An improved weighted least-squares design for variable fractional delay FIR filters
Wu-Sheng Lu, Tian–Bo Deng · IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing · 1999
Digital filters capable of changing their frequency response characteristics are often referred to as variable digital filters (VDFs) and have been found useful in a number of digital signal processing applications. An important class of VDFs is the class of digital filters with variable fractional delay. This paper describes an enhanced weighted least-squares design for variable-fractional-delay finite-impulse response filters, which offers improved performance of the filters obtained with considerably reduced computational complexity compared to a recently proposed weighted least-squares (WLS) design method. The design enhancement is achieved by deriving a closed-form formula for evaluating the WLS objective function. The formula facilitates accurate and efficient function evaluations as compared to summing up a large number of discrete terms, which would be time consuming and inevitably introduce additional errors into the design.