q)series of which mean and variance may vary with time is widely used in engineering
such as pattern recognition
fault diagnosis
signal processing
automatic control
structure response analysis and so on.The traditional correlation function stationary ARMA(p
q) model is just a special case of that.The conditional maximum likelihood estimation (MLE) and exact MLE for the correlation coefficient ARMA(p
q) series are established in this paper
which can obtain its mean function
variance function and correlation coefficient function with high precision.The conditional MLE is simple and convenient for engineering application when the sample is large enough
and the exact MLE is still precise in the case of small sample. Base on analyzing in time domain
the spectral analysis of correlation coefficient ARMA(p