Suppression of multiple narrow-band interference using real-time adaptive notch filters

The process of detection of narrow-band interference to a broad-band signal in a noisy environment using adaptive filtering techniques attributable to Kwan and Martin (1989) is further refined by modifying the gradient-search algorithm to reduce hardware complexity. The Kwan and Martin algorithm implies a geometric increase in hardware as the number of interferers increases. The improved method admits to only an arithmetic increase to achieve the similar results. Thus Kwan and Martin filters designed to handle 3 to 10 notches require 12.5% to 124% more hardware than the new filters. Simulations of the new method show it to be robust, functioning well in a variety of practical signal processing applications.