difference of FFT.vi in FFT Spectrum (Mag-Phase).vi

[sean1985]

Hi!

I have 1 signal goes through 2 vis i got 2 differenct answer. FFT spectrum(Mag-Phase) measures the magnitude and phase.. so does the FFT.vi of the magnitude. However FFT spectrum brings me a postive magnitude whereas FFT brings me some negative magnitude in some of the freq domians? Whats the difference lies at? The FFT sample size???

I dunno.

Plase help

[rpursley8]

I am not positive what you are asking, but the FFT.vi output is complex so maybe you are only seeing the real part of the signal?