V.A. Nenashev

Saint-Petersburg State University of Aerospace Instrumentation (St. Petersburg, Russia)

Formulation of the problem. Small-sized airborne radars based on small unmanned aerial vehicles. They have a small aperture of antenna devices, which leads to a wide radiation pattern and, accordingly, to a low accuracy in determining the azimuthal coordinates when detecting ground-based physical objects. To improve accuracy under these conditions, multi-position airborne radars are used. In the simplest case, two-position airborne radars, which, when integrating information about detected objects, allow, with a small antenna aperture, to increase the accuracy of determining the azimuthal coordinates by an order of magnitude or more. In this case, when an object is detected by a two-position radar system, the accuracy estimate is an interval estimate determined by the extreme dimensions of the resolution element of the two-position system. In such a system, the midpoint of the angular azimuthal resolution element in which the physical object is detected is taken as a point estimate. However, other point estimates are possible, which can be strictly computed by specifying the distribution of the object's location in the bin. These point estimates are the mean of the distribution and the median.

In this work, an equiprobable distribution of the location of a physical object in the resolution element is accepted and the distribution densities of the location of the detected object are analytically calculated depending on the azimuthal coordinates of the onboard radar of the two-position system. On the basis of these distribution densities, point estimates of the azimuthal coordinates of the object were obtained for two onboard radars using the middle of the angular azimuthal resolution element, mathematical expectation and median. 

Research methods. The study used the methodology for constructing multi-position onboard location systems, methods of probability theory and mathematical statistics, methods of simulation and numerical study of systems on a computer.

Results. Analytical expressions and tables of values for point estimates of the azimuthal coordinates of a detected physical object in a two-position system of onboard radars are obtained in this work.

Practical significance. The proposed assessments in real conditions can be used, for example, for environmental monitoring using appropriate sensors, for assessing the state of the environment, as well as for timely and prompt search and rescue of people in the zone of man-made disasters and disasters in the event of emergencies. At the same time, the key factor is to reduce the search time, which significantly depends on the accuracy of determining the coordinates of objects, which can be radio beacons that send an SOS signal.

Nenashev V.A. Comparative characteristics of the accuracy of determining the azimutal coordinates of objects in a two-positional system of small airborne radar. Science Intensive Technologies. 2021. V. 22. № 8. P. 29−37. DOI: https://doi.org/10.18127/j19998465-202108-04 (in Russian)

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11. Nenashev V.A., Shepeta A.P., Kryachko A.F. Fusion radar and optical information in multiposition on-board location systems. XXIII International Conference on Wave Electronics and Infocommunication Systems, 1–5 June 2020. St.-Petersburg. Russia. P. 1–5.
12. Nenashev V.A., Sentsov A.A., Shepeta A.P. Formation of Radar Image the Earth's Surface in the Front Zone Review Two-Position Systems Airborne Radar. Wave Electronics and its Application in Information and Telecommunication Systems (WECONF), SaintPetersburg, Russia. 2019. P. 1–5. 
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14. Patent № 2560082 C2 (RF), MPK G01S 13/90. Sposob frontal'nogo sintezirovaniya apertury antenny zemnoj poverhnosti s isklyucheniem slepyh zon v perednej zone s pomoshch'yu mnogopozicionnoj radiolokacionnoj sistemy. A.P. SHepeta, YU.F. Podoplekin, V.A. Nenashev. 2015 (in Russian).