"北斗"陆基增强系统导航信号源的分析与设计

导航信号激励器是无线电导航系统的关键设备。简要介绍了通过建立陆基增强系统来提高"北斗"定位能力的技术方案,并对陆基增强系统扩频导航信号激励器进行了详细的分析与设计。利用直接频率合成(DDS)技术产生高精度、高稳定度的码时钟,并利用AD9854芯片特有功能实现BPSK调制;采用CPLD器件设计扩频伪码产生器及扩频调制器。文中还着重讨论了各陆基导航台时钟同步的几项关键技术。实测结果表明:所设计实现的导航信号激励器精度高、稳定性好;并且BPSK调制实现了较好的载波抑制,隐蔽性好、抗干扰能力强。

Analysis and Design of the Navigation Signal Generator of "Beidou" Terrestrial Improvement System

The navigation signal generator is an essential device in radio navigation and position system. The technique scheme of improving the "Beidou" positioning ability through setting up terrestrial improvement system is briefly presented, and the system signal generator is analyzed in detail and designed. In the design, the Direct Digital Synthesis (DDS) is adopted to create pesudo random code clock with high precision and high stability, the special function of DDS chip AD9854 is used to realize BPSK modulation, the CPLD device is applied to design spread spectrum pseudo random code generator and spread spectrum modulator. Some key techniques of the time synchronization for each terrestrial navigatioin station is specially discussed. The results of practical measurement indicate that the signal generator has high precision and nice stability; moreover the BPSK modulation makes carrier suppression with good concealment and strong anti-jamming ability.