DESIGN OF FIR NYQUIST FILTERS USING THE REMEZ EXCHANGE ALGORITHM

In this paper, we propose a method of designing FIR Nyquist filters wi th zero intersymbol interference by using the Remez exchange algorithm directly First, we present some magnitude properties of FIR Nyquist f ilters with zero intersymbol interference. It is known from the time-d omain condition of zero intersymbol interference that the magnitude re sponse of Nyquist filters in the passband is mainly dependent on the s topband magnitude. Therefore, the design problem of Nyquist filters be comes optimization of the magnitude response in the stopband. By using the Remez exchange algorithm in the stopband directly, we formulate t he design problem in the form of a linear problem. The filter coeffici ents can be computed by simply solving the linear equations, and the o ptimal coefficients with equiripple stopband response are easily obtai ned after a few iterations. The proposed procedure is computationally more efficient than the existing procedures. Finally, we extend the pr oposed procedure to the design of matched Nyquist filter pairs, multis tage Nyquist filters, and so on, Some design examples are presented to demonstrate the effectiveness of the proposed procedure. (C) 1997 Scr ipta Technica, Inc.