Ecological Systems and Devices Annotation << Back DETERMINATION OF THE OPTIMAL AVERAGE SEARCH FREQUENCY OF A PASSIVE NONLINEAR HYDROACOUSTIC MARKER-REFLECTOR Ya.V. Feshchenko Currently underwater markers are used in various fields: in navigation and positioning systems, in marine research, in the defense sector, in diving equipment, underwater archaeology, etc. The purpose of their use is to determine the location of underwater objects. The analysis of existing markers showed the impossibility of their universal and effective use for solving these tasks due to the presence of significant disadvantages, such as: limited service life; undisclosed operating mode, high cost and complexity in production; unsafe for the environment. In order to create a device capable of solving these shortcomings, a formula was mathematically derived for the dependence of the optimal frequency of the sonar sounding signal on the distance to the passive nonlinear marker, taking into account losses in the aquatic environment. For this purpose, a mathematical model of the signal formation process was investigated. The full equation of the magnitude of the received signal from the hydroacoustic marker-reflector, which ensures its detection by search sonar, was considered. Due to the unavoidable gap of the first kind due to the presence of two different empirical formulas for fi nding the attenuation coefficient for different frequencies, dependencies were derived for three different cases, and a general algorithm for finding the optimal frequency for specifi c values of the conversion coefficient and the distance between the sonar and the nonlinear marker-refl ector was described. On the basis of the obtained formulas, dependency graphs were constructed, which showed that the required range and aperture sizes of hydroacoustic antennas have the greatest influence on the value of the signal power flux density. Keywords: Hydroacoustics, nonlinear effect, attenuation coefficient, optimal frequency. DOI: 10.25791/esip.8.2023.1388 Pp. 03-11.