Correlation, 3

This is an even function, that is the curve is symmetrical about an axis ( https://www.w3.org/1998/Math/MathML" display="inline"> τ = 0 ). It presents a maximum at ( https://www.w3.org/1998/Math/MathML" display="inline"> τ = 0 ) because it is in this relative position that the curves which are to be correlated have their samples in phase. The correlation in this position may be considered perfect. A schematic diagram showing several seismic signal traces plotted against time t, with a selected time window marked. The lower trace displays the autocorrelation function labelled A C F of g(t), plotted against lag time tau, highlighting a central peak that represents signal similarity and periodicity. https://www.w3.org/1999/xlink" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003761020/e10523ab-dbe3-4c4f-8f3e-863ae3683950/content/pg39_1.tif "/>