Точность оценки пеленга источника радиоизлучения при нерегулярной структуре спектра в полосе анализа пассивной системы местоопределения
This paper deals with the angle-of-arrival passive location system consisting of mutually coherent circular antenna arrays implementing one-step maximum likelihood based estimation procedure. The question raised in the present paper is accuracy degradation due to the arbitrary positions of spectral components in the locator receiver bandwidth in comparison with Cramer-Rao Lower Bound for the case of Gaussian random radio emission. The well-known expression of angle estimator accuracy in the case of band-uniform spectrum is compared to the results obtained by the numerical statistical modeling; this allows one to evaluate the deterioration of the accuracy due to arbitrary positioned spectral components. The numerical modeling also provides the discussion for preliminary time-window filtration of the received signals in order to increase the accuracy of angle estimator. Thus it was shown that the common used windows such as Hann, Bartlett and Keiser-Bessel can be useful in the case of sparse arbitrary spectrum.
This paper introduces an approach for implementing maximum likelihood parameter estimators using feedforward artificial neural network of multilayer perceptron architecture. A theoretical foundation of the proposed approach is presented in the assumption that the model of observation is known as well as the values of its vector of parameters. For a practical example the implementation of direction of arrival estimator for the active ring antenna array is shown. In order to estimate a performance and accuracy of the proposed approach, the results of numerical calculation are presented, compared to the algorithm based on optimal numerical solution and referenced to Cramer–Rao lower bound. The results also indicate that there is no significant dependency of the accuracy of estimation on actual parameter value. Moreover, the calculations take significantly less time, although some of it is spent on the initial training of the neural network.
Generalized error-locating codes are discussed. An algorithm for calculation of the upper bound of the probability of erroneous decoding for known code parameters and the input error probability is given. Based on this algorithm, an algorithm for selection of the code parameters for a specified design and input and output error probabilities is constructed. The lower bound of the probability of erroneous decoding is given. Examples of the dependence of the probability of erroneous decoding on the input error probability are given and the behavior of the obtained curves is explained.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.