Pract4

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Daniel Castillo Gamez 
Practica
F = [100 200 300 400] * 1e3;
Fc = 15e3;
Fp = Fc - Fc * 0.2;
Fs = Fc + Fc * 0.2;
fmax = max(F);
fs = 20 * fmax;
Wp = Fp / (fs/2);
Ws = Fs / (fs/2);
% Design a digital filter
d_equiripple = designfilt('lowpassfir', ...
 'FilterOrder',50,'PassbandFrequency',120000, ...
 'StopbandFrequency',180000,'SampleRate',fs);
% Visualize magnitude and phase responses
freqz(d_equiripple.Coefficients,1,[],fs)
% Design a digital filter
d_kaiser = designfilt('lowpassfir', ...
 'PassbandFrequency',120000,'StopbandFrequency',180000, ...
 'PassbandRipple',1,'StopbandAttenuation',60, ...
 'SampleRate',fs,'DesignMethod','kaiserwin');
% Visualize magnitude and phase responses
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freqz(d_kaiser.Coefficients,1,[],fs)
% Get filter information
info(d_kaiser)
ans = 20×32 char array
 'FIR Digital Filter (real) '
 '------------------------- '
 'Filter Length : 494 '
 'Stable : Yes '
 'Linear Phase : Yes (Type 2) '
 ' '
 'Design Method Information '
 'Design Algorithm : Kaiser window'
 ' '
 'Design Options '
 'Minimum Order : any '
 'Scale Passband : true '
 ' '
 'Design Specifications '
 'Sample Rate : 8 MHz '
 'Response : Lowpass '
 'Stopband Atten. : 60 dB '
 'Passband Edge : 120 kHz '
 'Passband Ripple : 1 dB '
 'Stopband Edge : 180 kHz '
t = 0:1/fs:100/fmax;
senal = 2 * sin(2*pi*F(1)*t) + 2 * sin(2*pi*F(2)*t) + 2 * sin(2*pi*F(3)*t) + 
2 * sin(2*pi*F(4)*t);
senal_resultante = 2 * sin(2*pi*F(1)*t);
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senal_filtrada_equiripple = filter(d_equiripple, senal);
senal_filtrada_kaiser = filter(d_kaiser, senal);
figure;
subplot(3,1,1);
plot(t, senal);
title('señal normal');
subplot(3,1,2);
plot(t, senal_filtrada_equiripple, '+k', t, senal_resultante, 'r');
title('señal filtrada equiripple y señal filtrada esperada');
subplot(3,1,3);
plot(t, senal_filtrada_kaiser, '+k', t, senal_resultante, 'g')
title('señal filtrada de kaiser y señal filtrada esperada');
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