Passive ranging method for shallow water based on dual depth Warping transform information fusion

In shallow-water environments, to address the issue of multi-value in estimating the distance of a sound source using the autocorrelation function Warping transform of single-depth receiver signal, a method of dual-depth Warping transform information fusion is proposed for distance measurement. This method integrates the Warping transform extraction results from the dual-depth measurement field with depth-differentiated eigenfunction information derived from the copy field, enabling the identification of the order of the normal modal interference terms, consequently enhancing the accuracy of distance measurement. Additionally, there is another need in accurately extracting the characteristic peak positions of the Warping transform in actual marine environments. In this study, the frequency invariance of Warping transform is jointly applied with image morphology to strengthen the characteristic frequency structure, thereby enhancing the robustness of ranging algorithm. The real-data experiments show that the ranging results align well with the ground truth, indicating that the proposed passive ranging method is feasible for practical application.