【作者】 孟劲松；

【导师】 林建辉；

【作者基本信息】 西南交通大学 ， 载运工具运用工程， 2008， 博士

【摘要】 随着现代科学技术的进步,对测试理论、测试仪器和测试系统提出了更高的要求。目前,桥梁、轨道、爆破、地震勘探等野外中远程分布式测试应用越来越多,无线集散型分布式测试系统(WSG-DTS,WirelessScatter/Gather Distributed Testing System)是最适合这种应用的,然而目前用于WSG-DTS的仪器存在数据传输率低、定时与同步精度差等问题,因而对适合野外中远程分布式测试应用的无线扩展仪器的关键技术进行研究,对于国民经济建设有着重要意义。主要研究内容和成果如下:1.对目前各种现代通用测试仪器和测试系统进行较为全面的总结与分类,分析其发展的内在动因和发展趋势,给出仪器发展树,为新型总线仪器奠定正确的研究方向。2.根据仪器的发展规律和现代仪器的关键技术研究,针对当前野外DTS存在的数据传输率低、定时与同步精度较差等问题,提出适合无线集散型分布式测试系统(WSG-DTS)应用的无线扩展仪器(WXI,WirelesseXtensions for Instrumentation),对无线总线、定时与同步等关键技术的深入研究是解决上述问题的的关键。3.针对中频数字化无线通信系统(中频带通采样软件无线电),从理论上指出抽样误差实质上是载波累积误差的一个因素,从而使得载波同步同步算法大为简化。针对莱斯信道,给出突发OFDM系统一种基于恒包络连续相位导频符号的载波捕获和定时的联合算法,研究表明基于这种导频符号的定时偏差成随机分布,最大偏差为亚纳秒。研究了无线通信技术的仪用扩展性,选择固定突发OFDM无线链路为无线总线,研究表明无线总线的数据传输率远远超过目前一些SG-DTS和无线传感器网络(WSN,Wireless Sensor Network)的数据传输率,可以满足大多数DTS的应用。4.建立基于固定突发OFDM无线总线的WSG-DTS和模块化WXI的系统结构模型。基于SOPC和软件无线电,给出了WXI总线桥的实现方法。针对多通道测试,提出一种基于模块化高速SCSI磁盘实时记录仪的海量数据存储策略,并给出了这种海量实时数字化记录仪的实现方法。5.分析研究了固定突发OFDM无线总线的传输延迟因素,研究表明延迟的抖动范围为亚纳秒。对LXI同步协议进行了改进,给出了一种WXI定时与同步协议(WTSP)。在这个基础上,进一步研究了WXI的定时与同步,给出了基于最大传输延迟、最小传输延迟的两种触发同步方法,以及基于GPS秒脉冲和DDS、本地时钟与WTSP联合的两种采样时钟同步算法。针对野外分布式测试应用,给出了基于WXI的WSG-DTS的系统结构,以及嵌入式WTSP引擎的运行机制。更多还原

【Abstract】 The science and technology is rapidly developing every day, which pushes the test theory, instrumentation and Auto Test System(ATS) to progress. Today, the field remote Distributed Test System(DTS) has been widely applied in tests of bridge, railway, blasting, seismic exploration, and the like, among which the Wireless Scatter/Gather Distributed Testing System(WSG-DTS) is the best ATS for the above-mentioned. However, some weakness, such as low speed of data trasmission and low precision of T&S are associated with current WSG-DTS, so the study of key technology of Wireless extensions for Instrument which can be preferably appled in the field remote Distributed Test System is significant for the development of national economy. The following is the main content and production of the study:1. The instrument development tree is presented basing on the sum-up of all modern kinds of general instruments and test systems, which give directions for the study of new generation instrument.2. For the problems ocurr in the existing field remote DTS, such as low speed of data trasmission and the low precision of T&S, this paper advances an idea of Wireless extensions for Instrument(WXI) based on the development law of modern instumentation and the study of the modern instrument key technologies, Wireless Bus and T&S are the key stones.3. The research of IF digitalization communication sysytem theoretically indicates that the sample error is essentially a factor of the accumulative carrier error, which simplifies the algorithm of carrier synchronization. A joint algorithm of Pilot-symbol-aided frequency and timing synchronization with constant envelope and continuous phase modulation over the Ricean channel, is offered here, which tell us that the pilot-symbol timing offset is stochastic, and limited to Sub-nanosecond. The study of wireless extensions capability for instrument based on fixed OFDM in burst mode showes that the bandwidth of OFDM is greater than the current SG-DTS and Wireless Sensor Network(WSN), and the Wireless Bus can satisfy most DTS application requirements.4. This paper comes up with a WSG-DTS with modular WXI model and a WXI bus-bridge established on System On programmable Chip(SOPC) and Soft Defined Radio(SDR). To realize the multi-channel test, a strategy and design method of high speed SCSI drive real-time mass data storage is provided here. 5. The research of Wireless Bus transmmition delay finds that the dithering of the delay is scaled within sub-nanosecond. Standing on that, this paper logically illuminates the WXI T&S Protocol(WTSP) based on the modification of LXI synchronization Protocol. Then the methods for trigerring synchronization with maximum transmission delay or minmum transmission delay and sample clocks synchronizing are introduced. The algorithm of sample clocks synchronization can be deduced from GPS PPS(Pulses Per Second) and DDS(Direct Digital synthesis), or Local Oscillator(LO) and WTSP jointly. Lastly the WSG-DTS system structure with WXI is discussed, and one embedded WTSP engine is presented in the end.更多还原