Sample delay reduction of linear phase IIR filters by shortening section length of signals

Abstract

A technique for realizing linear phase IIR filters has been proposed by Powell and Chau. This technique contains a real-time realization of a noncausal transfer function using the following three procedures. 1) Approximate the IIR filter's impulse response to a finite length L. 2) Divide the input and output signal sequences of the IIR filter by this length L and perform a time reversal operation at each section in real time. 3) Realize a time-adjusted overlap-add for the divided section with length L by means of a two-path IIR filter. However, in 2), an L-sample delay is generated at each signal section, and in 3), an L + 1-sample delay is generated. Hence, in the entire system, a 3L + 1–sample delay is generated. In this article, the delay in 2) is discussed. It is shown that the delay in the system can be reduced by shortening the divided section length L of the signal sequence to 1 over an integer (shortened section length is also an integer). © 1999 Scripta Technica, Electron Comm Jpn Pt 3, 83(3): 1–11, 2000