短波通信中自适应均衡技术地研究.pdf

英文摘要III ABSTRACT With the characteristics of far transmission distance, simple structure and munication medium not being destroyed, munication is extensively applied in military and munication. In munication, the quality and speed munication are seriously affected by the intersymbol interference caused by multi-path transmission deriving from the characteristic of the channel. At present, the adaptive equalization is one of the main technical means to e multi-path effects and reduce inter-symbol interference, which essentially filter the received demodulated signal by adaptive filter. On the basis of analyzing characteristics of shortwave channel, this paper studies the advantages and problems of several equalizer algorithms and structures, and then conducts the function simulation of the LMS algorithm. The main work of this paper are as follow: Firstly, this paper introduces the application munication system and the history of Adaptive Algorithm briefly. The characteristics of shortwave and the reasons of intersymbol interference are studied. Based on the Nyquist theorem, the time domain equalization is described in details. This paper establishes the Watterson mathematical model of shortwave, and determines the channel’s parameters according to ITU-R. Secondly, this paper conducts extensive theoretical researches on several kinds of equalizer structures. Based on Watterson shortwave channel, this paper applies the least mean square algorithm and recursive least square algorithm, and conducts both theoretical research puter simulation to study the variables which influence the convergence rate, the tracking ability and the steady-state error of the algorithm. The simulation results proved that, in the same channel environment, compared with LMS algorithm, the RLS algorithm is one order of magnitude faster in the aspect of the convergence rate, and the effect of RLS algorithm is better in the aspect steady-state error. But, RLS algorithm’plexity is higher than LMS