time series to power spectra

[uclabme]

Hello, Experts,

I have data of voltage output variance over long period of time. And I'd like to do a power spectral graph(voltage amplitude over frequency). Is there anyway I can extract that information without running the experiment again? for example use FFT first then...? or must I use a spectrum analyzer and run the experiment again?

if I can indeed use labview...what function do i use?

thank you for clarifying.

ck

[devchander]

You could always save the Voltage data/ Analysis results using suitable 'File I/O' functions in labview.

Save the acquired voltage, read it offline using these file functions  and perform spectral analysis on it.

Similiarly, you can also save the results of spectral analysis.

further doubts??, do get back

regards

Dev

Message Edited by devchander on 02-27-2006 05:56 AM

[Peter42]

I have recorded a time series (a modulated wave train).  I would like to determine the low-frequency components that modulate the otherwise very stable square wave signal.  Is there an example available for inputing the wave train (voltage) and the sampling frequency for getting the dominant frequency of the wave train and the low-freqency component(s) the moduate the wave train via specral analysis?  Your advice please.

Peter Liiu 

[mikeporter]

To start do a search in the examples that came with LV for FFT. This will show you a good cross-section of what LV has to offer in terms of analysis capabilities. The thing to remember is that you can perform this analysis on data directly from a device or post-process data that you read from a datafile. After going through the examples if you have specific questions, we'll be able to give more specific answers...

Mike...