time shift

[gareth1983]

Hi all,

hope someone can help me with this problem, I'm supposed to perform a time shift for my signal however it does not work..

I have an original signal which I need to do a time shift using DFT (Discrete Fourier Transform)

I had used 1D fourier interpolation.vi  to do DFT but 'm not too sure whether this is the right .VI to use. If it is, is there any better .VIs which I can use?

Can someone please help me with this problem, having a time shift by using DFT.

Thanks a lot in advance!!

[altenbach]

Your code makes very little absolutely no sense.

• You are doing a Fourier interpolation with n=1, which gives you the input back as output, so why even do it?
• Your use of Y[i]=X[i-n] is truly ridiculous. have you even looked at the online helf for this function??? You wire a waveform to the "shift:n" input, which actually expects a single integer.

Can you explain what you are trying to do? Is this homework for school?

[gareth1983]

Hi altenbach,

Ya you are right, it's for my school work. My lecturer wouldn't want to give more guidelines for me that's why I'm looking at this forum for some help.

Firstly, I would like to apply the DFT to the input signal, as I had mentioned earlier and then perform a time shift.

At first I had used fourier transform.vi to perform DFT but the output signal looks pretty weird.

By right when I were to apply DFT to a signal, I should get a output signal as the amplitude domain right?

[gareth1983]

Hi all,

May I know how can I do a simple discrete time fourier transform first? Can amend the program which I had sent out earlier for me to compare at least I know what I had done wrong. I've tried writing a formula manually, used the Interpolate 1D fourier and FFT.vi(s) but it just seems that I'm wrong everytime.

What I understand is, by applying fourier transform signal, I should be getting a frequency response graph. I did get a frequency response graph earlier, however when I calculate it with respect to the values I'd set to perform the operation, it's wrong again.

Please find attached my revised program and your superb advises, a million thank you in advance.