Electronic article surveillance system with comb filtering by polyphase decomposition and nonlinear filtering of subsequences

Abstract From the Canadian patent

A signal (120) received (124) in an electronic article surveillance system (100) is subjected to a nonlinear comb filtering function to remove interference. The nonlinear comb filtering is provided (130) by performing a polyphase decomposition of an input digital signal (128) nonlinear filtering , of the resulting subsequences and then synthesizing the nonlinear-filtered subsequences (130). A median filter may be used as the subsequence filtering function. A linear comb filtering function may be provided (130) downstream from the nonlinear comb filter to provide additional attenuation of interference.