Differences between fft, psd, pwelch etc..

122 次查看（过去 30 天）
Nicolas
Nicolas 2012-3-8
Hello!
I am trying to plot in the freq domain but I have found a lot of different ways to proceed but I cant see the difference between them and when I plot I get 4 differents plot, so basically I want to know what is the difference when you plot with fft(Y) psd(Y) or pwelch(Y,[],[],[],Fs,'twosided');

请先登录，再回答此问题。

采纳的回答

777
777 2012-3-8
fft is frequency domain plot of signal.whereas psd and pwelch are power spectrum plots ie power/frequency plot

更多回答（1 个）

Wayne King
Wayne King 2012-3-8
fft(Y) will give you a complex-valued output, which is the discrete Fourier transform of Y.
pwelch(Y, ...., 'twosided') is giving you a Welch's overlapped segment averaging power spectral density estimate where there is some averaging done to reduce the variablity of the spectral estimate. Here you are using the 'twosided' option which gives you the power estimates over an entire period from 0 to the Nyquist. That is wholly unnecessary for a real-valued signal.
psd(Y) is using an obsolete syntax. In this case your signal is divided into segments and each segment is mutiplied by a Hanning window. I think by default here there is no overlap between the segments, which is not the case in pwelch. In pwelch, the segments overlap, but you can control the amount with an input argument.

类别

在 Help Center 和 File Exchange 中查找有关 Spectral Estimation 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