摘要
美国全球定位系统(Global Positioning System,GPS)现代化建设使得L1频点同时支持播发L1 C/A和L1C信号,具有同频双信号的特点,为GPS信号捕获技术研究提供了更多可能。针对GPS L1C信号测距码长、捕获运算量大、耗时久的问题,利用L1 C/A与L1C信号之间码相位延时和Doppler频率的关系,提出并实现了一种基于GPS L1 C/A辅助的L1C快速捕获算法。该算法首先对L1 C/A信号进行捕获跟踪,获得码相位和Doppler频率;再通过L1 C/A信号Doppler频率剥离L1C信号载波,同时利用L1 C/A码相位产生多个相位偏移修正的L1C码序列;最后通过不同相位偏移的L1C码序列最大相关积分值的判定,获取L1C捕获结果。通过实测数据对算法性能进行测试,结果表明:相较未使用辅助信息的捕获算法,该算法可以有效提高接收机对L1C信号的捕获速度,对单颗L1C卫星信号捕获耗时下降约85.56%,具有一定的工程意义。
The global positioning system(GPS)has the characteristics of GPS L1 dual signal on the same frequency.The GPS modernization program is the addition of new navigation L1C signals to the L1 C/A satellite constellation.The sys⁃tem provides more possibilities for GPS satellite baseband signal processing technology research.Aiming at the problems of long L1C signal ranging code,long acquisition time,and a large amount of operation,based on analysis of the acquisition process information between L1C and L1 C/A signal,such as code phase delay and Doppler frequency,a GPS L1 C/A sig⁃nal⁃assisted fast acquisition algorithm for L1C signal is proposed and realized.Firstly,the code phase and Doppler frequen⁃cy are obtained through the L1 C/A signal acquisition and tracking process.Then,the L1C signal carrier is stripped away by the Doppler frequency,and multiple offset⁃corrected L1C code sequences are generated using L1 C/A code phases.Fi⁃nally,the L1C signal acquisition information is obtained by determining the maximum integral value of L1C code sequences with different phase offsets.At the same time,the test based on the real signal verifies the correctness and reliability of the algorithm.The results show that this algorithm can increase the speed of single L1C signal acquisition,and the acquisition time is significantly reduced by about 85.56%,compared to the acquisition algorithm that does not use assisted informa⁃tion,so it has certain engineering significance.
作者
罗凯
许睿
陈佳林
曾庆化
LUO Kai;XU Rui;CHEN Jia⁃lin;ZENG Qing⁃hua(Navigation Research Center,College of Automation Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 211106)
出处
《导航与控制》
2023年第1期54-60,共7页
Navigation and Control
