Modeling and analysis of accuracy of algorithms of low frequency beamforming in shallow sea

Abstract

The use of spatial processing of low-frequency hydroacoustic signals in the shallow sea gives direction finding errors associated with the multimode nature of the propagation of hydroacoustic signals. To reduce direction finding errors, it is necessary to use noise direction finding algorithms that are matched with waveguide. Due to the complexity of their implementation, adaptive or quasi-optimal algorithms are used in practice. However, with a large dispersion of the phase velocities of normal waves and a receiving antenna with low resolution, the efficiency of the algorithms decreases. The article contains modeling of several well-known noise direction finding algorithms, including matched-field processing. The dependence of the accuracy of bearing in the application of different algorithms on the ability of the hydroacoustic system to resolve normal waves was investigated. It is shown that their resolution depends on the interference period, antenna length and initial phases of normal waves. Formulas and relations allowing to estimate the magnitude of the bearing determination error are given. The simulation of the hydroacoustic system with specific parameters is carried out. The parameters of the waveguide were set close to real. The mean value and the mean square deviation of the direction finding errors and the probability of false detection of the sound source were calculated.