Research Of Atmosphere Laser Emergency Communication System

With the development of communication technology, Atmosphere Laser Communication is researched and used widely by people. Owing to a series of characteristics, such as easy-motion and lay-line-facility, the atmosphere communication system can be used as not only the means in emergency bust also a copy of optical fiber communication.Atmosphere laser communication system for fiber communication is researched and designed in this paper. It would temporarily replace the fiber communication system when it is broken or blocked caused by accidents or add communication-capability is needed. This thesis carried through the following aspects:1) With the research situation of atmosphere laser communication technology at home and abroad and the features of fiber communication, the feasibility of the Atmosphere Laser communication as emergency communication is disussed. Then this paper proposes an scheme of atmosphere laser communication system for fiber communication, designs the digital emergency optic termination, the important part of the atmosphere laser communicaiotn system as emergency communication, and finally describes the function of each model of the digital emergency optic termination in detail.2) The circuit of pick-up-clock signal of the digital emergency optic termination is designed. To ensure the compatibility of the emergency communication system and meet to the demand of the different rate of the fiber system, the system takes the clock signal via DPLL based on CPLD technology in the recover circuit of the digital emergency optic termination. In the light of the different communication rate, the varities of circuit are adopted and the function is accomplished.3) By the description on the PPM theory of the atmosphere laser emergency communication system and the comparison to the L-PPM, DPPM and multiple pluse PPM, the thesis proposes the scheme of the L-PPM modulator and demodulator.With the advantages of big-capability, low-cost and easy-motion, the atmosphere laser emergency communication system will take on a new look in the short-distance and high-communicaiton rate network such as the entrance network.