Synchronization Key Technologies Of The Differential Frequency Hopping System

The Differential Frequency Hopping (DFH) Technology combines with modulation, coding and frequency hopping torganically, keeps the characteristics of interference of frequence hopping technology, enhances the the data transmission capacity greatly.The synchronization performance of DFH is a key indicator to measure the system performance of DFH, the traditional capture technology will be involved in Signal-to-Noise Ratio (SNR) threshold, but the SNR changes greatly in the real channel, especially in strong time-varying fading and strong interference channel, setting the best SNR threshold is very difficult; on the other hand, the capture probability is too low and false alarm probability is too high in traditional DFH system. For the shortcomings of traditional DFH synchronization system, we research and analysis DFH synchronization deeply.This article is divided into five chapters. The first chapter introduces the characteristics and development of short-wave frequency-hopping technology, and outlines the status of DFH technology research, focusing on the DFH Synchronization Technology Research; The second chapter combines the traditional capturing and tracking methods to analysis the shortcomings of traditional DFH synchronization, and gives the purpose of writing; The third chapter presents a DFH synchronization methord which based on soft desion, and studies the capture time, capture probability, false alarm probability in the AWGN and Rayleigh fading channel, and we simulated on the computer; The fourth chapter presents a code-aided DFH synchronization algorithm, including the acquisition methord based on m sequence and a tracking method based on Viterbi decoding, gives the principle, analysis the capture probility and false alarm probility theoretically and we simulated on the computer using Matlab. Since the window offset which based on Viterbi decoding has been affected greatly in the interference environment, this paper gives three kinds of non-linear processing program, the simulation shows that non-linear processing improves the tracking performance; Chapter five summarizes contributions of this paper and indicates the directions of further research.