Структура пассивной радиолокационной системы для определения местоположения летательного аппарата при заходе на посадку
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.
The algorithm for searching the global maximum of the objective function for increasing the speed of operation of a one-stage algorithm for estimating the location of the radio source of a passive distributed wide-band radar system is developed and investigated. The problem is solved by the transition from the universal gradient method of searching for a global maximum to a search of the values of functions over a sufficiently dense grid in the search domain and further refinement by the methods of searching for a local extremum. The condition for choosing the minimum sufficient step of discretization of space is formulated and three strategies for choosing a step are proposed: homogeneous, heterogeneous and adaptive. Estimates of the gain in run-time and the frequency of occurrence of anomalous errors are given.
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.