Random processes are of great and ever increasing interest to scientists and engineers working in various branches of radio physics. This is quite understandable, since at the present stage of technological development, random noise constitutes the chief obstacle to further improvement of certain engineering devices. In fact, a current problem in many fields of radio physics is that of evolving techniques for analysis and design of equipment which immune to noise. Convincing proof of the importance and urgency of this subject is afforded by the large number of books devoted to it, published both in the U.S.S.R. and elsewhere.