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Based on postprocessor GPS PPK technology, we carried out the research on long-distance tide observation and extraction, the determination of vertical datum and the construction of vertical-datum transformation model. A model for calculating a height series for instantaneous water surface was researched, meanwhile, the best cut-off periods for tidal extraction for anchored and on-the-fly status are proposed. Finally, based on long-term anchor PPK and tide-gauge tidal levels for different situations, a determination of MSL and chart datum as well as the models for calculating their geodetic heights were investigated and proposed. A method to establish a seamless chart datum geodetic height model is presented. An test project showed that the accuracy of GPS tide level reference to chart datum measurement method as presented in paper can be better than 10 cm when the GPS baseline is less than 100 km. [ABSTRACT FROM AUTHOR]

For mitigating the impact of outliers in measurements and background map, a new method for underwater terrain matching navigation, base on robust statistics theory is proposed in this paper. By applying the M estimation theory, the robustness of the algorithm is improved. Experiments proved the good performance of the method. [ABSTRACT FROM AUTHOR]

The determination precision of temporary tidal gauge's chart datum is influenced by tidal nature similarity, datum transfer distance and topographical environment characteristics. This paper has studied the relationship between precision and influencing factors, and specific precision functional models in south and north branches of Yangtze River Estuary have been given respectively, through a large number of chart datum transfer tests with using tidal gauges' data in the Yangtze River estuary. The tests results indicate that the chart datum transfer precision in the south branch can be superior to 8 cm, when the difference of tidal type is less than 0. 05 and transfer distance is less than 80 kilometers. While, the precision is 20 cm in the north branch when the distance no less than 40 km. The research achievement has an important significance to the determination precision of chart datum transfer in the Yangtze River estuary. [ABSTRACT FROM AUTHOR]