On the simultaneous amplitude and phase approximations of wave digital lattice filters

The paper presents new solution for the problem of simultaneously approximating the amplitude and phase functions of wave digital lattice filters. The approximation is relying on translating the amplitude and phase specifications into corresponding specifications for the difference and sum phase functions of the two branch polynomials. As a consequence, the phase specifications for each of the two branch polynomials is determined. Accordingly, these two polynomials are generated such that the amplitude and phase functions are approximated alternatively. This means that while one of these functions is approximated, the other is fixed. By iterating this alternative process, the two functions converge to their optimal response. Copyright (C) 2003 John Wiley Sons, Ltd.