Power Spectral Density Estimates Using FFT

I used PSD through FFT and the numbers in my plot (Y-axis) are not less than 1 as I expected to see in PSD result. I attached the sample function and the plot. Is something wrong with my function that should be changed?

Answer 1

[vijaya lakshmi]

Hi Mo,

To compute the power spectral density using the FFT function, the absolute value FFT output has to be squared and scaled by (1/length(data))*(1/Fs) where Fs is the sampling frequency. This result is then converted to decibels.

I observe that you haven't converted the result in decibels.This might be causing to the numbers along y-axis to be greater than 1.