这个MATLAB程序运行出来以后没有图像,是什么原因呢?fs=200;deltaf=1;T=1/fs;L=1/deltaf;N=floor(fs/deltaf)+1;t=0:0.005:1;freq=0:deltaf:fs;f_t=sin(2*pi*500*t)+0.6*sin(2*pi*800*t);f_t_rectwin=f_t*rectwin(201);f_t_hann=f_t*hann(201);f_t_ha

2017-01-27

这个MATLAB程序运行出来以后没有图像,是什么原因呢?

fs=200;

deltaf=1;

T=1/fs;

L=1/deltaf;

N=floor(fs/deltaf)+1;

t=0:0.005:1;

freq=0:deltaf:fs;

f_t=sin(2*pi*500*t)+0.6*sin(2*pi*800*t);

f_t_rectwin=f_t*rectwin(201);

f_t_hann=f_t*hann(201);

f_t_hamming=f_t*hamming(201);

F_w_rectwin=T*fft(f_t_rectwin,N)+eps;

F_w_hann=T*fft(f_t_hann,N)+eps;

F_w_hamming=T*fft(f_t_hamming)+eps;

subplot(3,1,1);semilogy(freq,abs(F_w_rectwin));

title('rectwin windowing spectrum');

axis([0,200,1e-4,1]);grid on;

subplot(3,1,2);semilogy(freq,abs(F_w_hann));

title('hann windowing spectrum');

axis([0,200,1e-4,1]);grid on;

subplot(3,1,3);semilogy(freq,abs(F_w_hamming));

title('hamming windowing spectrum');

axis([0,200,1e-4,1]);grid on;

为什么下面这个运行出来以后都是直线呢?

fs=200;

deltaf=1;

T=1/fs;

L=1/deltaf;

N=floor(fs/deltaf)+1;

t=0:0.005:1;

freq=0:deltaf:fs;

f_t=sin(2*pi*500*t)+0.6*sin(2*pi*800*t);

f_t_rectwin=f_t*rectwin(201);

f_t_hann=f_t*hann(201);

f_t_hamming=f_t*hamming(201);

F_w_rectwin=T*fft(f_t_rectwin,N)+eps;

F_w_hann=T*fft(f_t_hann,N)+eps;

F_w_hamming=T*fft(f_t_hamming)+eps;

>> subplot(3,1,1);semilogy(freq,abs(F_w_rectwin));

title('rectwin windowing spectrum');

axis([0,200,1e-18,1e-14]);grid on;

subplot(3,1,2);semilogy(freq,abs(F_w_hann));

title('hann windowing spectrum');

axis([0,200,1e-16,1e-12]);grid on;

subplot(3,1,3);semilogy(freq,abs(F_w_hamming));

title('hamming windowing spectrum');

axis([0,200,1e-16,1e-12]);grid on;