High-fidelity FIR filters based on central-difference operators

A procedure is described for designing asymmetric FIR lowpass filters with high-fidelity linear-phase passbands and equirippled stopbands. Generalisations include lowpass filters with differentiating or integrating passbands, and other more general types. The method involves the truncation and modification of an infinite series of central-difference operators representing the shift operator E^τ . The use of an alternative form of frequency response expansion facilitates the effective separation of passband and stopband design procedures