Research And Analysis Of Underwater Laser Timing Technology

For underwater environment,using wireless laser instead of traditional radio platform or acoustic time service can solve the problem of time delay and serious attenuation of radio or acoustic wave in underwater transmission.Underwater laser transmission has a stronger anti-interference ability,which is more conducive to the secret deployment of equipment,and faster and more reliable when completing information exchange.When the research target is underwater,wireless laser timing technology shows infinite potential and becomes a new direction of underwater timing research in the future.In this thesis,the existing problems of underwater laser timing technology are analyzed,the feasibility of underwater wireless laser timing technology is studied,and the key points and difficulties of underwater laser timing technology are clarified according to the current development of laser technology at home and abroad.In addition,an underwater laser timing model is established to analyze the jitter characteristics of the received signal of the underwater laser transmission terminal.Finally,the time jitter caused by the error rate of underwater laser transmission is analyzed and the modulation process is improved.The main contents of this paper are as follows:(1)In this thesis,the optical characteristics of sea water are studied,and the common research methods of laser transmission in sea water channel are introduced.The random phase screen method is used to simulate the underwater turbulent channel environment.The Born approximation and Rytov approximation of underwater laser transmission are used to solve the light intensity distribution at the receiving end and the amplitude of light field in sea turbulence,and then the expression of bit error rate is solved.(2)The channel model and the time jitter model of laser propagation in ocean turbulence are established.The time errors of laser propagation in underwater are analyzed.The simultaneous interpreting and calculating of the time jitter characteristics and the buffeting range of laser in different transmission distance,different turbulence types and different sea areas are carried out.(3)The performance of underwater laser communication is analyzed.This paper analyzes the impact of communication error rate on time error,analyzes the relationship between error rate and time jitter,improves and optimizes the OOK modulation form for the problems of high error rate and poor timing accuracy,and verifies the superiority and accuracy of the improved modulation form through comparison.In this thesis,the underwater laser timing model is established,and then the transmission time jitter characteristics of the underwater channel are studied,and the time jitter caused by the communication error rate to the received signal of the terminal is analyzed.According to the time jitter characteristics,an OOK modulation form is optimized and improved to reduce the time jitter caused by the error rate.The purpose of this study is to provide a reliable reference for future accurate sea surface tracking and underwater precise positioning and timing,which has a high research value.