Shortwave Differential Frequency Hopping Communication System Multipath Processing Algorithms Research

HF frequency hopping is always one of the best options for emergency communications. DFH(Differential Frequency Hopping) system stands out because of its advanced modulation mode between all other frequency hopping communications and the rapid devolopment of DSP.But still DFH systems are facing the challenge of greater needs for stability and robustness.This article is based on DFH communication mode and researches the effects of multipath which leads to the thought of designing an algorithm to deal with it.According to the research progress and the contents in this paper, it is devided into three parts:Firstly, a brief analysis of the basic theory and research status of DFH is given, then the trend of DFH is summarized.Secondly, this article designed a simulation channel model specially for multipath situation in a DFH system after an analysis of the needs for system simulation and the models now are using. Besides designing all the models, this paper also finishs the setting of all the parameters.Thirdly, the multipath effects on system performance are further analyzed. According to this characteristic of a short-wave channel and the characteristics of a DFH system, a new multipath processing algorithm is designed. Then the simulation of this algorithm is run on computer with the platform of MATLAB and the results is shown latter with a further analysis.Lastly, after the simulation of the multipath processing algorithm,the main factors effecting the algrithm are analyzed and the importance of locating multipath in a multipath processing algorithm is clear. Then it comes to some ideas for further study and the works which should be done latter.