matlab帮助文件中fft的帮助例子是这样的:
t = 0:0.001:0.6;
x = sin(2*pi*50*t)+sin(2*pi*120*t);
y = x + 2*randn(size(t));
plot(1000*t(1:50),y(1:50))
title('Signal Corrupted with Zero-Mean Random Noise')
xlabel('time (milliseconds)')
Y = fft(y,512);
Pyy = Y.* conj(Y) / 512; %%这一行中除以的512是什么意思啊?,这种算法和Pyy=abs(Y)有什么区别?
f = 1000*(0:256)/512;
plot(f,Pyy(1:257))
title('Frequency content of y')
xlabel('frequency (Hz)')
哪位大侠能指点一下吗?谢谢。