The Research Of Atmospheric Laser Communcication System Based On Convolutional Code

Atmosphere Laser Communication refers to the technology of transmitting data using laser beam, it impressed many people communication area. It has advantages of wireless transmission and abundant bandwidth of fiber. So it has good application foreground in dissolve of "The Last Kilometer Problem". Atmospheric laser communication can be a good customer service to the complex environment of the difficulties, so it is in a standby emergency communications, military communications exhibit good transmission performance. Due to the restrictions of the laser communication, laser transmit power should be as low as possible with the premise of ensuring the correctness of communication. Compared with the conventional binary keying modulation manner, the optical pulse-position modulation can be largely solved the problems of the transmission power, so this modulation is applied to which atmospheric laser communication system. In the atmosphere Channel, there are a variety of weather conditions, the PPM modulation technology can not solve their laser communication generated interference, so we consider the use of the channel coding technology to reduce the impact of weather conditions brought on laser communication system error.Convolution code has been widely used in a variety of communication systems with good error correction capability. This paper is mainly in the analysis on the basis of the atmospheric random channel influence on laser communication, focuses on the convolutional code channel encoding technology for atmospheric laser communication, and discusses the feasibility of it to improve the system BER performance. The beginning of the paper explains the application of convolutional code in atmospheric laser communication system, design the system framework, do some related research and analysis.Next, analysis of the impact of atmospheric attenuation and atmospheric turbulence effects on communication. Simulate the atmospheric transmittance under different weather conditions. Propose a program to optimize the empirical formula.Research the impact of laser communication system BER in different turbulence environmental.In the paper, research the principles of the PPM modulation, the signal structure and demodulation scheme, uses the simulation method to research the transmission efficiency of PPM and OOK. Design the framework of the PPM modulation and demodulation system. The key simulation study is the performance of MPPM and PPM modulationAt last, do the research on the differences of punctured convolutional code and convolutional code, design an atmospheric laser communication system available for users to choose and analysis of the core circuit module.