Research On The Performance Of High-dynamic Spread Spectrum Synchronization System

Spread Spectrum Measurement and Control System, is now an often-used communication system in remote control system. Because the high-dynamic caused by aircraft’s high-speed flight relative to the ground,which will lead to significant changes in frequency offset and rate of frequency offset and make the spread spectrum signal synchronization to be very difficult. Using the traditional method of synchronization, it will lead to long synchronization time and great bit error rate. Therefore, the design of carrier synchronization structure in spread spectrum system is essential.This paper firstly introduces the basic principles of spread spectrum technology and basic concepts of high dynamic. In the third chapter, the paper lists several common acquisition methods in spread coarse synchronization and focus on the theoretical explanation of system architecture of FFT-based acquisition methods and takes theoretical analysis and simulation on spread spectrum signal acquisition performance under high-dynamic,and gives design basis of the relevant parameters(pseudo code correlation integral length, frequency search step unit) of spread spectrum signal acquisition structure.In the fourth chapter, the paper lists several common tracking method in spread fine synchronization and has theoretical analysis and simulation on spread spectrum signal carrier tracking’s key issues(including the identification algorithm, loop filter, etc.) and has simulation on tracking performance of spread spectrum signal under high dynamic.According to the research results of the third and fourth chapters, this paper then gives the spread spectrum synchronization system, identification algorithm and related parameters in this project. As for spread spectrum signal capture, this paper adopt the acquisition method using FFT spectrum analysis parallel search method which converts the two-dimensional acquisition process of carrier frequency and pseudo-code phase to one-dimensional process and achieve the purpose of shortening the acquisition time. As for spread spectrum signal tracking, this paper adopt a carrier tracking structure with frequency-locked loop guiding Phase-locked loop and use an improved phase detector algorithm and cross product automatic frequency tracking algorithm and gives system performance simulation of the spread spectrum synchronization system under high dynamic simulation. The simulation results show that the performance of spread spectrum synchronization structure proposed in this paper can satisfy the spread spectrum communication index under high-dynamic triggered by spacecraft flying.