Hennadii Khudov et al., International Journal of Emerging Trends in Engineering Research, 8(6), June 2020, 2624 - 2630 2624 ABSTRACT The subject of the article is the task of developing a coherent signals processing method in the multiradar system of the same type two-coordinate surveillance radars with mechanical azimuthal rotation. The goal of the paper is solving the problem of developing a coherent signals processing method in multiradar system based on radars with mechanical rotation. It has been found that, in modern-day hybrid wars, founding a reliable air defence system is made much more difficult by the appearance of low radar cross section air objects. It is proposed to increase the energy potential of existing surveillance radars by integrating them into a spatially spaced coherent multiradar system. To ensure a consistent overview of the airspace, the locations of the radars are made in a single line with their synchronous azimuthal rotation. The transmitting signals must be simultaneously transmitted and orthogonal by frequency diversity or encoding. The synthesis of the optimal coherent signal finder is performed. The characteristics of detection of air objects in a multiradar system with mutually coherent signals are evaluated, when all radars emit identical signals in such a way that their common-purpose summation is secured. The following results were obtained: the highest efficiency in signal/noise gain was shown by the addition of a second radar, the optimum number of radars in the multi-radar system of no more than four. Therefore, the most cost-effective criterion is to create a spatially coherent multiradar system by combining two to four similar radars. In this case, the expected gain in the threshold signal-to-noise can be up to eighteen decibels. The use of more than four radars is impractical because it does not lead to a significant increase in the gain. The direction of further researches is the development of a non-coherent mutually processing signals method in a multiradar system-space spatially spaced two-coordinate radar observation stations with mechanical azimuthal rotation. Key words: radar, multiradar system, air object, coherent processing, detection curve, probability of correct detection, probability of false alarm. 1. INTRODUCTION In the context of modern hybrid and network-centric wars, the anti-terrorist operation and the Joint Forces operation in eastern Ukraine, the construction of a reliable air defence system in general and its reconnaissance information subsystem is significantly complicated by the appearance of small visibility (with low radar contrast) ) and small air objects [1]–[8]. It is known from the experience of last local wars and the anti-terrorist operation and the Joint Forces operation that small UAVs in most cases were not detected by the available means of radar of the radar troops [2]–[5], [9], which form the basis of the air defence information subsystem. The following problems significantly reduce the effectiveness of the using of radar troops [10]–[16]: – the radar air surveillance system is not able to provide guaranteed detection and maintenance of the air object in general and inconspicuous objects in particular; – deficiency of sufficient number of new and modernized samples of electronic equipment, means of automation of collection, processing and issuance of radar information in radio engineering units to provide information about the air object at low and extremely low altitudes, and others. Hennadii Khudov 1 , Vitaliy Lishchenko 2 , Boris Lanetskii 3 , Vadym Lukianchuk 4 , Stanislav Stetsiv 5 , Ivan Kravchenko 6 1 Department of Radar Troops Tactic, Ivan Kozhedub Kharkiv National Air Force University, Kharkiv, Ukraine, 2345kh_hg@ukr.net 2 Department of Radar Troops Tactic, Ivan Kozhedub Kharkiv National Air Force University, Kharkiv, Ukraine, lvnpo4ta@gmail.com 3 Scientific center of Air Force, Ivan Kozhedub Kharkiv National Air Force University, Kharkiv, Ukraine, Laneckij.B.hnups@gmail.com 4 Scientific center of Air Force, Ivan Kozhedub Kharkiv National Air Force University, Kharkiv, Ukraine, super.vadim1973@ukr.net 5 Department of Missile Forces, Hetman Petro Sahaidachnyi National Army Academy, Lviv, Ukraine, 2345kh_hg@ukr.net 6 Data-Processing Computer Centre, Ivan Kozhedub Kharkiv National Air Force University, Kharkiv, Ukraine, kravchenkoivan@ukr.net The Coherent Signals Processing Method in the Multiradar System of the Same Type Two-coordinate Surveillance Radars with Mechanical Azimuthal Rotation ISSN 2347 - 3983 Volume 8. No. 6, June 2020 International Journal of Emerging Trends in Engineering Research Available Online at http://www.warse.org/IJETER/static/pdf/file/ijeter66862020.pdf https://doi.org/10.30534/ijeter/2020/66862020