# Zhiyun Kuang © May, 2004 Adaptive Notch Filter Application on modifying signal without changing frequency domain.

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Zhiyun Kuang © May, 2004 Adaptive Notch Filter Application on modifying signal without changing frequency domain.

Zhiyun Kuang © May, 2004 Copyright of Sound bank \$10,000 spent to record one piano sound bank. Easy to make illegal copy. Want to make characteristic on the signal without corrupting it.

Zhiyun Kuang © May, 2004 Sound properties Sound: A x Sin(2πω+Ө) A => Magnitude => Loudness ω => Frequency => Pitch, Location Ө => Phase => reverb, echo, loudness

Zhiyun Kuang © May, 2004 Time domain vs Frequency domain

Two problems: 1.Avoid canceling other frequency 2.Track original signal

Zhiyun Kuang © May, 2004 Least Mean Square algorithm

Zhiyun Kuang © May, 2004 Matlab Code x1 = C*cos(2*pi*w0*t); x2 = C*sin(2*pi*w0*t); x3 = C*cos(2*pi*w0*t+theta); x4 = C*sin(2*pi*w0*t+theta); for i = L:length(T) temp_x1 = x1(i:-1:i-L+1); temp_x2 = x2(i:-1:i-L+1); temp_x3 = x3(i:-1:i-L+1); temp_x4 = x4(i:-1:i-L+1); yk1 = sum(w1.*temp_x1); yk2 = sum(w2.*temp_x2); yk3 = sum(w1.*temp_x3); yk4 = sum(w2.*temp_x4); y(i) = yk1+yk2; yref(i) = (yk3+yk4); e = d(i)-y(i); for j=(1:L) w1(j)=w1(j)+2*u*e*temp_x1(j); w2(j)=w2(j)+2*u*e*temp_x2(j); end