Study Of The Method For Precise Determination Of The Transducer Transient Elevation Datum In GNSS Singal Blind Area Under The Cross Sea Bridge

The number of cross-sea bridges in China is increasing,bridge piers and the deformation of the seabed sediment around the bridge is the important factor affecting the safety of the bridge.But in the process of monitoring,due to the bridge block,shipborne GNSS receiver signal in the bridge area navigation accuracy is poor and can not navigate the vessel;and the cross-sea bridge is located in the complex area of tidal change in the strait or the bay,and the span of the bridge is long,it is difficult to obtain real-time high-resolution precision tide near survey ship.The above two reasons result in poor multi-beam acoustic emission instantaneous elevation reference accuracy.In order to solve the above problems,this paper based on the dual ship model shipborne combination system to determine the GNSS signal blind zone transducer instantaneous elevation benchmark and carry out the following research:1)Explain the composition and working principle of the model based on the two-ship model(No.1 for survey,No.2 for GNSS tide level),detailing the characteristics of the composite system.Based on the GNSS tide data determination method on the No.2 ship,the instantaneous tide level of the No.1 surveying ship is provided to solve the problem that the precisely existing tide level can not be obtained in the GNSS signal blind spot.2)Detailing the importance of time synchronization for multi-sensor systems.Using UTC time as a benchmark,GNSS with gesture sensor time are synchronized based on the multi-source signal vertical feature matching;matching GNSS and gesture data over time based on spline interpolation function;according to the interpolation extrapolation method,the pressure sensor draft data and the GNSS time are matched,the multi-sensor time synchronization problem is effectively solved and the double-boat mode measurement accuracy is improved.3)The effect of spatial data processing on the instantaneous elevation accuracy of GNSS signal blind zone transducer is carefully analyzed.Aiming at each data processing link to carry out:GNSS elevation signal quality control,sensor draft correction based on the shipborne pressure,sensor attitude correction based on the shipborne attitude and tide level determination based on fast fourier transform.On the basis of the above spatial data fusion,the cross-sea bridge under the GNSS signal blind zone transducer instantaneous elevation accurate data can be achieved.4)Experiments on accurate determination of instantaneous elevation of GNSS signal blind transducers has been carried out in Shenzhen Bay,Guangdong Province.The effectiveness of the method for determining the instantaneous elevation datum of GNSS signal blind zone transversal bridge is verified by comparing and evaluating the elevation of the experimental area.