment weighting function for forming products therebetween;
- control means connected to the taps for generating an extended data symbol;
- and
- a multiplier jointly responsive to the extended data symbol and coefficients of another segment of the weighting function for forming products therebetween.
In a method for shaping original data symbols comprising signals modulated into one of a plurality of discrete states for a time interval
- the steps of:
- generating a sequence of coefficients for each of a plurality of segments that define a predetermined weighting function;
- generating extended data symbols comprising continuations in time of said original data symbols;
- multiplying each original data symbol by coefficients of one of the segments to form a product therebetween;
- and
- multiplying each extended data symbol by coefficients of another of the segments to form a product therebetween.
Dependencies are inferred from the claim text.