# What is the effect of data gaps in obtaining power spectral density using periodogram?? please help

4 visualizzazioni (ultimi 30 giorni)
Chris Martin il 24 Ott 2014
Commentato: Chris Martin il 12 Nov 2014
Dear all I have computed power spectral density using periodogram of my time series data. But there is data gaps in the time series, how periodogram takes account of the data gaps...pleas help me
##### 2 CommentiMostra NessunoNascondi Nessuno
Chris Martin il 25 Ott 2014
I dont get it properly would you explain simply......What I need to do.
Chris Martin il 12 Nov 2014
If anyone have data gaps then it is better to use lomb scargle periodogram

Accedi per commentare.

### Risposta accettata

Image Analyst il 24 Ott 2014
As you know, multiplication in the time domain is convolution in the spectral domain. Gaps in the data is like having a bunch of rects multiplied by continuous data. And the Fourier Transform of a rect is a sinc function. But you have a bunch of rects if you have a bunch of gaps. Because the Fourier Transform is a linear system F(A+B) = F(A) + F(B). So a bunch of rects is a bunch of sincs summed together in the Fourier (spectral) domain. So it would be like you have a pattern of sincs convolved with your spectrum. Now depending on the spacing and location of these gaps, the spectrum might look not much different, or it may have some ripples on it due to the convolution with the ripply sinc function. Does all that make sense or does it sound like gibberish? If gibberish, here are some tutorials to increase your knowledge and understanding:
Also look up MATLAB demos and webinars where they talk about spectral analysis and the pwelch() function (in the Signal Processing Toolbox) - they just held one a couple of weeks ago. http://www.mathworks.com/searchresults/?q=spectral&q1=spectral&q2=&q3=&notq=&c[]=webinars
##### 0 CommentiMostra -2 commenti meno recentiNascondi -2 commenti meno recenti

Accedi per commentare.

### Categorie

Scopri di più su Spectral Estimation in Help Center e File Exchange

### Community Treasure Hunt

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

Start Hunting!

Translated by