Origin Version (Select Help-->About Origin): Pro7 Operating System:xp Hi, Please verify if my assumptions about the relationship between the Normalised FFT amplitude and the signal amplitude is right:
Signal Amplitude = Normalised FFT Amplitude/2.
FFT Power = (Normalised FFT Amplitude)^2/Number of points
There are more tha one FFT normalization methods but I assume you are talking about Analysis > FFT. According to the Origin Reference...
quote:Normalization in a Forward FFT divides the Real results by N/2 (both AC and DC components). Normalization in a Backward FFT divides the Real results by 2, except for the DC component which is left unchanged.
and
quote:The Power is derived from the Real^2/N, where N is the number of points
The first normalization occurs only when the Normalize Amplitude FFT setting is checked. The power normalization is independent of that setting.
2. The peak area will be the same. For a perfect sinusoid the peak is a delta function with area under one point. Apodization (windowing) broadens the peak so peak height must decrease to maintain same area.