Study On 0-1 Data Preprocessing Of Gravity Gradient Measurement Satellite

One of the key tasks in the field of modern geodesy is to determine the model of the earth's gravity field with high precision and resolution.With the development of satellite gravity detection technology,low-orbit satellite gravity observation technology has become the focus of geodesy research because of its ability to obtain high precision and high resolution earth gravity field model.The GOCE satellite,launched in March 2009,is a low-orbit gravity satellite using the tracking technology and satellite gravity gradient measurement technology.The key loads carried by the satellite provide a large number of high-precision gravity gradient observations for the calculation of high-resolution and high-precision gravitational field model.Therefore,the fine processing of the key load observation data becomes an important link to recover the high-precision static earth gravity field model.In this paper,based on the GOCE satellite Level?1B data released by the European Space Agency(ESA),the data processing of China's gravity gradient survey satellite Level 0-Level 1B(L0-L1B)is systematically analyzed and studied.The refined pre-processing research of the key load gravity gradiometer and astrograph data was completed,and the technical scheme and algorithm module of the gravity gradient satellite L0-L1 B data processing process were preliminarily constructed.Under the background of the implementation and development of gravity gradient satellite during the 14 th Five-Year Plan period in China,the research work in this paper has direct scientific significance and application value,and can provide important data processing technical support for the pre-research and implementation of China's independent gravity satellite mission.The main research work and results of this article are as follows:(1)The mission,technical characteristics,internal structure of GOCE satellite and the classification of Gradient satellite data products are introduced in detail.The research progress of level 0-level 1b data processing for gravity gradient satellites at home and abroad is summarized.The GOCE satellite coordinate reference system is described in detail,and the transformation relation between different coordinate systems is given.Based on the basic theory of satellite gravity gradient measurement,the observation equation of gravity gradient measurement is derived in detail in combination with GOCE measured data.(2)The data processing flow of the gradiometer(control voltage-acceleration data)is systematically studied,including the pretreatment of the control voltage,the solution of the gain factor and the application of the transformation equation,and the calibration model of the accelerometer data is given.The results show that even if the overall difference/common mode acceleration data obtained has good accuracy,the error is small compared with the official difference data released by ESA,which is close to the measurement accuracy index of satellite design,and the whole voltage-acceleration calculation conversion process is feasible.(3)Because the angular velocity calculated by a single star sensor contains large noise,which will be transferred to other angular velocity components when the coordinate system is transformed,the weight matrix is constructed by analyzing the noise of each axis of the star sensor,and the optimal quaternion is calculated by combining solutions based on the attitude quaternion least square method.The calculation results show that the noise of the angular rate calculated by the combination of star sensors is obviously reduced compared with that of single star sensors,and the effect of angular rate error transmission in coordinate conversion is effectively suppressed.(4)For gradiometer,star sensor precision of angular velocity in high frequency,low frequency exist lower done in-depth research,based on Stummer angular rate,the wiener filtering method of restoration and reconstruction by gradient meter and star sensitive instrument of angular velocity distribution of different precision in high frequency weighting,in turn,the angular velocity together,and then have the highest precision angular rate.In this paper,the accuracy is verified by analyzing the trace of gravity gradient.Compared with the nominal method,the gravity gradient calculated with the recovered angular rate under the satellite measurement bandwidth has shown a significant improvement.(5)The theory and method of gravity gradient measurement are studied in depth,the simplified equation of gravity gradient calculation by differential acceleration is derived in detail,and the angular rate is separated from it to calculate the high precision gradient value.The calculation results show that the gradient value calculated by the gravity gradient equation is simple and fast compared with the 1b data released by ESA,and the overall gradient accuracy is higher,which is suitable for the rapid solution of the gravity gradient value.