New designs of linear-phase transmitter and receiver filters for digital transmission systems

New solutions to the issue of designing transmitter and receiver filters for data transmission are proposed. In this design issue, good frequency selectivity, matched filter pairs, transmit, and receive filters with a linear phase characteristic and zero intersymhol interference (ISI) are desired. As these properties cannot be-simultaneously achieved, most of the previously known algorithms relax the phase-linearity constraint. We show that relaxing the exact zero-ISI or the matched filter pair provides very efficient transmit and receive linear phase filters with high frequency selectivity. Two design algorithms are described: we propose matched filter pairs with very low ISI and nonmatched filter pairs with exact zero-ISI.