Research Of Carrier Synchronization Technique For Low SNR And High Dynamic In Satellite Communications

Beidou positioning system is researched and developed by own country. In the Beidou positioning system, the synchronization of spreading code and synchronization of carrier is the important technology which can affect the performance of the whole system. The technology of carrier synchronization is combined by the carrier capture and tracking. Carrier synchronization in low SNR and high dynamic condition is the foundation for the satellite communication.This paper analyzes and compares the internal and external researches of carrier synchronization, and researches the problem from a new point of view.First, the paper simply introduces the composition of the Beidou navigation system, working principle and characteristics. Highlights one of the carrier synchronization module, working principle, as well as the structure of phase-locked loop, phase model, works.Then, in the traditional carrier synchronization has been studied, Frequency discrimination of existing analysis and comparison of algorithms. a new frequency discriminator algorithm is proposed based on Discrete Fourier Transform in the overlap of automatic frequency tracking loop. The AR model bispectrum estimation is intruducted in the design, By increasing the time-domain extraction unit, the carrier tracking module's anti-noise performance is improved The components and overall system is simulated in MATLAB. The system is proved to be able to actualize carrier synchronization at low SNR and high dynamic conditions..Finally, by improve the right frequency discriminator algorithm. it further improve the system's anti-noise performance to meet the deep space communications at the same bandwidth. By MATLAB simulation proved that the improved system can implement carrier synchronization at lower signal to noise ratio condition.