Design And Implementation Of An Ultraviolet Communication Hardware Platform

Ultraviolet(UV) communication is a kind of free space optical communication. Compared with other communication meanings, it has advantages of high confidentiality, strong anti-interference capability, good maneuverability, supporting all-weather work and non-line-of-sight (NLOS) communication because its carrier beam is in solar-blind region(200nm to280nm). In recent years, UV communication has attracted more and more attention and becomes a hot spot research in communication field. Research institutions over the world put a great deal of research effort in studying the key UV components, analyzing channel models, implementing UV systems and designing protocols. At present, the domestic and foreign experimental platforms don’t do well for their signal processing in physical layer and doesn’t take into account the scalability to upper layer.The first chapter describes the characteristics of UV communication, presents the current developments of UV communication at home and abroad, and introduces the research purpose and contents of this thesis.The second chapter reviews the principles of UV communication, including atmospheric transmission characteristics and single scattering channel model. Then, several kinds of UV light sources and detectors are analyzed and compared in terms of conversion efficiency, response speed, cost, etc. Based on the analysis, the UV LED and photomultiplier tube (PMT) are used in our hardware platform.The third chapter elaborates the design of UV communication modules. First, the features and processes of FPGA development are introduced. Then, the structure of physical layer modules are described, including asynchronous FIFO(First In First Out queue), phase lock loop, A/D(Analog/Digital conversion), judgment, scrambling, and modem. The control mechanism and signal flow between these modules are also explained. Furthermore, we investigate some widely-used data link layer protocols, including BSC(Binary Synchronize Control), PPP(Point to Point Protocol), HDLC(High-Level Data Link Control) and MAC(Medium Access Control) protocols, and choose HDLC as the data frame encapsulation protocol in our platform.Chapter4gives the design of extended circuit board. It provides power supply and control of UV LED and PMT, and transmits and receives data through the interface with FPGA.Chapter5presents the simulation and experimental results of some key modules and the overall system. These results verify the design of our UV communication system, and show that our system can support indoor communication at the data rate of38.4kbps.The last chapter summarizes the work that I have done, points out some remaining issues and work for future study.