DS/FH混合系统快速同步的研究

对于DS(Direct Sequence)/FH(Frequency Hopping)混合系统,提出了一种快速同步方案.同步包括捕获和跟踪两个阶段,在捕获阶段,利用快速频率识别方法对接收信号频率进行估计,实现混合系统的快速捕获;在跟踪阶段,根据获得的接收信号频率信息,等待在某一个特定的频率,通过直扩信号的捕获、跟踪、解调过程,获取接收信号的跳频同步信息,从而实现混合系统的快速同步.建立了DS/FH混合系统同步过程的数学模型,推导出采用该方案平均捕获时间表达式以及等待搜索同步法平均捕获时间计算公式.在高斯白噪声环境下,仿真结果证明了方案的有效性,在E_c/N₀=-15?dB时,通过合适的门限选取,混合系统的最小平均捕获时间可以缩短为一般常用等待搜索同步法的1/4.

Study on fast synchronization of hybrid DS/FH system

For a hybrid DS(direct sequence) /FH(frequency hopping) spread spectrum system,a fast synchronization method was proposed.Synchronization include two processes: acquisition and tracking.In the process of acquisition,a fast frequency identification method was used to realize the hybrid DS/FH systems' fast acquisition.In the process of tracking,based on the frequency information obtained,the receiver was waiting in a certain frequency.Through the DS signal's acquisition tracking and demodulation processing,to get the FH synchronization information,the hybrid DS/FH system's synchronization was completed.The mathematic model of the hybrid DS/FH system's synchronization process was provided,the mean acquisition time expression using this method and generalized mean acquisition time formula was derived.The validity of the project was verified after simulating,in the circumstances of Gauss noise,choosing the correct threshold,result at E_c/N_0=-15dB shows that the mean acquisition time is decreased almost 1/4 of the one using usual waiting method.