Non-integer sample delay active noise canceller

Abstract From the Canadian patent

An active adaptive noise canceller (100) that inserts delays into the weight update logic of an adaptive filter to keep the filter stable. The noise and residual noise are sensed (102, 108) and the respective sensor signals are digitized at a given sample rate for processing in the adaptive filter (113). To eliminate the need for high sample rates while maintaining flexibility in the frequency regions over which the adaptive filter is stable the delay, (116) introduced into the weight update logic is a non-integer multiple of the sample period. The non-integer sample delay (118) is obtained by a sample interpolation and decimation procedure.