【作者】 雷小明；

【导师】 肖沙里；

【作者基本信息】 重庆大学 ， 光学工程， 2008， 硕士

【摘要】 紫外光通信是一种新型的自由空间光通信方式,它具有一些特殊的优点,如保密性好、抗干扰性能强,非直视通信等。因此,紫外光通信非常适合应用在一些对保密性要求高,地形复杂的场合。太阳紫外辐射在通过大气层时,不仅由于氧气作用滤去了其中的真空紫外成分,而且由于在对流层上部的臭氧层对300- 200nm紫外线有强烈的吸收作用,太阳的这一波段紫外辐射在近地大气中几乎不存在,形成所谓日盲区。该区域的紫外光用于通信,具有背景干净,抗干扰性强的特点。因此本系统选定了波长为254nm的紫外光作为自由空间光通信的载体。同时由于紫外光独特的强散射性,决定了其能实现特定区域范围内非视距通信,这是日盲紫外光通信相对于其他通信方式的又一优点。文章首先对紫外光的传输特性进行了分析,说明了大气层,空气中的介质,以及大气湍流对紫外光传输的影响。引入Luegtten等人提出的基于椭球坐标系的单散射信道模型,对紫外光在NLOS方式下的传输能量接收做出了定量的分析。根据Zhengyuan Xu在该模型下的实验结论,对紫外光通信中的发送和接受角度选择做出了优化性建议。其次,根据紫外光的特性,详细讨论了搭建紫外光通信系统关键器件的选择。低压汞灯因其高转换效率,功率范围宽,光谱线集中在日盲段(辐射出约90%的253.7nm紫外光)等优越性能成为本系统的发射光源。并以此展开介绍了以光电倍增管为核心的接收装置;简单说明了AD73311L,AMBE2000,以及51单片机组成的语音处理系统。详细介绍了低压汞灯的发光特性及过程,综合考虑基带信号的为二进制式,系统最终选用2FSK调制方式。第三,由于低压荧光灯使用电子镇流器作为驱动电路,分别设计了半桥谐振电路、L6574主控芯片、以L6574为核心的APFC电路、浪涌电流抑制电路和EMI滤波器的工作原理和设计过程。本设计的目的是结合现阶段技术条件,对于紫外光语音通信进行了初步探索。经过多次实验表明,本系统已经实现了距离10~60m范围内,速率为9.6Kbps下低误码率的文字信息紫外光通信。为进一步实现实时语音通信打下了坚实的基础。文章最后给出了实验结果和展望。更多还原

【Abstract】 Ultraviolet Speech Communication is a new type communication system in free space optics communication field. Some excellent performances such as safety,anti-interference, Non Line-of-Sight, make it different from other communication mode. Hence, ultraviolet optics communication may be applied in some special occasion to make up for the shortage of traditional communication modes.When the solar ultraviolet radiation pass through atmosphere, oxygen will filter out the vacuum ultraviolet, and furthermore, the ozonosphere over the troposphere absorbs the 200-300nm ultraviolet band so strongly that it can not reach ground surface. The ultraviolet is so-called solar-blind ultraviolet. In practice, the 254nm ultraviolet was selected as free space optics communication carrier. And ultraviolet is suitable for Non Line- of -Sight communication for its high level scattering performance. It is also another advantage compared with other models.Firstly, this paper analyses the factors, such as atmosphere, atmosphere media and atmospheric turbulent, that effect Ultraviolet Optics transmitting performance. Introduce the single - scattering model based the ellipse - spherical coordinate system. Employing it, the receiving optic power transmitted in NLOS style can be calculated. And according to the experimental conclusion of Zhengyuan Xu, the transmiting and receiving angle can be optimized.Secondly, according to the ultraviolet characteristics, some important devices are discussed and selected. For some superiorities such as high transforming efficiency, wide power range, excellent spectral line performance, the low voltage mercury lamp was used. And then, we discussed the ultraviolet receiver based PTM, and introduced speech process system which consist of AD73311L, AMBE2000 and 51 microcontroller.To make the right modulation scheme, the low voltage mercury lamp lighting characteristics is specified. And also considering the baseband signal is a binary style, the 2FSK model finally was selected.Thirdly, mercury lamp is driven by electronic ballast, so half-bridge resonance circuit,L6574 control chip circuit, APFC circuit based on L6561 and EMI filter are introduced both in working principle and design process. The purpose of the design is to utilize the current technology and resource to do some elementary research on ultraviolet optics speech communication. For three years hard works, we accumulated some experiences in modulating of ultraviolet optics and speech encoding. In present, the system can transmit character information in 9.6Kbps with a low bit error rate. It testifies that real-time ultraviolet speech communication can be realized.更多还原