WLS quasi-equiripple design of variable fractional delay FIR filters

To design an FIR filter, the Weighted Least Squares (WLS) method is a well-known technique. And it has already been extended to design a variable fractional delay FIR filter. It is reported that the efficiency is better than the method based on Lagrange interpolation. In this paper, the WLS method cooperated with an iterative procedure for obtaining a suitable frequency response weighting function, a quasi-equiripple variable fractional delay filter can be achieved. Simulation results show that after no more than eight iterations we can get rather satisfied results. Besides, the proposed design is superior to the plain WLS (weighting function is constant and fixed) design in peak absolute error by 6.7 dB.