【作者】 闵紫辰；

【导师】 高西全；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2005， 硕士

【摘要】 随着现代通信对时间同步性能的要求不断提高，时间传递的方式变得越来越重要。现行的高精度远距离时间传递方式主要有GPS共视法和双向卫星时间传递技术(TWSTT)。虽然GPS共视法被广泛应用，但它由美国国防部控制，其应用范围受到限制。TWSTT一直作为GPS时间比对的一种辅助手段，由于其高精度的时间传递性能，一直是这个领域的研究热点。本文主要研究双向卫星时间传递中频调制解调器的实现。首先详细介绍了双向卫星时间传递的基本原理和多站数据处理的方法，然后在TWT-100设备的基础上，分析了信号流程和系统的各个组成部分：接着对系统中所涉及的带通采样、扩频解扩、载波恢复和锁相环技术进行了说明；随后给出了双向卫星时间传递系统数字中频发射和接收部分的设计方案，对所采用技术的原理进行了详细的分析。伪码捕获采用时域／频域二维N通道捕获的方案，载波恢复采用FLL和PLL相结合的方法，相位角的计算采用旋转坐标数字计算机的方法；最后给出了扩频模块、载波数控振荡器模块、伪码捕获模块和CORDIC模块的硬件实现。更多还原

【Abstract】 Time transfer methods are becoming increasingly important in the world of high-speed communication, global navigation and precision metrology. There are two primary methods of time dissemination around the world: two-way satellite time transfer_TWSTT and common-view Global Position System_GPS time transfer. There is a catch: GPS is a United States Department of Defense system, its applications are limited. TWSTT is often used as a secondary measurement to GPS or a sole means time recovery with performance that is superior to GPS time transfer, so it has been a hot topic in time community all the time.In this thesis, digital IF time transfer modem is mainly studied. In the second chapter, the principle of two-way time transfer with emphasis on its use with commercial communications satellites is firstly introduced in detail, then a new method of processing multi-stations data is presented; finally the signal flows and components are analyzed based on TWT-100. In the third chapter, some key technologies concerned with digital IF modem are introduced, such as PN sequence acquisition and tracking, carrier recovery and phase locked loop. In the fourth chapter, the IF modem implementation structure of two-way time transfer is presented. Frequency/time two dimension N channels acquisition is adopted in PN sequence acquisition, frequency locked loop and phase locked loop are used in carrier recovery, coordinated rotation digital computer is employed in phase computing. In the fifth chapter, hardware implementation of spread spectrum modulation module, sequence acquisition module, carrier NCO module and CORDIC module are given.更多还原