公开(公告)号：GB2274372A

公开(公告)日：1994-07-20

申请号：GB9225212

申请日：1992-12-02

Applicant: IBM

Inventor： RAMM DOV ,  CHAZAN DAN

IPC: G10K11/178 ,  H04R3/02 ,  H03H17/00 ,  H03H21/00 ,  H04B1/10 ,  H04B1/12 ,  H04B3/06 ,  H04B3/20 ,  H04M1/60 ,  G10K11/16

Abstract: An adaptive noise cancellation device comprises: convolution logic 10 for convolving the signal from a reference input x with a discretised L-tap filter to form a filtered reference signal; and logic 20 for subtracting the filtered reference signal from a signal input to form an output signal; logic for generating the filter taps as a linear combination of N basis functions each having a corresponding coefficient Ck; and logic for repeatedly determining the coefficients Ck which minimise the power in the output signal z, characterised in that N is less than the number of filter taps L and the basis functions have a portion of finite width, outside of which portion the functions are substantially zero, both in the frequency and time domains, in an embodiment they are gaussians. A full-duplex speakerphone is disclosed including such a noise cancellation device.