数字信号处理实验程序.doc

(1)N=45;
w1=boxcar(N); w2=hamming(N); w3=blackman(N);
[h,w]=freqz(w1,N);
figure(1);plot(w/pi,20*log10(abs(h))); axis([0,1,-80,10]);
grid on; xlabel('归一化频率/π'); ylabel('幅度/dB'); title('矩形窗');
figure(2);
[h,w]=freqz(w2,N);
plot(w/pi,20*log10(abs(h))); axis([0,1,-80,10]);
grid on; xlabel('归一化频率/π'); ylabel('幅度/dB'); title('汉明窗');
figure(3)
[h,w]=freqz(w3,N);
plot(w/pi,20*log10(abs(h))); axis([0,1,-150,10]);
grid on; xlabel('归一化频率/π'); ylabel('幅度/dB'); title('布莱克曼窗');
(2)N=15; w1=; w2=;
w=hanning(N); n=0:N-1;
alfa=(N-1)/2;
h=fir1(N-1,[w1 w2],w);
[h1,w3]=freqz(h,1);
figure(1)
subplot(2,1,1);plot(w3/pi,20*log10(abs(h1)));
grid on;axis([0,1,-80,10]);
xlabel('归一化频率/π');ylabel('幅度/dB');
subplot(2,1,2);plot(w3/pi,angle(h1));
grid on;axis([0,1,-4,4]);
xlabel('归一化频率/π');ylabel('角度/rad');
N=45;w=hanning(N);n=0:N-1;
alfa=(N-1)/2;
h=fir1(N-1,[w1 w2],w);
[h1,w3]=freqz(h,1);
figure(2)
subplot(2,1,1);plot(w3/pi,20*log10(abs(h1)));
grid on;axis([0,1,-80,10]);
xlabel('归一化频率/π');ylabel('幅度/dB');
subplot(2,1,2);plot(w3/pi,angle(h1));
grid on;axis([0,1,-4,4]);
xlabel('归一化频率/π');ylabel('角度/rad');
(3)N=15;w1=;w2=;
wn1=boxcar(N);wn2=blackman(N);
hn1=fir1(N-1,[w1 w2],wn1);
hn2=fir1(N-1,[w1 w2],wn2);
[h1,w3]=freqz(hn1,1);
figure(1)
plot(w3/pi,20*log10(abs(h1)));
grid on;axis([0,1,-80,10]);
xlabel('归一化频率/π');ylabel('幅度/dB');title('矩形窗,N=15');
[h1,w3]