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浏览/检索结果: 共2条，第1-2条 帮助 已选(0)清除 条数/页：5101520253035404550556065707580859095100   排序方式：请选择作者升序作者降序题名升序题名降序发表日期升序发表日期降序提交时间升序提交时间降序 Physical layer design for free space optical communication (EI CONFERENCE) 会议论文 2012 International Conference on Control Engineering and Communication Technology, ICCECT 2012, December 7, 2012 - December 9, 2012, Shenyang, Liaoning, China Wang H.; Guo J.; Wang T.; Zhang Q.; Shao J. 收藏  |  浏览/下载：20/0  |  提交时间：2013/03/25 A small size Free Space Optical Communication System is introduced  including the hardware and the hardware specified physical layer protocol. In detail  the rapid synchronization method to reduce the handshake bandwidth requirement is demonstrated. The hardware of the system includes the laser driver system  the signal amplifying and shaping system  the data interface system. The hardware specified physical layer protocol is used to interface the outer data  serialize and deserialize the data stream  check transmission errors and schedule the data transmission. The overall system is a FIFO-like system and the user can use it as if he's operating a FIFO. The system is designed mainly for terrestrial FSO link whose signal channel is the atmosphere. Due to the complex composition and activity of the atmosphere  this signal channel brings in great influence on the transmitting laser in it  for example  the absorption and scattering of the atmosphere molecules and aerosols  the scintillation of received laser power caused by the turbulence of the atmosphere  all of which results in a much higher Bit Error Rate (BER) of the communication system than wired communication systems leading to frequent resynchronization. In our system  the sampling clock is generated locally using multi-phase sampling technique rather than PLLbased clock recovery  which helps to rapid synchronization. 2012 IEEE.   Transceiving protocol designc for a free space optical communication system (EI CONFERENCE) 会议论文 2008 International Conference on Optical Instruments and Technology: Optical Systems and Optoelectronic Instruments, November 16, 2008 - November 19, 2008, Beijing, China Hualong W.; Wanxin S.; Zhongbao X. 收藏  |  浏览/下载：41/0  |  提交时间：2013/03/25 A new transceiving protocol is demonstrated for a Free Space Optical (FSO) communication system  and it's discussed in two parts: the transmitting protocol and the receiving protocol. During the discussion of these two parts  the cooperation of them is also discussed. Different from wired communication  an FSO system modulates the data on a narrow beam of laser transmitting through the free space or the atmosphere  and the protocol presented in this paper is mainly optimized for terrestrial Free Space Optical links  in which the signal channel of the system is mainly the atmosphere. Due to the complex composition and activity of the atmosphere  this signal channel brings in great influence on the transmitting laser in it  for example  the absorption and scattering of the atmosphere molecules and aerosols  the scintillation of received laser power caused by the turbulence of the atmosphere  all of which results in a much higher Bit Error Rate (BER) of the communication system. Thus in designing a protocol for an FSO system  more effort should be taken in the encoding of the data stream  the synchronization of the data stream  error checking and exception handling. The main function of the transmitting protocol includes interfacing the outer input data with a parallel port  buffering the input data  encoding the input data stream  serializing the parallel data and output the serialized data. It also has an output management unit to manage the activity of each part of the transmitting protocol. The main function of the receiving protocol includes filtering and synchronizing the input serial data stream  paralleling the serial data stream  decoding the input data  error checking  exception handling and interfacing the outer receiver with a parallel port. The entire transceiving protocol could be programmed into a single FPGA chip to improve system integrity and reduce the system cost. The presented protocol could be taken as "protocol transparent" for outer interfaces  meaning that when interfacing the presented system to an outer system  you don't have to consider what protocol the outer system transceiving data stream is under  for example  the TCP/IP protocol or anything else  in the case that its I/O interface is a parallel port. Simulation and final experiment prove that the protocol presented is working fine at a certain bit rate scale. 2009 SPIE.