FFT plot of sampled data

[ABM26]

I already have sampled data of a input signal in time domain. the signals are sampled via ADC and stored in excel file(around 16K samples). I need to feed it to FFT VI to obtain the FFT plot. I tried multiple FFT VIs but no one accept samples data directly which is stored in 1D array. Any ideas? Thanks. 

[RavensFan]

Signal Processing >> Transforms >>  FFT

That takes data stored in a 1-D array.

[ABM26]

Hi , The FFT.vi was my first line of defence. The plot I'm getting after converting ignoring the imaginary part and just taking the real part doesn't seem to give correct amplitude. 

I also need to use window (Hanning) but if I try inserting window then it give some wrong data.

Attached is my VI. If that helps.  

[DSPmchen · Accepted solution]

Hi ABM26,

Your input signal seems like a pure sine wave.  And you perform the FFT and get the amplitude.  So you get two peaks in the result.  I think this is reasonable result.   Why do you think the FFT result is wrong? 

And I notice waht you want to compute is power spectrum.  You can use Signal Processing >> Spectral Analysis >> Power Spectrum.vi directly.

[Coq_Rouge]

In the link below I have posted a FFT example. It is quite old made in Labview 6I but it does all you need. Please take a look at it.  

http://forums.ni.com/ni/board/message?board.id=170&thread.id=163587&view=by_date_ascending&page=2