Research On Key Technology In The Tidal Level Extraction System Based On GNSS Technology

Tidal data is essential reference for people who engaged in maritime activities and tidal level measuring is an important tool of acquiring tidal level information. The traditional measuring methods are used to obtain tidal level through setting up tide station, interpolating the tide model or throwing a gauge. The traditional tide methods have some shortcomings, such as that the tide station needs to be fixed, the precision of interpolating the tide model is low and throwing a gauge may have the risk of blank or missing data. The tidal observation method based on GNSS technology can obtain the tidal level at the position of the survey boat. This method makes up for the deficiency of the traditional method and enrichs the existing methods of tidal observation method.This paper carries out the following research on the basis of analyzing domestic and foreign research.(1)The system of tidal level measurement based on GNSS technology. This paper design the system of tidal level measurement based on GNSS technology and introduce the constitution and principle of the system. A feasible method is proposed to measure real time dynamic draft of survey boat through the pressure sensor. This method solves the problem of low dynamic draft sparked off by inaccurate empirical formula and improved the existing method.(2)Data processing of water extraction system based on GNSS technology. Data processing is the key of obtaining the final tide level. The method of temporal registration using different time standards is studied in each link of data processing. The method of elevation data control based on the idea of Heave, elevation datum transformation, hull attitude correction model, tidal level extraction through low pass filter and device model are studied. The final tidal level data is obtained on the basis of the above research.The software of tide level extraction based on GNSS for coastal waterway is developed on the basis of the above research.(3)The data processing using the existing tide level extracting method based on GNSS technology does not take the effect of time delay of multisensory into consideration. In fact, time-delay exists objectively and has effects on the precision of tide level extraction. In order to solve this problem, time synchronization method of multisensory based on similarity matching of vertical signal. This method can accurately detect the time-delay of multisensory and solve the problem that time is not synchronized, improve the precision of tide level extraction.(4)In order to verify the effectiveness of the method in this paper, measurement experiment for water level measurement based on GNSS is carried out in the sea channel of Guang Dong, Ya men. The experimental results show that the extraction tidal level using the method proposed by this paper is in keep with the tide level of manual measurement. The feasibility and reliability of the algorithm proposed in this paper is proved.