S. N. Zamuruev - Dr.Sci. (Eng.), Moscow State Technical University of Radio Engineering, Electronicsand Automation. E-mail: zamuruev@mirea.ru
R. P. Bystrov - Dr.Sci. (Eng.), Professor, Kotel'nikov's Institute of Radioengineering and Electronics (IRE) of Russian Academy of Sciences (Moscow). E-mail: rudolf@cplire.ru
P. Yu. Chesnokov - Post-graduate Student, Moscow State Technical University of Radio Engineering, Electronics and Automation. E-mail: chesnokoff-p@inbox.ru
A. V. Chendarov - Head of division, Department of Radio Electronics Industry of The Ministry of Industry and Trade of the Russian Federation

The problem of analyzing digital line parameters in a local autonomous radio navigation system with due account for information link critical parameters was considered. To estimate effect of channel parameters (or high-frequency propagation conditions) of a digital data transmission system, there was substantiated a selection criterion for the optimal communication channel, with error probability per elementary symbol being chosen as this criterion. The channel transmission coefficient distribution is suggested to be approximated with m-distribution, which is very flexible at adjustment to a real law and allows a sufficiently simple calculation procedure. General correlations interconnecting information link critical parameters were determined. As real technical information rate decreases because of necessity to spend some of the overall transmission time on clock signal transfer as well as on guard spaces between code combinations, it was suggested to perform the noise immunity analysis on the first stage with simplifying assumptions. On the second stage, the aim is to provide such operating conditions and to choose parameters in such a way, that man-made assumptions will be acceptable. To estimate calculating errors, a factor correcting information rate decrease is applied, its value in real information channels can be of the order of 0,6-0,9 depending on actual operating conditions, channel parameters, and the like.