Standard Deviation

March 29, 2018

The standard deviation (σ) measures a signal’s variability about its mean value. Equation 6 gives the standard deviation of a set of numbers, x_n, n = 1, …, N.

(1) $\begin{equation*} \sigma=(+)\sqrt{\sigma^2} \end{equation*}$

Equation 6

A vibration signal with a mean value of zero has a standard deviation equal to the signal’s root-mean-square (RMS) value. For the vibration signal in Figures 3.1 and 3.2, the standard deviation and RMS level have a value of 0.073 G.