Yu. K. Sveshnikov, A. A. Vasenina

The paper introduces one of the features of adaptive low-energy HF radiolines - ageing of route probing results, which determine a choice of highest probable frequency. Therefore, this choice and adaptation to quickly varying conditions of communication is carried out during short time lags that results in a problem of signal-to-noise ratio estimation. The purpose of signal-to-noise ratio estimation in adaptive HF radiolines except for a choice of the best allowed working frequency for communication is a choice of the most probable technical speed at allowable communication reliability. Risk of the choice of inconsistent model of HF signal distribution, as well as absence of single indisputable model of noises in HF band leads to search of method of estimation of coherent signals and processing methods, invariant both to model of distribution, and to model of noises. The description of rank method of estimation of signal-to-noise ratio in a low-energy short-wave link is given as well as the choice of technical speed and highest probable frequency on the basis of it. Linear and rank methods are compared by signal-to-noise ratio. Advantages of a rank method over a linear method by signal-to-noise ratio are analyzed. The paper presents dependence of the sum of ranks on discrete frequency modulated signal matrix from signal-to-noise ratio being the result of computing experiment. Calculation was carried out with use of a rank method on a background of additive white Gaussian noise. During the modeling the signal was formed as a time-and-frequency matrix with dimension N×N using algorithm of construction of optimum systems of discrete frequency signals. The algorithm of a choice of optimum speed in a particular HF channel in a concrete line of distribution at known parameters of discrete frequency modulated signals by means of a calculated curve is stated. The calculated curve was compared with the experimental curve and then was corrected. The paper contains the results of bench and route tests of low-energy radio links in various length routes showing high operability of a rank method of signal-to-noise ratio estimation.