디지털신호처리과목 DSP필터설계

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본문내용

1. myfir.m 과 myiir.m의 Code

< myfir.m >

Ns = 2; % [sec]
fm = 200; % frequency of message signal
fn = 1000; % frequency of noise signal
Fs = 8000; % sampling frequency
N = Fs * Ns; % number of samples

n = [0:N-1];
x1 = cos(2*pi*(fm/Fs)*n); % message signal generation
x2 = cos(2*pi*(fn/Fs)*n); % noise signal generation
x = x1 + x2;

M = 20;
fc = 600;
wc = fc/(Fs/2);
B = fir1(M,wc);

[H, w] = freqz(B,1);
mag = abs(H);
db = 20*log10((mag+eps)/max(mag));

subplot(3,1,1);
stem([0:20],abs(B)); grid;
ylim([-0.2 0.2]);
subplot(3,1,2);
plot(w/pi,mag); grid;
subplot(3,1,3);
plot(w/pi,db); grid;

y = filter(B,1,x);

L = Fs/fm*10;
Xk = fftshift(fft(x, L));
Yk = fftshift(fft(y, L));

figure
subplot(2,2,1); plot(x);
xlim([0 400]); ylim([-2 2]);
subplot(2,2,2); plot(abs(Xk));
xlim([0 400]); ylim([0 250]);
subplot(2,2,3); plot(y);
xlim([0 400]); ylim([-2 2]);
subplot(2,2,4); plot(abs(Yk));
xlim([0 400]); ylim([0 200]);

soundsc(x,Fs);
sprintf('Press Any Key!')
pause
soundsc(y,Fs);

참고 자료

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