Fourier Transform - signal

3 次查看（过去 30 天）
viet le
viet le 2016-12-21
评论： Image Analyst 2016-12-21
Hello everyone,
I am doing relates to Fourier Transform form signal (as attached) to find the frequency of the signal. But my result is not correct (just I think because the result is so weird), I don't know where am I wrong. Plz help me fix this code.
Thank for your time
t1=0:359;
t=t1';
x = load('tremor_analysis.txt');
plot(t,x)
y = fft(x);
m = abs(y);
p = angle(y);
f = (0:length(y)-1)*359/length(y);
subplot(2,1,1)
plot(f,m)
title('Frequency')
This is my result:

请先登录，再回答此问题。

采纳的回答

Walter Roberson
Walter Roberson 2016-12-21
Remember that the first entry of the output, y(1), will store mean(x)*length(x), which is sum(x). Whenever your data is not centered around 0 you need to expect a peak at y(1).
You can either subtract off the mean(x) before doing the fft() or you can zero out y(1) before plotting.
  3 个评论
显示 1更早的评论
Image Analyst
Image Analyst 2016-12-21
Not sure what you're unclear about. He showed you one way, by subtracting the mean like he originally said. Or alternatively zeroing out y(1) like this:
y(1) = 0;
plot(y, 'b-');

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Fourier Analysis and Filtering 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by