Inverse Fourier Tansform

[samir34]

I am connected to a Spectrum Analyzer via GPIB using LabVIEW 7.1. I am able to control the anaylzer and gather the data(plot and table) in the frequecy domain. However, I need to convert the data taken in the frequency domain and convert it to the time domain.  I am trying to use the real IFFT.vi, but not not quiet sure if I'm using it correctly.  I have a 2D- array(frequency and Amplitude) and the VI only has a 1-D input.  The final result I need is to have a table and plot of the data in the time Domain.  Any help would be greatly appreciated. thanks

[altenbach]

You only need to transform the 1D array of amplitudes. You need to know the frequencies to get deltaF from which you will be able to calculate the delta time in the transform, but that is just a scaling task. You also need to know how the frequency domain data is arranged, because there are a few flavors (e.g. DC centered, Nyquist centered).

Please attach your VI with some representative data contained in a diagram constant and I'll have a look.

Don't confuse array dimensionality. A true 2D array has three dimensions: (row index, column index, value), most likely you have a 2D array with e.g. two colums, one for the amplitude and one for the frequency, so it is more like a compact representation of 2 1D arrays.

[samir34]

here is my program.

[rpursley8]

You can't really convert spectrum analyzer data to the time domain because you lack the phase information.  To do what you want you have to have a reference signal to compare your results to.  Then you can determine the change in amplitude and phase that has occurred at each frequency.

A network analyzer outputs the information you need to convert to the time domain

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[samir34]

oh, here is my Data collected.

[samir34]

Thanks.