GHz伪随机码脉冲序列发生电路设计与实现

摘要时间相关单光子计数技术(TCSPC)应用于激光测距领域可以实现高距离分辨精度的测量。但是，在长距离测量中，TCSPC激光测距系统有一个主要弱点——距离模糊。距离模糊是指长距离测量中，由于TCSPC系统无法确定接收脉冲与发送脉冲的对应关系，而导致无法确定目标确切距离的现象。为避免距离模糊问题，一个可行的方法是将周期性脉冲序列替换为随机产生的非周期性脉冲序列。
本文研究的课题作为TCSPC激光测距系统的一部分，主要内容是设计一个伪随机码生成与脉冲序列输出系统，用来驱动可编程激光器。在查阅大量文献的基础上，本设计选用LabVIEW FPGA作为为开发平台，采用一文布尔数组作为序列生成与传递的载体，串行输出脉冲序列。由于所得串行输出数据率不能满足TCSPC系统要求，本设计提出了采用一文U16数组作为载体，16通道并行输出的改进方案。最终，由于硬件性能以及PCB电路原因，得到串行输出数据率25MHz，并行输出12MHz，不能完全满足TCSPC系统实际使用的要求，还有待今后进一步地研究和改善。
关键词伪随机码序列 LabVIEW FPGA PCB设计6486
毕业设计说明书（论文）外文摘要
Title     Circuit Design and Implementationg of the GHz pseudo-random code pulse sequence
Abstract
Time-correlated single photon counting technique (TCSPC) used in the field of laser ranging can achieve high time –resolved measurement of the accuracy. However, in the long-distance measurements, TCSPC laser ranging system has a weakness – the rang ambiguity. Range ambiguity is the phenomenon that TCSPC system cannot determine the correspondence between receiving and sending pulses so that it cannot establish the exact distance in long-distance measurement. In order to avoid the range ambiguity, a viable solution is using a randomly generated a periodic pulse sequence instead of the periodic pulse.
The subject of this study as part of the TCSPC laser ranging system, the main content is to design a pseudo-random code generated pulse train output system which is used to drive the programmable laser. After accessing to extensive literature, the design uses the LabVIEW FPGA as the development platform. It uses a   one-dimensional Boolean array as the carrier of the sequence generation and transmission to output the pulse sequence serially. Because the serial output data rate cannot meet the TCSPC system requirements, the design proposed a improvement program which uses a one-dimensional U16 array instead of the one-dimensional Boolean array as the carrier. Because of the reason of hardware performance and the PCB circuit, the data rate of serial output is 25MHz and the data rate of parallel output is 12MHz, which cannot fully meet the actual requirements of the TCSPC system. It remains to be further research and improve.
Keywords pseudo-random code pulse sequence   LabVIEW FPGA PCB design
目   次
1 绪论 1
   1.1课题背景及意义 1
   1.2本文的研究内容 2
2伪随机码序列 3
   2.1伪随机序列的概念 3
   2.2 伪随机序列发展历史与研究现状 3
   2.3 伪随机序列的应用 3
3 设计工具介绍4
3.1 LabVIEW开发平台4
   3.2 PCB设计 8
4 伪随机码序列生成与脉冲序列输出 11
   4.1伪随机码序列生成 11
   4.2脉冲序列输出 12
5 设计方案改进 19
   5.1改进方案 19
   5.2设计修改 19
   5.3结果分析与改进方法 23
结论 24
致谢 25
参考文献 26
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