Study Of Leo Orbit Determination

More and more LEO are launched as widely applied to economy, military affairs, scientific research and so on. These satellites have different missions and make a contribution to national economy. In order to accomplish their missions, Precise orbit determination (POD) is the base and precondition, and therefore is a attentional problem for people.The researchful object of this thesis is LEO satellite. First, this thesis analyses the basic theories of POD, including time and coordinate systems, force model, linearization of observation equation, calculation of parameters and evaluation of orbit. Then, it discusses different observation technologies and observation equation of onboard GPS and SLR. In succession, it introduces software and methods of POD, and researches the factors that affect orbital precision based on the simulation of data onboard GPS observations. At last, the orbit determination of LEO uses methods of onboard GPS POD and SLR POD, and the data is CHAMP, GRACE A/B's onboard GPS real data and Jason-1's SLR real data. The precision of the results is good.This thesis's main works include as follows:1. The basic theories of orbit determination is analysed in this article. It introduces time and coordinate systems, different models of perturbing force, methods of observation technologies, linearization of observation equation, calculation of parameters. At the same time, it analyses the mothods of orbital evaluation, SLR orbital evaluation, and software of CASMORD and methods of orbit determination.2. The factors that affect orbital precision are analysed in this article. The factors include error of numerical calculation, observational error of P code and phase, altitude angle, antenna phase center offsets, jump and error, gravitation, ocean tide and so on.3. Orbit determination of onboard GPS and SLR. The results of GPS orbit determination using CHAMP and GRACE A/B's onboard GPS real data are 11.39cm and 7cm separately, and the result of SLR orbit determination using Jason-1's SLR real data is 20.67cm.