# Tuner Upper Removal Demonstration

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Revision as of 13:11, 15 December 2013 by Brian.Clark (talk | contribs)

% Demonstration of LMS algorithm for noise cancellation. % Rich Kozick, Spring 1997 % Rob Frohne's modifications for Macintosh 2000. % Desired signal clear all Totaltime=1; speak('Hit a key and speak the signal.'); pause; [st, Fs] = recordsound(Totaltime, 22050, 1); s = st'; Ls = length(s); % Interference + random noise speak('Hit a key and make the noise!'); pause; [nt,Fs] = recordsound(Totaltime, 22050, 1); n = nt'; %Sign = 0.01; %Dn=20; % Delay of the noise that appears in y. %n = n(1:Ls) + Sign*randn(Ls,1); %an = [0 .01 -.5 1 -.5 .1 .01 0]; an = 4*[0 0 0 0 0 0 0 0 0 0 0 0 0 0 .5 1 .5]; bn = [1]; %sys = tf(an,bn,1/Fs); %bode(sys); %figure(1); nf = filter(an,bn,n); %nf = [nf(Dn:(Ls)); zeros(Dn-1,1)] + Sign*randn(Ls,1); y = s + nf; Sigx = 0.01; bx = [1]; % bx and ax are filtering on n to produce x ax = [1]; Dx = 1; % Delay of n that appears in x x = filter(bx, ax, n);%x = [x(Dx:(Ls)); zeros(Dx-1,1)] + Sigx*randn(Ls,1); %x = n + Sigx*randn(Ls,1); speak('Here is the noisy signal.') soundsc(y,Fs); N = 20; % Length of adaptive filter % LMS algorithm for adaptive noise cancellation h = zeros(N,1); mu = 1/(10*N*var(x)); %mu = 1.0; for k=N:Ls xk = x(k:-1:(k-N+1)); nhat(k) = h'*xk; e(k) = - y(k) + nhat(k); h = h - mu*e(k)*xk;%/(xk'*xk); end % The signal estimate is in the vector e speak('Here is the cleaned signal.'); soundsc(e,Fs);