In this paper, the trivariate probability density function (PDF) for the en
velope of a bandpass Gaussian process Is derived. However, the multivariate
PDF for the envelope of a bandpass Gaussian process having an arbitrary po
wer spectrum has been previously reported. The Markovian behavior of the en
velope process for the U-shaped poser spectrum 1/root 1 - f(2) is studied b
y H. S. Wang and P. C. Chang using an information theoretic approach. It is
worth mentioning that several authors have formerly discussed that Markovi
an behavior for the rational power spectrum 1/(1 + f(2)) from a probabilist
ic point of view.