Autocorrelation is the cross-correlation of a signal with itself. Informally, it is the similarity between observations as a function of the time separation between them. It is a mathematical tool for finding repeating patterns, such as the presence

随机信号的统计特性测试,均值、方差，相关函数（包括自相关、互相关函数）、频谱及功率谱密度算法.-The statistical properties of random signal test, mean, variance, correlation function (including autocorrelation, cross-correlation function), spectrum and power spectral density algorithms.