Design And Performance Evaluation Of Spread Spectrum Code For Satellite Navigation Signal

The project comes from the research on anti-jamming of satellite navigation system,a prospective pre research project in the field of satellite navigation participated by the national time service center.Scientists put forward the design idea of system changing satellite,code and frequency,so as to improve the anti-jamming and anti destruction ability of satellite navigation system.The transcoding scheme requires the design of 40-60 groups of codes.Each code cluster contains multiple groups of code sequences.When the system is disturbed,the spread spectrum code switches from one code cluster to another,which requires a high number of spread spectrum codes with excellent performance.At the same time,with the rapid development of satellite navigation technology,countries are competing to develop their own satellite navigation systems,and the number of space satellites is increasing rapidly,which puts forward more stringent requirements on the number of spread spectrum code clusters used to distinguish different satellites and affect the ranging accuracy and the performance of ranging cross-correlation.In this paper,based on the optimization of the spread-spectrum codes with a large number of code clusters and excellent comprehensive performance,the design,optimization and performance evaluation of the spread-spectrum codes of satellite navigation signals are studied1. The results show that Kasami code is a kind of spread spectrum code generation method with low complexity and excellent cross-correlation performance,which is suitable for popularization and application.However,the number of code families generated by Kasami code generation method currently used is small,which can not meet the application requirements of"anti-interference research of satellite navigation system".A new spread spectrum code based on Kasami code is designed.The design flow of the new spread spectrum code is given and compared with the traditional Kasami code.The results show that the correlation performance of the new spread spectrum code is equivalent to that of the traditional Kasami code,and the the spread spectrum code).2. The undirected graph model is introduced into a traditional spreading code optimization method,which reduces the computation complexity of cross-correlation optimization from O(~2)to O(M).The simulation results show that the performance of the improved method is better than the other three methods.3. Based on the important influence of spread spectrum code balance on the receiving and transmitting performance of navigation signal,balance e is added to the traditional comprehensive evaluation function based on Welch bound,forming a more comprehensive and new comprehensive evaluation function.4. The optimized spreading code can meet the application requirements of"anti-jamming research of satellite navigation system"for the high cross-correlation performance of spreading code and the large number of code clusters;the generation,optimization and evaluation methods of spreading code can provide reference methods and basis for the optimization of high-performance spreading code in the expansion and enhancement of existing satellite navigation system,and provide reference for the design of spreading code in new navigation system It provides a complete set of method support for generation,optimization and performance evaluation,and provides theoretical method and design reference for the designers of navigation system spread spectrum code.