Radioelectronics and Communications Systems

Method for differentiating complex matrix functions in digital antenna array response models

2025-06-20T10:47:13+03:00

The paper proposes a method for differentiating the Khatri–Rao products of several matrix functions used in digital antenna array (DAA) response models, which are matrix expressions depending on the same vector of unknowns. The product of block matrices of values of amplitude-frequency responses (AFR) of several series-connected digital filters (quadrature I/Q demodulators, decimating filters, fast Fourier transform (FFT) filters, or so-called frequency filter banks, etc.), as well as the AFR of antenna elements or several stages of DAA receiver channels.

The procedure for the factorization of matrix derivatives of the specified type is considered. For compact notation of differentiation results, it is proposed to use matrix operations of block sum, column, and row diagonalization. For example, we present the results of differentiation of the Khatri–Rao products consisting of two and three matrices depending on one vector of variables, and the variants of factorization of such derivatives.

The proposed differentiation method is generalized to the case of a combination in one expression of different types of derivatives with respect to the block vector of the Khatri–Rao product, when the elements of not all, but several block matrices depend on the same block of unknowns.

The factorization procedure allows us to simplify the differentiation process and reduce calculations when forming the Fisher information matrix to analyze the potential accuracy of signal parameter estimation in DAA.

Nonparametric method for signal detection using SG statistics

2025-10-16T21:18:18+03:00

The paper proposes a new nonparametric method for signal detection based on Savit and Green (SG) statistics and signal observation processing using the surrogate data technology, namely Attractor Trajectory Surrogates (ATS) algorithm. The proposed detection method does not depend on a priori information about the interference probability distribution density and does not consider the model of the observed signal. Using the ATS algorithm allows us to reduce the noise in signal observation. The noise observation estimate has been obtained from the observation itself using the singular spectral analysis for the first time. A comparative analysis of the proposed nonparametric and classical signal detection methods using an energy receiver based on χ²-statistics has been performed. The simulation results showed an increase in the probability of signal detection using the SG statistics-based method for different signal-to-noise ratios compared to using an energy detector. It is also demonstrated that the proposed nonparametric detection method does not depend on the density of the interference probability distribution, using an example of interference with a logistic distribution. Recommendations are given for selecting the parameters of the proposed nonparametric detection method.

Improving performance of genetic algorithm in circuit optimization

2025-10-16T21:29:21+03:00

This work is devoted to optimizing electronic circuits by modifying the genetic algorithm (GA) based on the previously developed idea of generalized circuit optimization. In this case, it is possible to overcome one of the main disadvantages of GA, namely, premature convergence to local minima, and significantly improve the quality of minimization. In this case, the updated GA generates a set of populations determined by different generalized optimization strategies. A control vector introduced within the generalized optimization framework determines fitness functions and chromosome parameters, such as length and structure. The control vector specifies the number of independent variables of the optimization problem and is the main element for selecting the most promising optimization strategies. Complex strategies obtained by combining different basic strategies can improve the accuracy of the optimization problem and reduce the number of required generations. As a result, it is possible to improve the quality of the resulting solution and significantly reduce the computer time needed to optimize the electronic circuit.

Primary frequency properties of LPTV circuits

2025-10-16T21:37:56+03:00

The paper considers primary frequency properties of parametric LPTV (linear periodically time-varying) circuits in steady state under the action of a harmonic input signal and periodic changes of parametric elements. Based on the representation of the transfer function by a finite Fourier series, an analytical expression for the output signal of a parametric circuit has been obtained. The conditions for the coincidence of pair harmonic components forming characteristic frequencies with amplification or attenuation effects have been investigated. A method for determining such frequencies has been proposed, and examples of its application in a synchronous detector, frequency converter, modulator, and in single-loop and dual-loop parametric amplifiers have been presented. The results obtained can be used to design radioelectronic devices with due regard for the parametric effects.

Application of Thevenin-Barbi circuit equivalent for optimization of energy characteristics of DC electrical circuits

2025-10-16T21:47:03+03:00

The paper demonstrates the advantages of using the Thevenin–Barbi three-element circuit equivalent in energy studies of DC circuits. The optimal and limiting values of the load parameters of the Thevenin–Barbi circuit equivalent at a given range of the efficiency changes are determined, which allows us to study the energy characteristics of complex DC electrical circuits using a simplified model. For the first time, mutually unambiguous correspondences between the parameters of the Thevenin–Barbi circuit equivalent and the primary parameters of a passive linear four-pole network and a homogeneous long DC transmission line have been established, which allowed the results obtained for the optimization of the equivalent’s energy characteristics to be extended to them. The data of the computer simulation confirmed the adequacy of the proposed method for calculating the distributed parameters of the DC transmission line with the specified energy characteristics based on its Thevenin–Barbi circuit equivalent.