A low distortion adaptive noise cancellation structure for real time applications

This paper describes an adaptive noise cancelling structure suitable for situations where the noise reference transducer is closely spaced relative to the primary transducer. The structure is based on two LMS delay line cancellers with cross coupled feedback. This structure is shown, under certain circumstances, to cancel noise with low signal distortion when the transmission paths between primary and secondary sensors have low attenuation and the primary signal is continuous. The system is shown to have an enhanced performance when the primary signal is intermittent and a signal energy detector is used.