초록 ▼

A variable-passband, variable-phase digital filter in which Q digital samples of a signal are entered through (Q-1) delay lines, to be delayed into q two-bit adjacent doublets. Weighting tables in read only memories are addressed by each doublet. Each weighting table includes the results of linear c

A variable-passband, variable-phase digital filter in which Q digital samples of a signal are entered through (Q-1) delay lines, to be delayed into q two-bit adjacent doublets. Weighting tables in read only memories are addressed by each doublet. Each weighting table includes the results of linear combinations of the weights of doublets composed of bits of the same order multiplied by multiplier coefficients which are smaller than unity. Each integral portion of a result found in a table is applied at the same time as the fractional portions of the other results provided by the other tables to the addressing inputs of a programmed memory containing binary words. Binary words are addressed in the prorammed memory by the integral and fractional portions of the results found in the weighting tables. Each binary word has a value equal to the linear combination of the corresponding values of the samples of the signal by the multiplier coefficients.

대표청구항 ▼

A variable-passband variable-phase digital filter of the type in which Q digital samples of a signal to be filtered, which are coded on 2×q bits, are applied successively to (Q-1) delay lines connected in series, and in which the values of the delayed samples are weighted by Q multiplier coefficient

A variable-passband variable-phase digital filter of the type in which Q digital samples of a signal to be filtered, which are coded on 2×q bits, are applied successively to (Q-1) delay lines connected in series, and in which the values of the delayed samples are weighted by Q multiplier coefficients which are smaller than unity and are collected at outputs of each delay line, and are combined, to form a series of samples representing the filtered digital signal, comprising: means for subdividing said sample to be filtered and each delayed sample into q adjacent, weighted two-bit doublets; first storage means, coupled to said subdividing means to be addressed by each doublet, for storing weighting tables, each said weighting table results of linear combinations of weights of doublets composed of bits of the same rank multiplied by said multiplier coefficients, and producing at the same time an integral portion of said results in said weighting tables and fractional portions thereof; second storage means having a plurality of addressing inputs receiving at the same time the integral and fractional portions thereof, and for ensuring that each binary number addressed in the second storage means by said integral and fractional portions of the results from said first storage means as a function of the values of the Q samples of the signal to be fiItered, has a value equal to a linear combination of corresponding values of the Q samples of the signal by the Q multiplier coefficients.