Passive Localization of Underwater Broadband High-Frequency Targets Based on Frequency Difference Matching Field

High-frequency signals are susceptible to environmental uncertainties during propagation, leading to degraded localization performance when using traditional matching field methods. To address this issue, this paper proposed a passive localization method for high-frequency signals based on the frequency difference matching field. This method performed quadratic product processing on the received data of arrays at different frequencies within the high-frequency bandwidth, constructing a sound field structure at a difference frequency much lower than the original frequency. By applying the established localization algorithm based on the matching field at difference frequency, the high-frequency broadband signal was reduced to the low-frequency range for processing. Firstly, the principle of the frequency difference method was presented, and the grazing angle of multipath propagation in shallow water was estimated. On this basis, physical models for frequency difference matching fields suitable for shallow and deep-sea environments were proposed. Finally, simulation results show that the proposed method substantially outperforms traditional methods in terms of high-frequency signal localization in uncertain environments.