Measurement Error Modeling and Parameters Estimation Algorithm in LEO Combined Orbit Determination Based on Bi-satellite Positioning System

Measurement error modeling and parameters estimation are very important for heightening low earth orbit (LEO) combined orbit determination (COD) precision based on bi-satellite positioning system (BPS). This paper analyzes system error and stochastic error characteristics of COD range-sum observation data, and designs range-sum observation models based on constant system error, nonlinear reduced parameters fitting system error and corresponding trajectory and system error parameters estimation algorithm. And then the paper constructs stochastic error parameters estimation algorithm based on autoregressive moving average (ARMA) models, and finally carries about simulation experiments according to different simulation circumstances. Simulation computation results show that we can gain more precise estimation for trajectory parameters and system error parameters by system error modeling and statistical characteristics analyses of stochastic error, especially can fitting LEO COD observation system error commendably by making using of reduced parameters fitting model, which heightens trajectory parameters estimation precision.