The degree of agreement between two unlike signals.

a way of determining how similar two signals are using a weighted moving average

The mathematically derived measure of similarity between two functions or signals. Cross-correlation also refers to the process of determining this similarity, and is accomplished by multiplying the two signals together and integrating the result over time. If the result is zero, the two signals are said to be uncorrelated, or orthogonal.

A measure of the similarity of two different signals.

In statistics, the term cross-correlation is sometimes used to refer to the covariance cov(X, Y) between two random vectors X and Y, in order to distinguish that concept from the "covariance" of a random vector X, which is understood to be the matrix of covariances between the scalar components of X.