Study Of Inversion Method For Tropospheric Radio Duct Transmission Characteristics

Tropospheric radio duct is an anomalous atmospheric structure. It widely occurs in theglobal ocean area and its appearance possibility is high. The tropospheric duct may make theradio waves above the ultrashort frequency propagate over the horizon and leads to theelectromagnetic blind area and so on. This greatly affects the performance of communication,radar and direction finding system. Recently, the times of local maritime disputes are not onlynoce around the surrounding waters of our country. And more and more attention is paid on theworld’s Ocean strategy. Hence carrying out the research of transmission characteristics oftropospheric duct thoroughly has important significance of theoretical guiding and practicalvalue.The main work is as follows:For the limitations of the existing commonly used research method on tropospheric ducttransmission characteristics, this paper proposes an inversion method based on the condition ofcommunication link to get the profile of transmission characteristics. Numbers of key issues inrespect of the methods involved in the forward model, inversion algorithm and efficiency areresearched. The conclusion not only enriches the tropospheric duct inversion ideas, but also hasgreat significance to improve the efficiency of existing research methods.For the problem of very simple model used in current inversion study, a certainwell-posedness inversion model is proposed. Forward simulation and analysis are carried on howthe horizontal inhomogeneous refractive index profile parameters affect the radio wave path loss.The main model parameters are extracted to build a tropospheric duct model on betterapplicability, and inversion simulation and test are carried out in chapter5. The given resultsshow that this study not only enhances the adaptability of inversion model, but also of greatsignificance for improving the inversion effect.For problem of limited global search capability and low efficiency in the existing researchon tropospheric duct properties inversion, combined with the transmission characteristics of thetropospheric waveguide. Applying particle swarm algorithm to achieve inversion is researched.The simulation and analysis are carried out using widely used simulated annealing and rarelyused particle swarm optimization and ant colony algorithm in the field of tropospheric ductinversion. And the results showed that the particle swarm optimization has unique advantages onsolving such inverse problems. It can improve the retrieval accuracy without increasingcomputation time by reasonably choosing the location of receiving antenna and setting inversionoptimize parameters. For solving difficulties of non-posedness inversion problem, the inversion method of tworeceiving antenna locations is proposed for further improving the inversion of the troposphereduct properties. This article studies how to use the two receiving position to jointly inverse thepath loss using the information contained in the two places. For the joint inversion, the givenresults show that effectively combined the two receiving location path loss information byreasonably setting weighted objective function can improve the effect of inversion solution. Andit also explores whether the relative loss and distance between the two receiving locations wouldinfluence the inversion results.In summary, this paper carries out in-depth, detailed study on the tropospheric ductproperties inversion method and numbers of key issues, the resulting conclusion of the study oncommunication link inversion has not only important theoretical significance and practical value,but also can be applied directly to the forward calculation and inversion research on thetransmission characteristics on the conditions of the troposphere duct. It is also of greatsignificance for improving the researching efficiency and real-time performance, better adaptionto practical applications.