D.V. Nefedov - Ph.D. (Eng.), Researcher, Kotelnikov IRE RAS (Saratov branch). E-mail: nefedov_dv@rambler.ru S.Yu. Suzdaltsev - Ph.D. (Eng.), Senior Researcher, Kotelnikov IRE RAS (Saratov branch) V.Ya. Shanygin - Senior Engineer, Kotelnikov IRE RAS (Saratov branch) R.K. Yafarov - Dr.Sc. (Eng.), Head of the Laboratory, Kotelnikov IRE RAS (Saratov branch)