基于QD的跟踪与通信复合探测技术研究

发布时间：2018-12-23 08:25

【摘要】：空间光通信凭借其通信频带宽、传输速率高、抗干扰抗截获能力强的优势,成为解决射频空间通信中带宽接近极限、通信速率难以提高问题的有效方式之一,正成为星间、星地等通信链路的主要发展趋势。针对地面近距离低速率的大气激光通信的应用需求,本文研究的基于QD(四象限探测器)的跟踪与通信复合探测技术对光通信终端的低功耗、轻小型化设计至关重要。经典空间激光通信光端机采用精跟踪与通信分离,独立发射独立接收探测,对跟踪视轴和通信视轴的同轴度要求很高。而跟踪与通信复合探测技术,仅利用一个四象限探测器来接收信号光同时完成精跟踪和通信功能,简化光端机结构,降低系统功耗。本文首先介绍了QD在空间激光通信中的应用现状,其次分析了复合探测的前提条件和主要特点,然后对四象限探测器的光斑位置检测原理进行了阐述,分析了光斑尺寸、光斑位置、背景光、光斑能量分布、死区宽度、信噪比对光斑位置检测精度的影响;提出了基于四象限探测器的跟踪与通信复合探测技术的具体方案,设计并实现了复合探测系统的硬件电路功能,包括激光调制发射单元、光电转换探测和前端信号处理单元、跟踪伺服单元和通信解调单元。最后搭建了实验系统,采用800nm通信光在曼彻斯特编码、强度调制/直接探测条件下,通信速率达到10Mb/s,探测灵敏度-35.4dBm,误码率10-6。光斑位置检测的最小位置分辨率是2μm,角分辨率是0.8μrad,闭环跟踪系统的跟踪精度是2.5μrad(峰峰值)。本文初步论证了利用QD单探测器实现跟踪与通信复合探测的可行性,为整个通信系统的应用设计打下基础。
[Abstract]:Because of its advantages of high frequency bandwidth, high transmission rate and strong anti-jamming and anti-interception ability, space optical communication has become one of the effective ways to solve the problem that the bandwidth is close to the limit and the communication rate is difficult to improve in radio frequency space communication. The main development trend of satellite-ground communication links. In order to meet the requirement of the application of low speed and close distance atmospheric laser communication, the tracking and communication compound detection technology based on QD (four-quadrant detector) is very important for the design of low power consumption and light miniaturization of optical communication terminal in this paper. The classical space laser communication optical terminal adopts the separation of fine tracking and communication and independent transmitting and independent receiving detection. The coaxiality of tracking axis and communication axis is very high. In the complex detection technology of tracking and communication, only a four-quadrant detector is used to receive the signal light and complete the functions of fine tracking and communication simultaneously, which simplifies the structure of the optical terminal and reduces the power consumption of the system. This paper first introduces the application status of QD in space laser communication, then analyzes the premise and main characteristics of compound detection, then expounds the principle of spot position detection of four-quadrant detector, and analyzes the spot size. The influence of spot location, background light, spot energy distribution, dead zone width and signal-to-noise ratio on spot location detection accuracy; In this paper, the specific scheme of tracking and communication compound detection technology based on four-quadrant detector is presented, and the hardware circuit functions of the compound detection system are designed and realized, including laser modulation emitter unit, photoelectric conversion detection unit and front-end signal processing unit. Tracking servo unit and communication demodulation unit. Finally, an experimental system is set up. Under the condition of Manchester coding, intensity modulation / direct detection, the communication rate is 10MB / s, the detection sensitivity is -35.4dBmand the bit error rate is 10-6. The minimum position resolution of spot detection is 2 渭 m and the angular resolution is 0. 8 渭 rad,. The tracking accuracy of the closed loop tracking system is 2. 5 渭 rad (peak). This paper preliminarily demonstrates the feasibility of using QD single detector to realize tracking and communication compound detection, which lays a foundation for the application design of the whole communication system.
【学位授予单位】：长春理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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