# Implementation of Method of Minimizing the Side Lobe Level of Autocorrelation Functions of Signals With Nonlinear Frequency Modulation

## Keywords:

nonlinear frequency modulation, autocorrelation function, minimization the side lobes level## Abstract

An important problem that is solved during the creation of new and modernization of existing radar equipment is to ensure the maximum range of detection of air targets, which requires increasing the radiated power while maintaining the required range resolution. Since the generating devices, which are now widely used as semiconductor elements, have limited peak power, the required energy is emitted by increasing the duration of the sensing radio pulse, and the requirements for resolution are met by using so-called complex signals, the product of the spectrum width of which and their duration (signal base) is greater than one.

One of the types of complex signals is multifragment signals with nonlinear frequency modulation, which, unlike the well-known linear frequency modulated signals, have a significantly lower peak side lobes level of autocorrelation functions, but the value of this level depends significantly on the frequency and time parameters of the signal. Finding parameters that minimize the side lobes level of the autocorrelation function of nonlinear frequency modulated signals, which include fragments with linear frequency modulation, is an important scientific and technical problem, the solution of which is the subject of this article. The peculiarity of considering this issue is that, in contrast to the previously proposed implementation of the method of minimizing the side lobes level for mathematical models with a current time change, the paper develops models of shifted time, that is, when the time count of each subsequent signal fragment is shifted to zero. The first section of the paper analyzes the known publications, which shows that the method of minimizing the side lobes level of correlation functions has not been considered before for mathematical models of the shifted. Given this circumstance, the second section of the paper formulates the research objectives. The theoretical justification of a new variant of the proposed method by developing mathematical time-shifted models for two- and three-fragment nonlinear frequency-modulated signals, as well as the modeling results, are presented in Section 3. In further research, it is planned to develop an algorithm for optimizing the time-frequency parameters of signals with nonlinear frequency modulation based on mathematical models of current and shifted time.

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*Visnyk NTUU KPI Seriia - Radiotekhnika Radioaparatobuduvannia*, (95), pp. 16-22. Available at: https://radap.kpi.ua/radiotechnique/article/view/1976 (Accessed: 15September2024).

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Copyright (c) 2024 Олександр Костиря, Андрій Гризо, Ірина Хижняк, Андрій Федоров , Андрій Лук'янчиков

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