Configuration Design and Positioning Capability Assessment of Seafloor Geodetic Network

Seafloor geodetic network (SGN) with a set of geodetic stations deployed on the seafloor is an indispensable part of the global geodetic reference frame for crustal deformation monitoring and marine disaster warning, which may provide the surface and submarine users with positioning, navigation and timing (PNT) information by forming a positioning array system like the GNSS constellation (Yang Y. et al, 2020). The establishment and maintenance of SGN is the premise for its contribution to the global geodesy development and marine science research. Contrast to the terrestrial geodetic network construction, SGN establishment faces more challenging obstacles in energy supply, communication capability etc. The seafloor infrastructure construction is costly and therefore conducting the configuration design and assessment for SGN is necessary with regard to the limitation of the station number.

Since SGN consists of multiple stations equipped with acoustic signal transponders (tp), the inter-station baseline measurements are available. These inter-station ranging measurements typically have higher accuracy and are expected to assist in high-accuracy locations for SGN establishment. Therefore, in this work, the inter-station ranging strategy is taken into account in configuration design for SGN. According to the acoustic ray bending principle, we present the maximum tolerant distance between stations to avoid interference by the seafloor. The simulations show the transmission loss and ray-tracing tracks of the acoustic signals from the transponders corresponding to different transmission distances based on the Bellhop model. With the reference of the aforementioned inter-station tolerant distance, we design five-tp and six-tp array configurations for SGN. And then we adopt the position dilution of precision (PDOP) criteria to simulatively evaluate the positioning capability of SGN, in which takes the automatic underwater vehicles (AUV) application for example since AUVs are tended to be utilized to monitor ocean environment and seafloor properties in details. In the presentation, we will show the simulation results of SGN design and assessment for AUV navigation & positioning.