S.D. Tyrnov - Engineer, JSC «A.L. Mints Radiotechnical Institute» (Moscow). E-mail: styrnov@rti-mints.ru R.A. Shevchenko - Main Designer, JSC «A.L. Mints Radiotechnical Institute» (Moscow). E-mail: shevchenko@rti-mints.ru S.P. Pryadkin - Ph. D. (Eng.), Associate Professor, Leading Research Scientist, JSC «A.L. Mints Radiotechnical Institute» (Moscow). E-mail: pryadkin.serg@gmail.com

The article is devoted to the problem of construction of the radio line-of-sight propagation to link the microwave range between ground control station (GCS) and unmanned aerial vehicle (UAVs). Article describes an algorithm for calculating the zone of the radio line-of-sight propagation with building an open, semi-closed and closed intervals. Unlike most existing algorithms, focused on the construction zone along the radio beam (point to point), for command and information exchange it is necessary to form spatial zone of the radio line-of-sight propagation, when driving on the route of the UAV. At the same time the existing iteration-step approach is practically inapplicable due to a sharp increase in computing resources for remote management of airmobile object in real time. According to the model of the geoid, and the model of diffraction loss in the radio channel of microwave range the radio line-of-sight propagation zone is calculated and the digital Earth surface maps of planning UAV flight mission is marked via an open, semi-closed and closed intervals. In addition a continuous radio line-of-sight propagation zone on the flight map is calculated and in which the UAV is in the open range also it has a minimum altitude required for stable operation of the radio channel. The radio line-of-sight propagation model consists of 4 main points. First point, the construction of a spatial map based on land relief. Second point, a conformal mapping the vector space of the nodal points on a spatial map. Third point, sorting grid points on the basis of geometrical radio line-of-sight propagation for converted a vector space. Fourth point, the colors of the grid points based on the diffraction loss of the obstacles in the terrain of the first Fresnel-s zone. The algorithm is based on the method of conformal mapping of the original vector space via analytic univalent in the finite domain of the function. The novelty of the approach in the construction zone of the radio line-of-sight propagation is to use conformal mapping of the original vector space (heights and distances calculated based on SRTM maps) in to the K-Space (angular coefficients and ranges). Created a linear classifier of state the radio line-of-sight propagation zone (classifier provides marking waypoints of UAVs). It has been done analytical estimation of the accuracy of the radio line-of-sight propagation zone. It has been done calculation of continuous radio line-of-sight propagation zone. And it is determined UAVs margin altitude to ensure a stable connection. The algorithm is different from the existing in single pass implementation and low requirements for computing resources. This enables its use for remote control of the UAV on a spatial trajectory in real time. The algorithm is shown to be effective, since it leads to an acceptable compromise between the two conflicting requirements - build up a spatial zone of the radio line-of-sight propagation of the channel GCS-UAV and ease of implementation.

 

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