Fast fourier transform scaling

[jerryjni]

I'm a newcomer to labview and I'm having some trouble with the FFT spectrum.  I'm feeding a 1HZ 1vpp sine wave from the signal generator into the DAQ.  On the power spectrum graph i see the FFT performed on the sine wave, however no matter how I change the x scaling, the frequency on the X axis of the graph does not correspond to the frequency that I am inputting in terms of where the spike should be.  Is there a way I can alleviate this? Thanks

[tbd]

Hi jerry,

      I used the FFT recently and found if I set my chart's X-Scale Scaling-factor\Multiplier properly, then the Power-spectrum results were plotted at expected frequency.

The proper setting for Multiplier was 1/(DAQ_Period(sec)).  So if your sine-wave represents 4 seconds of data, then set multiplier to 0.25.

I'm by no means an FFT expert - just an idea!

Cheers!