Plotting in frequency domain

[Akaash_Dragon]

I have made a LabVIEW program which is does the following: It reads some data from an LMV file, generate a graph,does some mathematical operations on the data and then writes the final mathematical answer to an excel file.

Now I want to add another additional function. I want to take in the signal(which was generated from the data) and see how much amplitude/power is there at different frequencies(which is displayed in the form of a graph).

When ever I try to create a graph it always plots it in time domain, but I want it in frequency domain. What do I do?

Also,for verification,I have tried using two function blocks 1)FFT and 2)Spectral measurements(to see if they give the same results). I have tried plotting them but somehow the graphs displayed are totally different. What is going on here?

I have also attached my VI and the images.

And thanks in advance.

[Gregory]

It's not plotting it in the time domain, it's just the "time" and "amplitude" are the default axis names for the waveform graph. It does not know about any processing you do beforehand, so you have to rename the axes manually.

Why are you running the code 100 times in a for loop if nothing changes?

Go to help >> find examples and search for "FFT". That should get you started!

[Akaash_Dragon]

Well that is for running the loop 100 times, as I had to read the signals from 100 different files. But why I am I getting different graphs if I use "spectral measurements" function (which is found is express) and "FFT" in signal processing.

I have attached the files here. Basically, what I want to find out is the amount of amplitude/magnitude in each frequency.

[Akaash_Dragon]

Also.. I have tried using the FFT(From signal processing palette)  and the Power spectrum from spectral measurements palette. I want to know how much amplitude/power is there in every frequency and want to see which frequency has the highest amplitude /frequency. All the spectrum measuring functions are giving different peak frequency values. How do I know which one is best for me?