Hi everyone,im doing a project regarding development of an adaptive
>notch filter to eliminate 50Hz noise from the
biomedical signal.im a
>newbie to matlab so im sorry if there is any term that I
>misunderstood..correct me please..here i found one `lms adaptive
>notch filter' code from the post.i tried to run it..i felt like there
>is something wrong with the spectrum of initial signal(output).i can
>see there are few sharp(spikes).i don't really know how to say
>it..why it is like that?then i've tried with giving an ecg signal
>with 50hz noise and im getting an unexpected result like the filtered
>signal is worse than the initial signal..can anybody guide me
>please..awaiting for your reply..
>
>This is the code from the post:
>(one component at 200Hz, one at 280Hz, one at 60Hz plus white noise.
>In the sequel i design an lms adaptive filter which removes the 60Hz
>component from the initial signal.`from the author')
>
>clear all
>
>Fs = 1000;
>N = 1000;
>i = [0 : N-1]';
>
>%create the initial signal
>x = sin(2*pi*200* i/Fs) + 0.66*sin(2*pi* 280*i/Fs) + 0.59*sin(2*pi*
>60*i/Fs) + 0.5^0.5*randn( N,1);
>
>%create the reference signal of the adaptive filter
>u = sin(2*pi*60* i/Fs);
>
>%adaptive filter architecture
>L = 20;
>step_size = 0.005;
>w = zeros(1,L);
>
>%run the adaptive filter
>e(L) = x(L);
>for k = L : N
>regressor = flipud(u(k-L+ 1:k));
>w = w + step_size * regressor' * e(k);
>e(k+1) = x(k) - w * regressor;
>end
>
>%compute the spectrum of the initial signal and the filtered signal
>f = [0 : Fs/N : Fs - Fs/N]';
>F = abs(fft(x));
>E = abs(fft(e));
>
>%plot
>figure;
>subplot(411) ;plot(x); title('initial signal');
>subplot(412) ;plot(e); title('initial signal after filtering');
>subplot(413) ;plot(f,F( 1:length( f)));title( 'spectrum of initial
>signal');
>subplot(414) ;plot(f,E( 1:length( f)));title( 'spectrum of initial
>signal after filtering');
>
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hello,
i wrote this code.
if you want send to my mail your ECG signal and i will test it.
Manolis C. Tsakiris
>