Increasing the energy secrecy of narrow-band signals of satellite communication systems during transionospheric propagation of radio waves through an inhomogeneous ionosphere due to a decrease in carrier frequencies and space-diversified reception. Part 1. Statement of the problem of increasing energy secrecy and its solution
The relevance is due to the fact that the solution of the problem of designing advanced satellite communication systems (SCS) should be based on an integrated approach, which involves taking into account all the parameters and restrictions that provide both the requirements for the efficiency of its operation, including the requirements for both noise immunity and its secrecy from means of radio and electronic intelligence (REI). A known method of increasing the energy secrecy of the SCS with a close placement of the radio detection receiver by lowering the carrier frequency and the use of space-diversified signal reception. As a quantitative criterion of the achieved level of energy secrecy of the SCS, such a generally recognized indicator as the coefficient of energy secrecy (ECS) of the SCS is used. However, the well-known method for determining the ECS is graphic-analytical. Therefore, it does not allow automating the process of determining this indicator using modern computer technology, which makes it difficult to solve the problem of designing promising SCS. In the first part of the article, the numerical methods of bisection, chords, Newton and the Newton-chord method, which are traditionally used to refine the root of a nonlinear equation with one unknown, were considered and adapted to determine the values of the energy signal-to-noise ratio (SNR) at the input of a satellite earth station receiver communication and at the input of the radio detection receiver of the RRTR means. Thus, the necessary prerequisites have been implemented for the implementation of the methodology for the automated assessment of CES SCS, which allows, even at the stage of pre-contract work, to determine the potential energy secrecy of the designed CCC, taking into account the capabilities of the party implementing the RRTR. The aim of the work is to analyze the possibility of increasing the energy secrecy of narrow-band signals of satellite communication systems with low carrier frequencies based on the development of a methodology that allows to reduce time costs and improve the accuracy of estimating the ECS of the SCS, by using numerical methods instead of graphical methods to refine the roots of nonlinear detection and noise immunity equations and their implementation in MATLAB. Results and their novelty. The developed methodology for evaluating the ECS of satellite communication systems differs from known in that it allows you to reduce the time for assessing this coefficient from hours to units of seconds and at the same time reduce the error of its assessment by at least three orders of magnitude. In addition, for the first time, original analytical expressions were obtained for calculating the first and second derivatives of the Marcum Q-function with respect to the signal-to-noise energy ratio parameter, which are necessary for the software implementation of the numerical Newton and Newton-chord methods for refining the roots of the nonlinear detection equation. The practical significance is that the developed methodology for evaluating the ECS of satellite communication systems will be useful to technical specialists to substantiate the source data necessary for calculations on clarifying the parameters of promising satellite communication systems, taking into account the simultaneous provision of requirements, both for the required noise resistance and in secretions connections. In addition, this technique may be of interest to scientists and applicants leading scientific research in the field of satellite communication.