Currently, there is a significant increase in the number of violations of the airspace by small aircrafts in civilian protected areas, such as airports, crowded areas, industrial enterprises, etc. In this regard, the task of detecting, determining the coordinates and tracking air objects crossing the guarded perimeter and used both for video filming and for the delivery of goods becomes especially urgent. Often used locating tools located on the territory have blind spots, or observation of objects is difficult, which is mainly observed in dense urban development. The paper presents the advantages and disadvantages of radar and optical monitoring systems allowing for real-time observation. The problem of processing frames of the video stream of optical and radar images for the purpose of tracking, as well as extrapolating the coordinates of the position of unmanned aerial vehicles in the event of a temporary loss of visibility, including full shading, partial shading or other types of natural interference. To solve this problem, a method is proposed based on the use of a set of adaptive filters tuned to various types of motion of objects in order to predict their position.
In radar systems, when solving the problem of detecting objects behind dielectrically transparent obstacles against a background of noise and interference, methods of compressing modulated UWB signals are often used. The most widespread in solving this problem are Barker codes, which are binary sequences of finite length N = 2,3,4,5,7,11,13. One of the main features of Barker codes is the equality of the amplitudes of all lateral maxima of the autocorrelation function at their minimum possible level not exceeding 1 / N. Code sequences with such properties have not been found for N< 13. Recently, the theory of quasi-orthogonal matrices has arisen and is being developed, which include the Mersenne and Raghavararo matrices. Mersenne matrices exist in all orders N = 4n-1, where n is a natural number. The indicated matrices, which are the kernel of the Hadamard matrices and generalize them, can have both cyclic and symmetric constructions. In this paper, we consider the modulation of UWB signals using the Mersenne and Raghavararo codes obtained from the rows of the corresponding quasi-orthogonal matrices. The compression characteristics of code-modulated signals in comparison with Barker codes are investigated by the method of simulation modeling. The results of evaluating the compression characteristics of the considered signals showed the advisability of using, for example, for N = 13 the Raghavararo code instead of the Barker codes. This provides greater noise immunity of UWB signals in the channels for detecting objects behind obstacles. Since, in addition to radar systems, the Barker sequence of length 11 is widely used in digital data transmission systems, the developed simulation model and the results obtained using Mersenne codes are of great theoretical and practical importance in studies of noise immunity in digital UWB data transmission channels in a complex electromagnetic environment.
The article discusses the possibility of using a two-position onboard optical-location system for detecting, classifying and determining the coordinates of the trajectory of objects in the video stream installed on the small aircraft. Every year the requirements for new monitoring systems are becoming more stringent. The data obtained from a single, albeit highquality, optical sensor can no longer meet the assigned tasks, such as performing search and rescue operations in remote areas, as well as solving problems of finding people in disaster zones. and environmental disasters in a complex noise environment. The system considered in the article includes optical-location sensors, each of which is capable of forming a high-resolution image and classifying the observed objects, as well as, when used together using stereo vision methods, to obtain estimates of the coordinates of the object's trajectory. observed objects. It is shown that combining information in an optical location system allows detecting, classifying and determining the parameters of motion of objects, including people and animals. The article presents the operating modes of the system, and the corresponding restrictions on the conditions for its effective operation.
The article provides an analysis of new code structures of maximum length obtained from rows of quasi-orthogonal matrices. Codes of maximum length (m-sequences, codes constructed on the basis of Legendre symbols or quadratic residues, codes generated on the basis of Jacobi symbols and others) have the potential to be widely used both in remote sensing radar systems and in noise-immune and noise-proof systems high-speed communications as a replacement for widely used Barker codes. The questions of searching and researching new noise-resistant codes constructed on the basis of persymmetric circulants are considered. Comparison of performance ratings obtained with the new code sequences is given. The advantages of the codes obtained in the work are discussed in the aspects of increasing the correlation characteristics, their detection, and noise immunity in the radio channels of distributed systems. Since these codes have potential applications in radar, not only the correlation properties (autocorrelation and periodic correlation function) are considered, as for communication systems, but also the ambiguity function, which takes into account not only the correlation of signals in time, but also in frequency. The results show the possibility for their use in distributed location systems, not only in the case of remote sensing of the earth, but also in the field of application of the transmission of generated signals to points of joint information processing.
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