how can i implement fftshift in LabVIEW

[jamison.suade]

How do i implement fftshift in my program.?

So basically, I have a double-sided fft, and i want this to be shifted in order to have zero frequencies, just like the matlab image below.

[GerdW]

Hi gijude,

split the fft result array in two halfs and swap their order. Then adapt the x axis to reflect the real frequencies using the offset and gain properties…

[Bob_Y.]

Yeah, what Gerd said is right.

But I think about it like this: From 0 to 250 (max frequency based on the sample time), the graph is correct. From there on, you need to subtract 500 (2*Freq(max)). Coding this should be pretty straightforward.

[jamison.suade]

Sir GerdW, 

Where can i find the split? And also whre is the reflect located?

[jamison.suade]

Sir GerdW, 

Where can i find the split? And also whre is the reflect located?

[natasftw]

Think of what it would take to split an array.

You need to find out how many elements it has.

Then, you want to keep an array that is a subset of the original array with half the points.

Then, you want a copy that's reversed.

Finally, you want a concatenated array built from the two smaller arrays.

Play around in the functions palette to see if you can find anything that will handle that for you.  Certainly don't hardcode a shift of 500.  That works for this solution but is useless in the general sense.

[jamison.suade]

This is my VI, and I want to implment fftshift on this one

[natasftw]

Which of those steps did you try?

[jamison.suade]

I tried using the split array

[GerdW]

Hi gijude,

when you have problems with those (VERY) basic array operations you should take all those FREE online courses offered by NI on their website…

Try this: