Development And Accuracy Analysis Of Tide Free Measurement System Based On Network RTK

Compared with the traditional methods of measuring the depth of the water,the use of GNSS RTK has all-weather and is not affected by the location of the tidal station.This technology not only is not affected by the tide station location and do not need manual operation of gauge observation,but also could avoid the draft,wave effect on the measurement data.This paper systematically elaborates the positioning principle of conventional RTK and network RTK,and focuses on the principle,system construction and error impact analysis of non-tidal depth measurement based on GNSS RTK.The engineering practice and system improvement have been carried out in the Nanjing section of the Yangtze River.The practical results show that the network-based RTK non-tidal water depth measurement system can meet the accuracy requirements of waterway engineering surveys.The main research contents and conclusions of this article are as follows:First of all,the principle of no tide measurement based on RTK is deeply studied.From the comparison of data acquisition methods,we recommend a comprehensive data collection technology based on JSCORS system,which can ensure data to be comprehensive and effective.Then from the underwater topographic measurement system,the method of no tide measurement is analyzed and the calculation model is given.Then the reason from the data acquisition environment influence factors of measurement error,mainly on the transducer installation,velocity,delay effect,speed,attitude of ship,ship type,weather factors,elevation datum conversion measurement error factors existing in inland waterway.According to the analysis of each influence factor,the solution is given,and the related calculation model is given to improve the accuracy of data measurement.After the data acquisition,the correction method of influencing factors is processed from the data processing in the system.Finally,the accurate measurement data can be obtained from the improved calculation model from the no tide depth measurement system.Through the test data and the verifying of the essence of the geoid and the accuracy verification of the underwater topographic survey,the method of removing the rough difference by the trend surface filtering is proposed.These methods effectively reduce the influence factors of the error,and make the measured data less than 5cm,and can be applied to the inland river channel measurement well.