The Design And Implementation Of Data Transmission System Base On Unidirectional Fiber Optic Transmission Equipment

In the information and digital times,the use of Internet is widespread.The Internet has become part of our daily life and production activities.While we are enjoying the convenience of the Internet,the security of the Internet is challenged.Computer users are under constant threat from computer viruses,Trojan horses and malicious software.Accordingly,the network security is becoming increasingly important for people.The transfer of information cannot be in progress without the Internet in the production activities of an enterprise.In order to prevent huge risk and unpredictable loss of the information leakage,the network security in transferring information becomes particularly important,such as exchanging files and database information,formatting data or some other data transmission in different levels of network.There will be security issues when the high security level network opens to the lower level.For example,when the critical data breaches from the high security level to the lower one,the invalid users can launch network attack from the lower security level to the high security level.A variety of firewall products are produced and used very well to prevent business information leakage.Firewall system can ensure that transferred data are confidential and controllable between the different security levels,however,the system is logic-based technology.Firewall system is likely to be attacked and hacked because of the certain security risks and loopholes in the Internet.In order to achieve higher security level transmission,physical isolation technology is needed.The design of data transmission system,which is based on unidirectional fiber transmission equipment,is an application of physical isolation transmission technology.For the unidirectional transmission of light,the transmission system uses optical transmitter and optical receiver to achieve one-way transmission of information.This thesis systematically introduces the background and application requirements of the data transmission system and explains the adaptive solutions that fit to users' needs.The specific design of the system is divided into hardware and software design.The hardware system is designed to introduce the composition of the whole hardware,especially the design of optical transmitter and optical receiver module.The software system is designed to introduce the functional modules of the entire transmission system,especially the one-way transmission module,state packet inspection(SPI)module,file type checking module and file import module.On the basis of systematical design,the hardware and software system are designed and implemented to form a one-way transmission system.The results of functional test and performance test,which are test on the one-way transmission system,show that all functions and performance index of the one-way transmission system meet the design target.