可重构激光雷达数据采集平台研究

发布时间：2018-08-15 19:27

【摘要】：激光雷达以具有极佳方向性、单色性及相干性的高强度激光为探测信号,不仅能够获得更高的探测精度和范围,更重要的是能够探测无线电雷达无法探测到的微小粒子,以及各种分子、原子,并对探测目标进行识别和分类。这些特性使激光雷达在大气环境监测、海洋科学以及生物医学领域获得了广泛的应用,因而激光雷达是一个庞大的类型繁多的综合体系,这也影响了数据采集系统的多样性和复杂性。当前激光雷达数据采集系统并非由单一器件能够完成,而是多种设备或采集卡的组合,例如高端数字示波器,多通道扫描仪(MCS), NI集成化设备,以及Licel公司的TR产品等,这些数据采集产品的引入大大提高了采集精度,使用也更为简便。但是鉴于激光雷达的新技术不断出现、需求不断提升,也使许多研究单位为各自的项目专门设计匹配性强的数据采集卡。一方面激光雷达的快速发展和市场化,要求模块化、标准化、集成化的产品使研发成本降低；另一方面,为了保证科学研究的先进性,获得市场竞争优势,期望出现开放式而非定制的数据采集系统允许使用者再开发。这已成为了亟待解决的问题,因此本论文提出建立可重构激光雷达数据采集平台(RLDAP)。RLDAP不仅进一步扩大在激光雷达中的使用范围,而且增强了可移植性和兼容性,为系统升级更新预留资源,最大限度的服务于未来新型激光雷达的研制工作,减少重复的资金投入和人力投入,从而发挥出更大的经济效益和社会效益。为此,本论文在归纳了激光雷达发展历史和现状的基础之上,深入调研了激光雷达整机尤其是光学接收、光电探测部分的原理,总结了激光雷达数据采集系统的规律性和特异性,从而开展了可重构激光雷达数据采集平台的设计工作,并通过实验室测量和现场对比实验证明了其实用性。本论文的创新点主要有： (1)首次将可重构仪器的概念引入激光雷达探测领域,并对源于计算机领域的可重构概念实现扩展和延伸。可重构的意义不再局限于软件或是硬件,而是多部件重构、软硬件重构的融合,包括硬件资源的重组,FPGA的逻辑在线重配置,多处理方式并存的通信协议,软件的组合、动态调用等。 (2)在国内率先自主研发分层探测模式的数据采集系统,使信号的线性探测动态范围达到5-6个数量级,达到国际先进水平。尽管国内已有应用于极弱光探测的单光子计数仪器和用于强光探测的AD转换采集卡,但均不具备大动态范围、高信噪比的探测能力。而RLDAP的研制克服了双模式数据拼合区数据探测的难点,打破了长期依赖国外单一产品的限制。 (3) RLDAP在现场实验中被证明可以覆盖近地面和中高空领域的探测,且适用于传统方式和新型微脉冲等多类型的激光雷达。RLDAP已被成功用于Rayleigh多普勒测风激光雷达和大气能见度仪的探测中,特别是对于20-60km临近空间风场的探测实验,RLDAP同步实现了光子计数的高速高增益放大和A/D转换带宽内模拟信号的严格线性放大,提高了模拟探测对弱信号的分辨能力,成功解决了低层强信号非线性堆积和高层微弱信号的低信噪比问题,这是探测技术中的难点。该项实验是在国内首次实现对平流层至中间层底部的风场测量。
[Abstract]:Lidar uses high-intensity laser with excellent directivity, monochromaticity and coherence as detection signal, which can not only obtain higher detection accuracy and range, but also detect tiny particles, as well as various molecules and atoms that can not be detected by radio radar, and identify and classify detection targets. Lidar has been widely used in atmospheric environment monitoring, marine science and biomedical fields. Therefore, lidar is a huge and various integrated system, which also affects the diversity and complexity of data acquisition system.
At present, the data acquisition system of lidar is not completed by a single device, but a combination of various devices or acquisition cards, such as high-end digital oscilloscope, multi-channel scanner (MCS), NI integrated equipment, and Licel TR products, etc. The introduction of these data acquisition products greatly improves the acquisition accuracy and is more convenient to use. In view of the continuous emergence of new technologies and increasing demand for lidar, many research institutes specially design matching data acquisition cards for their own projects. It has become an urgent problem to solve. Therefore, this paper proposes to establish a reconfigurable lidar data acquisition platform (RLDAP). RLDAP not only further expands the scope of application in lidar, but also extends the scope of application in lidar. It also enhances the portability and compatibility, reserves resources for system upgrade and upgrade, maximizes the service for the future research and development of new lidar, reduces the duplicate capital investment and manpower investment, thus playing a greater economic and social benefits.
Therefore, on the basis of summarizing the development history and current situation of lidar, this paper investigates the principle of the whole lidar, especially the optical receiving and photoelectric detecting part, summarizes the regularity and specificity of the lidar data acquisition system, and develops the design work of the reconfigurable lidar data acquisition platform. The practicality is proved by laboratory measurement and field contrast experiments.
The innovations of this paper are as follows:
(1) Introducing the concept of reconfigurable instruments into the field of lidar detection for the first time, and expanding and extending the concept of reconfigurable instruments from the field of computer. The meaning of reconfiguration is no longer confined to software or hardware, but is a combination of multi-component reconfiguration, software and hardware reconfiguration, including hardware resource reconfiguration, logic on-line reconfiguration of FPGA, and multi-processing. Communication protocols, software combinations, dynamic invocation and so on.
(2) The data acquisition system of layered detection mode has been developed independently in China, and the linear detection dynamic range of the signal has reached 5-6 orders of magnitude, reaching the international advanced level. The development of RLDAP overcomes the difficulty of data detection in dual-mode data fusion area and breaks the restriction of long-term dependence on foreign single product.
(3) RLDAP has been proved to be able to cover near-ground and high-altitude detection in field experiments, and can be used in many types of lidars, such as traditional and new micro-pulse lidars. RLDAP has been successfully used in Rayleigh Doppler wind lidar and atmospheric visibility instruments, especially in the detection of wind fields in the near space of 20-60 km. Experiments show that RLDAP synchronously achieves high-speed and high-gain photon counting amplification and strict linear amplification of analog signals in A/D conversion bandwidth, improves the resolution of weak signals in analog detection, and successfully solves the problems of nonlinear accumulation of low-level strong signals and low signal-to-noise ratio of high-level weak signals, which are the difficulties in detection technology. It is the first time to measure the wind field in the stratosphere to the bottom of the middle layer in China.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN958.98

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