【作者】 王新军；

【导师】 曹玉强； 郑明刚；

【作者基本信息】 山东大学 ， 仪器仪表工程， 2008， 硕士

【摘要】 现代生活的方方面面均离不开授时技术,授时方式有多种,其中卫星授时以其全天候、全球覆盖、精度高、可靠性强、使用方便等特点得到了广泛应用。GPS是美国于1993年全面建成的第二代卫星导航系统,它的技术成熟,应用最广泛。该系统实时向用户提供与国际标准时间UTC高度同步的时间,已经被广泛的应用于电力、通讯、航空航天等领域,作为系统的时间基准。文章叙述了基于GPS的时间同步系统的时间同步方法,指出提高同步时间系统的同步脉冲的精确度和稳定度是整个同步系统设计的关键所在。文章通过对GPS时钟的可用性及系统的误差的分析,提出了几种误差校准方法以提高晶体时钟频率测量精度,探讨了系统抗干扰的措施和GPS信号失效后维持同步时钟正常运行的解决方案。B码是时间码IRIG-B的简称,是一种重要的时间同步传输的方式,以其实际优越性能,成为时统设备首选的标准码型。利用B码解码电路,将标准时统设备送来的IRIG-B码,解码出时、分、秒,并加入毫秒信息,送入主计算机,以校准本机的系统时间。本文从硬件和软件设计两个方面,详细介绍该系统的实现。在硬件选择上,由于PIC系列微控制器有抗干扰能力强,性能价格比高等优点,被选为主控制器应用到中央处理单元。GPS时间同步装置主要分GPS信息预处理单元、B码解码单元、同步信号守时电路、同步脉冲信号选择单元、时间信息通信接口和B码编码电路等。其中GPS信息预处理单元提取同步脉冲PPS及时间信息等;B码解码单元用于读取其他时间同步装置传送的B码信息并提取同步脉冲PPS;同步信号守时电路用于装置内部自身产生同步信号,当有外部时间信息输入时,该电路对自身的脉冲进行校正;同步脉冲信号选择单元用于控制同步脉冲的输出方式;时间信息通信接口、B码编码电路用于同步时间信息输出编码。在软件方面,我们介绍了GPS预处理单元、时间同步脉冲守时单元和同步脉冲信号选择单元的软件设计思路。装置经过测试,具有精度高,操作简便,扩展灵活等特点,已批量投放市场。论文最后指出了同步授时装置存在的不足:一是精度有待于进一步提高,二是过分依赖GPS系统,应考虑与其他卫星授时系统(特别是我国的北斗卫星导航系统)的兼容性问题。更多还原

【Abstract】 Time Sevice technology is essential in many aspects in the modern life. There are many kinds of ways about time serve. Among them, satellite time service system has been widely used characterized by all weather, global-mode coverage, high precision, powerful reliability and convenience. Global Positioning System (GPS), the second generation of the Navigation Satellite System, was made in United States in 1993, which were advanced and has been most widedly used.This system real-timely provides the time which is high-synchronic with the universal time to the user. By now, GPS regarded as systemic standard time has been widely used in the fields of the power system, communications, aviation and aerospace.In the present study, we described the synchronous clock method based on the synchronous clock System of GPS and stated that accuracy and stability of the clock pulse of the Synchronous Clock System is the key of the whole synchronous system. By analyzing the availability of the GPS clock and the system error, we proposed that several methods for error standardization in order to increase the frequency measurement accuracy of crystal clock, and explored the jamproof method as well as the solve program of maintaining the normal function of the synchronous clock System after signal becoming invalid.B code is the abbreviate of the time code of IRIG-B. It is an important way for time synchronous transmission and regarded as the first selected standard code of timing equipment because of high performance. By means of B code decoding electric circuit, IRIG-B code transmitted by standard timing equipment is decoded into hour, minute, second, and millisecond information, and imported to the computer for standalization time system of the present machine.The present study described in detail how the system finished from both hardware and software. On the aspect of the hadware, PIC serial micro- controller, which has the powerful jamproof ability, is selected as the main controller and used for central treatment unity. GPS time synchronous system is mainly devided into GPS pre-treatment unit, B code decoding unit, synchronous signal auto-timing circuit, synchronous pulse signal circuit, synchronous pulse signal chosing unit, timing information communication interface, and B code coding circuit. GPS information pre-treatment unit gets out synchronous pulse PPS and timinginformation; B code reads B code information transmitted from other timing synchronous device and gets out synchronous pulse PPS; synchronous signal auto-timing circuit produces synchronous signal by the device itself, which stadars autospecific pulse when the external timing information inputs; synchronous pulse signal chosing unit controls the export way of the synchronous pulse; timing information communication interface and B code coding circuit are responsible for synchronous timing expot. On the aspect of the software, we introduced the ideal of the design of GPS information pre-treatment unit, timing synchronous pulse auto-timing unit and synchronous pulse signal chosing unit.The device was introduced by examples in the present study,including the composition, application, performance index, time sevice ways and the principle, and so on.This system characterized by high accuracy, simple manipulation and active extention, has passed the examination and market launched in batches.There are several limitations in this study. Firstly, accuracy need to be increased. Secondly, overdependence on GPS. Compatibility with other satellite time sevice system needs to be considered, especially with the dipper satellite navigation system in China.更多还原