Vlasenko D. Optimization of secondary spatio-temporal signal processing in aerospace cognitive radar for radio vision

The dissertation research is focused on the development and study of methods of secondary spatio-temporal signal processing in aerospace cognitive radars for radio vision. These methods are proposed to be used as a supplement to classical onboard radar systems with antenna arrays and synthesis of the antenna aperture. Thus, the aim of the study is to improve the quality of radar images by using aerospace cognitive radar with optimal secondary spatial and temporal signal processing. The object of research is the process of signal processing in on-board cognitive radar systems of high-precision radio vision. The subject of the study is methods, algorithms and devices for secondary spatio-temporal signal processing in on-board radar systems with antenna arrays and synthesis of aperture. This research was prompted by the fact that in aerospace radars there is a contradiction between the width of the viewing band and high azimuthal resolution. The fact is that when expanding the radar's viewing area with range synthesis of the aperture, it is necessary to reduce the pulse repetition rate, but this results in ambiguity of azimuth measurements. Conversely, to synthesise a single, gapless, and long aperture along the flight path of an aircraft, it is necessary to increase the pulse repetition rate, which leads to ambiguity in range. To resolve this contradiction, it is advisable to use the concept of so-called cognitive radars, which provide adaptive tuning of the transmitter, receiver and phased array, the use of a priori information about the area of observation, and the availability of feedback. However, most of these radars are built using heuristic methods, based on engineering intuition, summarising the practical experience of building and using synthetic aperture radar (SAR) and do not allow to unlock their full potential. The closest statistical theory of radio system synthesis that reveals algorithms for adaptive tuning of reference signal generators and receiving paths is the theory of nonlinear filtering and secondary signal processing. At the same time, the main efforts of researchers in this area are aimed at synthesising new methods for tracking the phase, frequency and amplitude of signals. In this regard, this thesis was the first to solve the relevant problem of statistical synthesis of optimal methods of secondary spatio-temporal signal processing in aerospace cognitive radars for the formation of high-quality radio images of surfaces. As a result of solving this problem, the concept of building aerospace cognitive radars for the formation of radar surface images was further developed, which, unlike the existing ones, involves solving the optimisation problem of statistical synthesis of secondary spatio-temporal signal processing algorithms for optimal integration of an adaptive multichannel transmitter, adaptive multichannel receiver, phased array, dynamic environmental database and intelligent processor in a single system. The optimal method of secondary processing of spatio-temporal signals in aerospace cognitive radars for underlying surface radar was synthesised. The optimization problem of synthesis of digital algorithms for filtering the complex scattering coefficient of the underlying surface in on-board aerospace cognitive radars of radio vision was solved. The principles of construction of aerospace radars of the underlying surface have been improved, which implement the synthesised method of secondary processing of spatio-temporal signals, consider all the necessary components of the cognitive radar and allow to form high-quality radar images of the Earth's surface.