Table 1.

Time domain SF’s extracted from the FSFB. The x(n) is FSFB in the time domain, N is the sample data points.

Feature Name	Equation	Feature Name	Equation
Mean	$X_m=\frac{{\displaystyle \sum _{n=1}^{N}x(n)}}{N}$	Variance	$X_v=\frac{{\displaystyle \sum _{n=1}^N{(x(n)-X_m)}^2}}{(N-1)}$
Root amplitude	$X_{root}={\left[\frac{{\displaystyle \sum _{n=1}^N\sqrt{\left|x(n)\right|}}}{N}\right]}^2$	Skewness	$X_{sk.}=\frac{{\displaystyle \sum _{n=1}^N{(x(n)-X_m)}^2}}{(N-1)X_{sd}^3}$
RMS	$X_{rms}=\sqrt{\frac{{\displaystyle \sum _{n=1}^N{(x(n))}^2}}{N}}$	Clearance factor	$X_{clearance}=\frac{X_{peak}}{X_{root}}$
Impulse factor	$X_{impulse}=\frac{X_{peak}}{\frac{1}{N}{\displaystyle \sum _{n=1}^N\left|x(n)\right|}}$	Kurtosis	$X_{kurtosis}=\frac{{\displaystyle \sum _{n=1}^N{(x(n)-X_m)}^4}}{(N-1)X_{sd}^4}$
Shape factor	$X_{shape}=\frac{X_{rms}}{\frac{1}{N}{\displaystyle \sum _{n=1}^N\left|x(n)\right|}}$	Peak value	$X_{peak}=\max \left|x(n)\right|$
Standard deviation	$X_{sd}=\sqrt{\frac{{\displaystyle \sum _{n=1}^N{(x(n)-X_m)}^2}}{N-1}}$	Crest factor	$X_{crest}=\frac{X_{peak}}{X_{rms}}$