Adaptive IIR bandpass decimation filter for single sinusoid detection

Abstract

This paper proposes an adaptive second‐order IIR bandpass decimation filter for detecting a single sinusoid with an unknown frequency embedded in noise. The purpose is to realize a filter with high Q (selectivity) and less output amplitude fluctuation after convergence. As the first step, the adaptive second‐order IIR bandpass filter with the variable center frequency is outlined. Then, we present a new method that derives the decimation filter function with a small amount of computation. The filter is derived from the above filter with the denominator coefficient made variable, and with the polynomial of z−M as the denominator, where M (integer) is the decimation ratio. A method is shown to design the adaptive signal generator and the coefficient update circuit for a single sinusoid detection adaptive filter based on the proposed method. Lastly, the convergence and the output error characteristics of the proposed adaptive decimation filter are examined by a computer simulation example. © 2000 Scripta Technica, Electron Comm Jpn Pt 3, 83(7): 91–101, 2000