Finding FFT from input signal

[Abuzar]

Hello,

I want to find about the FFT of the input signal from my DAQ card. I have used the Spectral Measurement block but it gives the output from 0-1 on x axis, while the frequency of the Signal is being changed.

Kindly guide me what could be wrong in this case.

Regards

[CoastalMaineBird]

I don't know about the SM block in particular, but in general, an FFT returns results in "bins" which correspond to frequencies that are related to the sampling rate, and the number of samples in the block you are analyzing.

i.e. the frequency of bin #12 is 12 * Fsamp / NPoints, while the amplitude is whatever value is in element 12 of the resulting array.

It might be that you are not providing the sample rate to the SM block, or it might be that it expects you to multiply the 0..1 by the sampling rate yourself.

[Abuzar]

Thanks alot CoastalMaineBird for you reply,

I have been succesfully managed to get the desired output, the problem was in Spectral Measurement i was creating some window to find out the the Measurement, when i made it none, i successfully got the desired output.

Thanks for your reply

Regards