The vibration of the machine is a physical motion. Vibration Transducers convert this motion into an electrical signal. The
electrical signal is then passed on to analyzers. The analyzers then process this signal to give the Fast Fourier Transform [FFT].
The most widely used conventional analysis in the frequency domain is the spectrum analysis using FFT. The most commonly
used tool in spectrum analysis is power spectrum which is a positive real function of a frequency variable associated with a
stationary stochastic process, or a deterministic function of time, which has dimensions of power per hertz (Hz), or energy
per hertz, which is often called simply the spectrum of the signal. Intuitively, the spectral density measures the frequency
content of a stochastic process and helps identify periodicities. In this paper, frequency-domain analysis is utilized for
calculation of SER. Theory behind calculation of SER is explained in this section.