V. A. Ufaev - Dr.Sc. (Eng.), Senior Research Scientist, Leading Research Scientist of - VVA n.a. prof. N.E. Zhukovsky and Yu.A. Gagarin - (Voronezh)
A. V. Ufaev - Design Engineer, JSC - Concern "Sozvezdie" (Voronezh)

Applied to multiport systems of reception and direction finding selection algorithms with evaluation radiated power and the source location on the surface of radio waves reflected from the ionosphere background signals have been synthesized by method of testing statistical hypotheses. The model of radio wave propagation near the earth's surface and the attenuation factor calculation method Shuleykina-Van-der-Pol are used. The variants of the single-stage signal processing antenna arrays, two-step processing of field strength measurements, one-and two-dimensional bearings have been considered. In the latter case, the crucial statistic is the sum of functions of uncertainty in bearing and field strength, each of which is the sum of the points of reception and direction finding squares of calculated and measured parameters. The statistical characteristics of critical statistics and the effectiveness of selection-evaluation are investigated by statistical modeling method. The system with an equidistant arrangement of direction finding points on a circle of radius 5 km was investigated. Availability of surface area of the electromagnetic radio waves was limited by radius of 30 km. The 10 watt emitter with a wavelength of 25 m was equally probable located in this area. Ionospheric propagation conditions were modeled for typical winter day with sources in the ring at a distance of 354 to 4863 km. The simulation results showed that the decisive statistics are chi-square distribution, the analytical relations for calculating the number of degrees of freedom are given. It has been established that the inclusion of the amplitude of the field intensity dependence on the distance allows to evaluate additionally the radiation power and the source coordinates in the direction along the base of direction finding. With approximately 3,5 times less chance of false alarms, the direction along the base is also characterized by up to three times fewer errors of assessment, which is not typical for the classical angular dimensional systems. It has been found that it is preferable to use a one-step process or equally effective selection method for two-dimensional direction finding and amplitude with a smaller volume of recorded information.