Designing low-pass digital filters with fewer parameters

The finite impulse response (FIR) filters are often used in digital filter design. It has been noted that for a given design specification a FIR filter of very high order is required when the desired frequency response- is of very narrow bandwidth. In this paper, we propose a new model for linear phase low-pass narrowband digital filter design. The corresponding filter can be implemented using the classical transversal structure but with the- shift operator z^-1 replaced by an alternative operator ρ^-1. Several design examples are presented. It is shown that for a given specification, the proposed structure requires much less design parameters.