Factorable FIR Nyquist filters with least stopband energy under sidelobe level constraints

Spectrally factorable Nyquist filters are used in data communications to avoid intersymbol interference. An approach is developed for obtaining a Nyquist filter that is factorable having the smallest stopband energy for a given sidelobe level. The resulting constrained minimization problem is solved efficiently and reliably using the Goldfarb-Idnani (1983) algorithm. Some examples are presented comparing the present method with a previous approach from the literature.