Vol 59, No 9 (2016)

This is the second paper in a series of papers dedicated to the peculiarities of estimation of the continuous energy spectra of random processes of different nature, which are determined by their samples at discrete moments of time. In this paper we analyze extreme performance of the reconstruction of continuous energy spectra, in particular, the ones of interperiod fluctuations of reflections from meteorological objects in pulse Doppler weather radars under the hypothetical conditions of a priori known covariance matrix of the analyzed processes. The reasons, which cause known disadvantages of classical (nonparametric) spectral estimation (SE) methods for energy spectrums shape reconstruction, are discussed. We have considered known and suggested criteria, using which the extreme performance of classical SE methods and parametric superresolution ones has been quantitatively compared. It has been demonstrated that the extreme performance of SE methods contains important but not comprehensive information. In order to choose a SE method appropriate for operation under real-world conditions, this information should be used together with information on a corresponding method’s adaptive performance under a priori unknown statistical characteristics of input effects.

Thetheoretical model of pulse ultrawideband (UWB) receiving antenna consisting of a ferrite element surrounded by a coil of conductor is investigated. The magnetodielectric cylinder of infinite length is selected as the ferrite element. The excitationUWBsignal represents a pulse of electromagnetic field with the envelope in the form of a Gaussian function with high-frequency filling signal. The peculiarities of amplitude-time dependence have been considered for the pulse of induction electromotive force occurring in the closed conducting loop, which surrounds the cylinder, under the assumption of absence of its influence on the scattered fields inside and outside the cylinder. The connection between the electromagnetic parameters of the ferrite element and the frequency-time parameters of the excitation pulse electromagnetic field, which are optimal from the point of view of effective undistorted signal reception, has been determined.

An algorithm for the digital generation of broadband chaotic signal with comb-shaped spectrum has been developed on the basis of nonlinear discrete system with delay. The data transmission method using the spectral manipulation technique with digital generation and processing was experimentally implemented. The results obtained can be utilized in the systems of transmitted data security from unauthorized access.