Hi, I am using NI GPIB to interface Tektronix TDS 3012B to PC. I can communicate between the scope and the PC. I used Channel 1 of the scope to display the sinusoidal signals from the function generator GFG-8250A. What ever signal I adjust [amplitude and frequnecy] from the generator is displayed on the scope. i.e. there is no problem regarding the time domain signals. Then I used I tried, FFT power spectrum VI and, spectral measurement VI and FF spectral (Mag-Phase) VI and the corresponding example VIs, in order to perform the spectral analysis of the applied signals. But I couldnt get the right frequency in the spectral analysis, also the frequncy in the x-axis seems to be not correct (always ranging from 0 to 0.5 Hz even if I adjust the frequency to M Hz range). I tried several times to change the configuration of the VIs used but no response. May be the problem due the selection of the sampling frequency which I do not Know how to do it. Note: I tried exercise 6.1 Fast Fourier Transform in the Data acquisition and signal processing course manual [using NI DAQ module] both ONE-side FFT and TWO-side FFT] can be seen and it work nicely. Would you please give some hints to solve this problem. Thanks a lot

Instrument Control (GPIB, Serial, VISA, IVI)

FFT of a signal

Author

Hi TonP and Dennis Knight from NI

I have made several experiments following the advice offered and I got the expected results.

Thanks a lot for your kind advice and help

regards

maleeho

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Instrument Control (GPIB, Serial, VISA, IVI)

FFT of a signal

Re: FFT of a signal