Periodicity using Fourier transform

2 次查看（过去 30 天）
aurc89
aurc89 2016-11-18
评论： Walter Roberson 2016-11-18
Hi everyone, I have a simple question concerning how to find the periodicity of an oscillating function using the Fourier transform. Let's suppose to have an oscillating function y=f(x) where x and y are two vectors and x is the time vector expressed in second (s). Can you suggest me a code to retrieve the frequency (or frequencies) of this function, expressed in herz (i.e. 1/s) by using the Fourier transform? Thanks a lot.
  2 个评论
Walter Roberson
Walter Roberson 2016-11-18
Are the times uniform intervals or irregular?
aurc89
aurc89 2016-11-18
In this case uniform but sometimes could be irregular in fact

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Walter Roberson
Walter Roberson 2016-11-18
If the times are uniform intervals then do peak finding on fft(y-mean(y))
See the fft example for how to calculate the frequency from bin and fs and length
  2 个评论
aurc89
aurc89 2016-11-18
So if I have a vector in second (s) how can I get the frequency of the oscillations (in 1/s) by using fft ?
Walter Roberson
Walter Roberson 2016-11-18
For x at equal time intervals,
L = length(y);
Fs = 1/(x(2)-x(1));
f = Fs*(0:(L/2))/L;
Now the first length(f) positions in fft(y-mean(y)) are associated with corresponding frequencies in f, so if you find a peak at position K then the frequency corresponding is f(K)

请先登录，再进行评论。

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