Two High-Precision Ultrashort Baseline Location Methods Based on Phase Difference

Abstract

In this paper, two ultra-short baseline location methods for underwater broadband signal are proposed. In order to improve the positioning accuracy of acoustic positioning, the coarse time delay is measured by parabolic interpolation of cross-correlation results. According to the coarse time delay, the ambiguity number of the phase at the cross-correlation peak is solved and the ambiguity is solved twice, so as to obtain the high-precision time delay difference and improve the positioning accuracy. This method is suitable for the case without near body multipath. Aiming at the near body multipath problem, its influence on ambiguity resolution and positioning accuracy is analyzed. Based on the coarse time delay, adjusting time delay and the Fourier transform of cross-power spectrum phase joint method is proposed to further improve the accuracy of coarse time delay, so as to improve the accuracy of ambiguity resolution. On this basis, the location information feedback and real-time attitude information are used to estimate the coarse time delay difference, and the ambiguity number is further constrained to further improve the accuracy of ambiguity resolution. In order to reduce the influence of multipath on the phase and improve the positioning accuracy, a Kaiser window is added to the source and the phase difference is changed to the phase difference at the first point of threshold. Numerical simulation and field test demonstrate that the first algorithm proposed in this paper improves the positioning accuracy and the accuracy of ambiguity resolution. The second algorithm improves the accuracy of ambiguity resolution and positioning accuracy in the presence of near body multipath.