High Dynamic Direct Sequence Spread Spectrum Receiver Tracking Technology To Study And Achieve

Satellite navigation and Internet are both a gift from the U.S. Department of Defense. At present, satellite navigation has been widely used in various fields in china. However, our in-depth research of the core technology of satellite navigation is not enough, especially how to work in high dynamic complex environment.In the spread spectrum receiver, the carrier tracking is the most weak and critical loop, the premise of the receiver can work, can quickly locate. Domestic and foreign scholars have proposed many solutions, but most only stay in the theoretical stage, due to technical limitations of existing hardware, many algorithm can not real-time compute, so in practical engineering applications are not often applied.This paper studies the tracking loop of spread spectrum receiver in the case of high dynamic condition. I first analyze the principle of spread spectrum signal generation and signal characteristics, and introduce high dynamic carrier synchronization theory, common discriminators such as Costas loop,APAFC,Four-Quadrant frequency discriminator, derived algorithm for these loops and the calculation formula of loop parameters, its tracking performance under different parameters was simulated to determine the different parameters on the performance of loop. A measurement method of SNR and false-lock is proposed to determine the work status of the loop. I use code tracking with carrier aiding, normalized structure of E-L discriminator to reduce the impact of AGC response and high dynamics. Simulate its Simulink model.Finally, use the composite structure of costas loop and the AFC in a highly dynamic environment, achieve its important RTL units in QuatusII, verified it in project board, the actual measurement results show that the algorithm meets the requirements of high dynamic requirement.