A signal is said to be a band limited signal, if all of it's frequency components are zero above a certain finite frequency. i.e it's power spectral density should be zero above the finite frequency.
Stochastic
systems whose behaviour is intrinsically non-deterministic. A stochastic process is one whose behavior is non-deterministic.
What is power spectral density function?
Power spectral density function (PSD) shows the strength of the variations(energy) as a function of frequency.
obtain energy within a specific frequency range by integrating PSD within that frequency range.
Computation of PSD is done directly by the method called FFT or
computing autocorrelation function and then transforming it.
FFT plot SNR
The SNR of the FFT calculation is a combination of several noise sources, including
the quantization error of theADC,
the internal noise of the ADC,
noise from the voltage reference, and
noise from the driving amplifier.
The theoretical limit of SNRis 6.02n+1.76 dB, where n is the number of converter bits.