Nested code sequences of Barker — Mersenne — Raghavarao
21 Jun 2019-Iss: 3, pp 71-81
TL;DR: Nested code sequences derived from the rows of quasi-orthogonal cyclic matrices of Mersenne, Raghavarao and Hadamard are studied, providing estimates for the characteristics of the autocorrelation function of nested Barker, MERSenne and Raghavao codes, and their combinations.
Abstract: Introduction: The problem of noise-free encoding for an open radio channel is of great importance for data transfer. The results presented in this paper are aimed at stimulating scientific interest in new codes and bases derived from quasi-orthogonal matrices, as a basis for the revision of signal processing algorithms.Purpose: Search for new code sequences as combinations of codes formed from the rows of Mersenne and Raghavarao quasi-orthogonal matrices, as well as complex and more efficient Barker — Mersenne — Raghavarao codes.Results: We studied nested code sequences derived from the rows of quasi-orthogonal cyclic matrices of Mersenne, Raghavarao and Hadamard, providing estimates for the characteristics of the autocorrelation function of nested Barker, Mersenne and Raghavarao codes, and their combinations: in particular, the ratio between the main peak and the maximum positive and negative “side lobes”. We have synthesized new codes, including nested ones, formed on the basis of quasi-orthogonal matrices with better characteristics than the known Barker codes and their nested constructions. The results are significant, as this research influences the establishment and development of methods for isolation, detection and processing of useful information. The results of the work have a long aftermath because new original code synthesis methods need to be studied, modified, generalized and expanded for new application fields.Practical relevance: The practical application of the obtained results guarantees an increase in accuracy of location systems, and detection of a useful signal in noisy background. In particular, these results can be used in radar systems with high distance resolution, when detecting physical objects, including hidden ones.
Citations
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TL;DR: 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.
Abstract: 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.
1 citations
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TL;DR: The theoretical problems of designing sector surveillance radars using electronic scanning and rho-theta method are touched, and the limitations on the measurement distance and angular coverage are discussed.
Abstract: The paper discusses the structure of a distributed radar system for detecting and locating airborne objects. We touch the theoretical problems of designing sector surveillance radars using electronic scanning and rho-theta method. The location is performed by matching the data from two small radars. This improves the accuracy of the moving object trajectory measurements. We present implemented scenarios (parallel or serial) for the layout of two radars in a distributed measurement system based on X-band mobile radars. Mobile radars for remote registration of small airborne object movement parameters are build according to the cascaded active phased waveguide-slot antenna array technology. We discuss the main technical characteristics of radars in a distributed measurement/registration system, determining the limitations on the measurement distance and angular coverage.
1 citations
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TL;DR: The origin of the names of quasi-orthogonal matrix families and the connection of their orders with known numerical sequences are described and examples of the applicability of the matrices for various tasks of information transformation and processing are given.
Abstract: The evolution of knowledge about quasi-orthogonal matrices as a generalization of Hadamard matrices is briefly considered in the paper. We describe the origin of the names of quasi-orthogonal matrix families and the connection of their orders with known numerical sequences. The structured matrices, searching for which is of the greatest practical interest, are distinguished: symmetric, persymmetric, cyclic, structured according to Walsh. There are also features and characteristics of such matrices highlighted in the paper. Examples of the applicability of the matrices for various tasks of information transformation and processing are given: noise immune coding, masking, compression, signal coding.
1 citations
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TL;DR: This work shows the results of the study of aperiodic autocorrelation functions of new code sequences based on persymmetric quasi-orthogonal circulants, aimed at stimulating scientific interest in new bases derived from quasi- Orthogonal matrices, as a basis for the revision of signal coding algorithms.
Abstract: For radar and communication systems, the search for code sequences with good correlation properties remains one of important tasks. This work shows the results of the study of aperiodic autocorrelation functions of new code sequences based on persymmetric quasi-orthogonal circulants. The numerical values of the quality parameters such as: the maximum sidelobe level, integrated sidelobe level ratio, and merit factor are given. Applying new code sequences makes it possible to reduce the maximum sidelobe level of the aperiodic autocorrelation function, as well as to reduce the summary energy of the sidelobes, which makes it possible to conclude that their application is promising. The obtained results are aimed at stimulating scientific interest in new bases derived from quasi-orthogonal matrices, as a basis for the revision of signal coding algorithms.
1 citations
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18 Apr 2021
TL;DR: 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.
Abstract: 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.
1 citations
References
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TL;DR: It has been found out that the characteristics of autocorrelation functions for Mersenne codes 3, 7 and 11 exceed those for Barker codes, which is a basis for ensuring greater noise immunity of probing signals in radar channels and for increasing the probability of their correct detection.
Abstract: Introduction: Barker codes representing binary sequences (codes) of finite lengths 2, 3, 4, 5, 7, 11 and 13 are widely used in solving the problem of increasing the noise immunity of radar channels. However, the code sequences for n > 13 are unknown. Sequences derived from quasi-orthogonal Mersenne matrices also have not been used for these purposes.Purpose: Studying the ways to compress a complex modulated signal by Mersenne sequences obtained from the first rows of a monocyclic quasi-orthogonal Mersenne matrix, as an alternative to Barker codes.Results:It has been found out that the characteristics of autocorrelation functions for Mersenne codes 3, 7 and 11 exceed those for Barker codes. This is a basis for ensuring greater noise immunity of probing signals in radar channels, as well as for increasing the probability of their correct detection, proving the expediency of their application for amplitude and phase modulation of radio signals.Practical relevance:The obtained results allow you to increase the compression characteristics in radar systems when solving the problem of detecting targets under noise and interference. The wide application of Barker codes of length 3, 7 and 11 in digital data transmission systems provides a special interest in similar Mersenne codes when implementing noise-resistant data transmission in radio channels in a complex electromagnetic environment. Discussion: An unresolved problem is the non-symmetry of elements in a coding Mersenne sequence. This problem can be solved either by special synthesis of a phase-modulated signal or by finding new approaches to their compression.
12 citations
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TL;DR: Three practical schemes for digital detectors of bursts of ultra-wideband signals are presented and analytical expressions for calculating their performance are provided.
Abstract: Ultra-wideband (further UWB) signals are increasingly being used in communication systems. The paper presents three practical schemes for digital detectors of bursts of ultra-wideband signals and provides analytical expressions for calculating their performance.
8 citations