信号处理作业111Word文档下载推荐.docx
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plot(W/pi-1,abs(Y2),'
LineWidth'
2);
gridon;
xlabel('
\omega'
ylabel('
|W(e^j^\omega)|'
title('
矩形窗的傅里叶变换'
w1=1/3*pi;
w2=2/3*pi;
xn=cos(w1*n)+0.75*cos(w2*n);
[H,W]=freqz(xn,1,10000,'
subplot(3,2,2);
|V(e^j^\omega)|'
w1=2/14*pi;
w2=4/15*pi;
subplot(3,2,3);
w2=2/12*pi;
subplot(3,2,4);
text(0.3,26,'
\omega0=2*pi/14'
text(0.3,15,'
\omega1=2*pi/12'
w2=4/25*pi;
subplot(3,2,5);
gridon;
\omega1=2*pi/25'
运行结果:
10.4谱采样影响
n=0:
v=cos(2*pi*n/14)+0.75*cos(4*pi*n/15);
figure
(1);
subplot(3,1,1);
stem(n,v,'
.'
grid;
n'
幅值'
axis([0,63,-2,2]);
Y=fft(v);
R=real(fft(v));
subplot(3,1,2);
stem(n,R,'
k'
ylabel('
axis([0,63,-4,8]);
Re{V[k]}'
Im=imag(fft(v));
subplot(3,1,3);
stem(n,Im,'
axis([0,63,-30,30]);
Im{V[k]}'
H=abs(Y);
figure
(2);
stem(n,H,'
axis([0,63,0,32]);
DFT幅度'
)
Agle=angle(fft(v));
stem(n,Agle,'
弧度'
相位'
[H,W]=freqz(v,1,1000,'
plot(W/pi,abs(H),'
1.5);
w'
运行结果
10.5用与DFT频率一致的频率进行谱采样
v=cos(2*pi*n/16)+0.75*cos(2*pi*n/8);
subplot(2,1,1);
axis([0,63,-1,2]);
加窗的信号v[n]'
subplot(2,1,2);
加窗DFT的幅值'
plot(W/pi,abs(H));
n1=0:
w=0:
127;
v1=cos(2*pi*n1/16)+0.75*cos(2*pi*n1/8);
form=65:
128
v1(m)=0;
end
Y1=fft(v1);
H1=abs(Y1);
stem(w,H1,'
axis([0,127,0,32]);
|V[k]|'
程序结果:
10.6加Kaiser窗时对正弦信号的DFT分析
W=KAISER(64,5.48);
T=W'
;
fork=1:
64
M(k)=T(k)*v(k);
subplot(4,1,1);
stem(n,M,'
axis([0,63,-2,2]);
v[n]'
Y=fft(M);
subplot(4,1,2);
axis([0,63,0,15]);
DFT的幅值'
31;
W1=KAISER(32,5.48);
T1=W1'
32
M1(k)=T1(k)*v(k);
subplot(4,1,3);
stem(n,M1,'
axis([0,31,-1,2]);
Y1=fft(M1);
subplot(4,1,4);
stem(n,H1,'
axis([0,31,0,8]);
10.7用32点Ksise窗和补零时的DFT分析
W=KAISER(32,5.48);
form=33:
T1(m)=0;
axis([0,63,0,10]);
T2=W1'
T2(m)=0;
M2(k)=T2(k)*v(k);
Y2=fft(M2);
H2=abs(Y2);
stem(n,H2,'
axis([0,127,0,10]);
1023;
T3=W1'
1024
T3(m)=0;
M3(k)=T3(k)*v(k);
Y3=fft(M3);
H3=abs(Y3);
plot(n,H3,'
axis([0,1023,0,10]);
10.8对于频率估计的过采样和线性内插
plot(n,H1,'
-'
'
grid
axis([0,1024,0,15]);
W2=KAISER(42,5.48);
T2=W2'
form=43:
plot(n,H2,'
W3=KAISER(54,5.48);
T3=W3'
form=55:
W4=KAISER(64,5.48);
T4=W4'
T4(m)=0;
M4(k)=T4(k)*v(k);
Y4=fft(M4);
H4=abs(Y4);
plot(n,H4,'
axis([0,1024,0,18]);