Howtosignalprocessing
Variance of a signal is the difference between the normalized squared sum of instantaneous values with the mean value. In other words it provides you with the deviation of the signal from its mean value. It gives you the spread of your signal's data set.
What is σ variance?
The variance is the the sum of squared deviations from the mean. The variance for population data is denoted by σ2 (read as sigma squared), and the variance calculated for sample data is denoted by s2.
Is variance the same as power?
We can describe variance as the averaged power of the signal's random deviations expressed as power. This means that variance doesn't have the same unit as the values that we started with.
What is the standard deviation of a signal?
The standard deviation is a measure of how far the signal fluctuates from the mean. The variance represents the power of this fluctuation. Another term you should become familiar with is the rms (root-mean-square) value, frequently used in electronics.
