Research And Implementation Of Free Space Optical (FSO) Communication Transmitter And Receiver

Free-space optical communication is a prospective technology at present. The atmosphere laser communication is it's realizing specifically on earth, and is one of the methods that solve the problem of "The Last One Kilometer" in access network. It is a system easy to be implemented, immediately utilized and is one of the most cost effective broadband wireless solutions that we have seen to date. The atmospheric laser communication technology is primarily feathered by flexible access method and low cost in short distance, compared to fiber transmission capacity, and can be widely applied in the fields of intelligence building and military. This paper makes in detail discussing to the laser transmission subsystem combining one set of 622Mbps multipoint-to-point wireless optical communication equipment.In this paper, we introduce the basic theory, fundamental operating principles and related technology. Based on these theories, explained systematic conceptual design at first, the every part of the system is made simple discussing and analysis in this section. Next, the paper discusses the optical transmission and receiver communication subsystem in detail that includes laser transmission unit; control unit; receiver unit; amplify circuit. And the performance of system is also analyzed. Among this part the key technologies such as automatic power control (APC), LD in laser transmission module; PIN photodiode; transimpedance preamplifier; limiting amplifier are made detailed analysis. Moreover, some important target such as component performance parameter as well as over all system noise; the sensitivity; the dynamic range and so on are analyzed.According to quite mature fiber optical communications, has given the hardware design plan. Corresponding to LD and PIN photodiode, MAXIM Corporation's laser driver chip MAX3738, low power transimpedance preamplifier chip MAX3760, restriction enlargement chip MAX3762 to carry on the system design mutually. To design power circuit, the disposition of peripheral circuit, the transmitting illumination alarm circuit, receiver signal loss indicating circuit. Simultaneously also introduced the PECL level nature and the coupled mode. Has given the concrete hardware schematic circuit, and has carried on the PCB layout.Finally, we set down detailed test plan and make the test. After the test, we draw some useful conclusions and give the guide to the continuous work.