The Design And Realization Of Optical Fiber Transmission System Suitable For Low Temperature Work

With the development of communication technology , it is a crucial problem that how to transmit data correctly under so complicate electromagnetic environment . Compared with cable transmission , fiber transmission has the strongpoint of electromagnetic interference proof and is light . So it is adopted widly as transmission channel , moreover , temperature-resist of system is also required strictly . Spur track signals require to be multiplexed to transfer through a single optical fiber . And multiplexed signals need to be 8B/10B encoded to adapt the fiber . Positive justification is important to the system , so realizing with FPGA is worth researching . BER tester is often used to check the system's performance , but it's expensive , so I design a simple BER tester with a FPGA . The system introduced in this paper has the function of multiplexing and de-multiplexing of 8channels parallel differential digital signals , encoding and decoding of optical fiber line code 8B/10B , positive justification with a FPGA , BER tester with a FPGA and fiber transmission of high bit rate digital signal ,and running correctly in low-temperature enviroment. The following work has been done: 1. Analyzing what happened when fiber module working in low temper , and have it made to meet the low temper . 2. According to the system required , scheming the system , designing hardware circuits , which work correctly in low temperature , including teansmitting circuit and receiving circuit , debugging them . 3. Testing the BER of system in normal temperature , doing an experiment in low temperature enviroment and testing the BER of it . 4. Realizing positive justification and simple BER tester with a FPGA individually . The system run correctly at –45℃, has excellent BER performance , its BER is 10^-11 when transmitting with 8 channels in low temperature, which achieve the system's requiring .