The position of a seafloor geodetic station can be determined by combining Global Navigation Satellite System (GNSS) and acoustic technologies, called GNSS-acoustic positioning. The precision of GNSS-acoustic positioning, a technique that employs the distance intersection, is determined by the positioning geometry formed by the ship’s track lines with respect to the seafloor station and the errors in the measurements. In the context of a shallow sea trial, we studied three key techniques in GNSS-acoustic positioning: the optimal geometric configuration, differencing techniques for acoustic observations and depth constraints offered by pressure gauges. The results showed that the optimal geometric configuration is a circular track with a radius of $$ \sqrt 2 $$ 2 times the depth plus an overhead cross-track with a length of the circle diameter. Differenced observations can improve the horizontal positioning precision but will worsen the vertical positioning precision due to the change in the geometric configuration and the elimination of vertical information if the number of observations is limited. The proposed difference strategy, that is, applying a symmetric location difference operator to the circular track and an undifference operator to the cross-track, can effectively improve the horizontal precision and avoid vertical defects. By using relative depth observations from two pressure gauges as constraints, the vertical defects of GNSS-acoustic positioning can be improved, achieving a better vertical positioning precision. Applying the proposed methods to high-quality GNSS and acoustic observations, the positioning precision of a shallow seafloor geodetic station can be better than 2 cm.

中文翻译：

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通过优化船舶航迹线和观测组合改进 GNSS 声学定位

海底测地站的位置可以通过结合全球导航卫星系统 (GNSS) 和声学技术来确定，称为 GNSS 声学定位。GNSS 声学定位是一种采用距离交叉的技术，其精度由船舶航迹线相对于海底站形成的定位几何形状和测量误差决定。在浅海试验的背景下，我们研究了 GNSS 声学定位的三项关键技术：最佳几何配置、声学观测的差分技术和压力计提供的深度约束。结果表明，最佳几何配置为半径为$$ \sqrt 2 $$ 2 倍深度的圆形轨道加上长度为圆直径的架空交叉轨道。差分观测可以提高水平定位精度，但如果观测次数有限，则由于几何构型的变化和垂直信息的消除，会使垂直定位精度变差。所提出的差分策略，即对圆形轨迹应用对称位置差分算子，对交叉轨迹应用无差分算子，可以有效提高水平精度，避免垂直缺陷。通过使用两个压力计的相对深度观测作为约束，可以改善GNSS-声学定位的垂直缺陷，实现更好的垂直定位精度。将所提出的方法应用于高质量的 GNSS 和声学观测，