Implementation of IIR ADF for narrow band noise elimination by using of DSP

Abstract

An Adaptive Digital Filter (ADF), which has palarel connected 2nd order IIR filters, for narrow band noise elimination is proposed already. The proposed adaptation algorithm, however, does not take account of delay caused by anti-alias Low-Pass Filter (LPF) and Analogue to Digital (A/D), and Digital to Analogue (D/A) converter. So, in real applications, the ADF implemented with Digital Signal Procceser (DSP) shows poor capability of eliminating narrow band noise. In this paper, we propose a method to compensate phase of output signal from ADF. The compensation is accomplished with lst order FIR filter inserted in the output line of the ADF. We also show how to set the coefficient values of the FIR filter. And, we scrutinize ability to eliminate noise and computational cost through practical implementation of the ADF and the proposed phase compensation filter.