Research On Codeless Doppler Orbit Determination Based On Navigation Satellites Signal

The determination of satellite orbit parameters is the foundation of satellite application. With the rapid development of space technology, the requirements of real-time, autonomous, precision and reliability of the satellite orbit determination are also increasing. At the same time, the satellite autonomous orbit determination that is the development trend of future has attracted people's attention with the increase of the number of satellites and the need of space security. So, this paper puts forward an orbit determination method of codeless Doppler orbit determination based on navigation satellites signal. Main contents are as follows:In order to ensure the measurement accuracy of the carrier Doppler of navigation satellites signal,firstly, the structure of the satellite navigation signal is analyzed, and derives the process of navigation signals down-conversion and remove code. Then present a method based on phase compensation and data block accumulation estimate the carrier frequency accurately; the next, expounds the principle of codeless carrier tracking loop and analysis the effect of Doppler in the high dynamic environment on the performance of the tracking loop; the isolation and isolation frequency are proposed to reduce the influence of the close carrier frequency on the tracking results, and the selection principle of the loop orders and parameters are analyzed. Then obtain carrier frequency accurately through the phase differential precision. Finally, the simulation results show that the initial value estimation of the carrier frequency can meet the bandwidth requirement of tracking loop, and the accuracy of loops can meets the demand of orbit determination.For navigation satellite identification, this paper proposes a method based on the characteristics of Doppler: the measurement of the Doppler can be obtained by tracking loop, and the empirical values are calculated by the initial orbit parameters and the ephemeris of navigation satellites. Take the two-group values correspondence as a criterion, and research on match algorithm based on trichotomy and dichotomy to estimate clock-error quickly. Establish the match index with easy and low matching error rate, adopt the ‘global match, local elimination' strategies to improve the reliability of satellite recognition. The simulation shows that the new technology is feasible and has a certain degree of recognition.In the high precision orbit determination, status equation is set up according to the motion model of the satellite orbit equation and observation equation is established based on the Doppler measurement system. Design the EKF filter to estimate of the LEO satellite orbit parameters. Thesimulation analysis the impact of the initial orbit error, and the number of navigation satellites and the accuracy of Doppler to results. In order to verify the main algorithm of orbit determination are presented in the paper, a semi-physical simulation experiment platform is built.The satellite orbit determination algorithm in this paper provides a kind of technical ideas for achieving high accuracy, high reliability of orbit determination under the condition of pseudo code unknown.