Research On Combined Orbit Determination Method For Navigation Constellation Using Intersatellite And Ground-based Measurements

Precise orbit determination(POD)for navigation satellite constellation plays a very important role in supporting high precision navigation,positioning and timing service of GNSS.Because it's not possible to build ground stations worldwide,the traditional OD method,which uses measurements collected by ground-based tracking stations only,can't meet the requirement of BeiDou System(BDS)for global service.In 2015,new generation of Ka band Inter Satellite Link(ISL),designed and developed by our country independently,had been in operation onboard the satellites,which provides important technical support for global observation of BDS,and this makes combined orbit determination(COD)become research hotspot.Based on this background,this paper focuses on COD for BDS supported by regional distribution stations and ISL,analyses measuring performance of the new generation ISL,and discusses the COD method and some influence factors for COD improvement.The main researches are as follows:(1)Establishes the COD model.Researches the basic principles and the algorithm flow of COD using batch processing algorithm;summaries the methods and indexes for COD result evaluation;simulates mix satellite constellation based on BDS to verify the COD method.(2)Analyses measuring performance of the current Ka ISL of BDS.Researches pre-process for Ka ISL data starting from principles of Ka ISL Dual One Way Ranging(DOWR);the internal accuracy of Ka ISL data is obtained by residual analysis method;the external accuracy of Ka ISL data is obtained by using Satellite Laser Ranging(SLR)data as an external check.(3)Analyses the influence of measurement error and distribution of ground stations for COD.As for the coarse data and the difference of intersatellite data and ground-based data,the eliminating method for coarse data and weighting method for different data are researched together with their influence on COD precision;As for the number and distribution of ground stations,several different cases and their influence on COD precision are also discussed.Researches in this paper used both true data and simulated data to realizing COD for GNSS constellation.Results show that,the accuracy of Ka ISL reaches centimeter degree,and it can provide powerful support for high precision COD for BDS under regional station distribution.This paper verifies some related performance of ISL technologies,and provides reference to future application of ISL.