Classification of Trajectories of Hidden Motion of an Airborne Object in the Detection Zone of an Onboard Doppler Radar
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ROL SYSTEMS OF MOVING OBJECTS
Classification of Trajectories of Hidden Motion of an Airborne Object in the Detection Zone of an Onboard Doppler Radar Station A. P. Kirsanov National Research University Higher School of Economics, Moscow, 101000 Russia e-mail: [email protected] Received January 10, 2020; revised February 28, 2020; accepted March 30, 2020
Abstract—It is shown that due to the peculiarities of the detection zone of an airborne radar station of a long-range radar detection system operating in the pulse-Doppler mode, there are hidden trajectories in which airborne objects (AOs) are not detected by the airborne radar station. Solutions to differential equations describing hidden trajectories are found. The hidden trajectories are classified. Phase portraits corresponding to various types of hidden trajectories are constructed. The conditions are found on the motion parameters of an AO and aircraft of long-range radar detection, upon fulfillment of which a hidden trajectory is realized.
DOI: 10.1134/S1064230720040097
INTRODUCTION A limited horizon is one of the factors that reduce the detection range of ground-based radar stations (RSs) relative to airborne objects (AOs) flying at low altitudes. Therefore, to increase the detection range of low-flying AOs, the RS antennas are placed on hills or special masts. This makes it possible to increase the radio horizon. However, the most radical solution to the problem of the limited radio horizon of a ground-based RS is the placement of an RS on an aircraft. The most widely used are multifunctional aviation systems for airborne early warning (AEW) or aviation systems for radar monitoring and guidance (AKRLDN) in the Russian terminology. The base of such systems is the all-round RS installed on special aircraft [1, 2]. Placing an RS on an airplane solves the problem of a limited radio horizon but also, as often happens, leads to another problem. In this case, there is a need to detect low-flying AOs in the background of the underlying surface, which leads to the appearance of peculiarities in the detection area of the onboard RS of an AEW aircraft. These features are related to the use of the pulsed-Doppler mode of operation of the onboard RS of an AEW aircraft [1–3] and consist of the appearance at each point of the detection zone of the directions of motion of the AO, for which the radial components of the velocity of the AO and the underlying surface coincide, and therefore the AO cannot be detected by an RS with Doppler signal filtering. The features of the Doppler RS detection zone are considered in more detail in [4]. Due to such features, hidden trajectories can be constructed in the field of view, i.e., such trajectories, along which an AO’s motion is not detected by the airborne RS of the AEW system. In [5], differential equations were derived whose solutions are hidden trajectories. For an important special case, various types of the so-called orthogonal hidden trajectories were found and described. However, the orthogonal hidden trajectories investigated in [
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