【摘要】 针对超宽带(UWB)信号的超短脉冲和极低发射功率造成接收机同步十分困难的问题,提出了脉冲位置调制(PPM)下一种有数据辅助的基于"脏模板"定时(TDT)的同步捕获算法.推导了PPM调制下接收信号的表达式,分析了接收信号在相邻符号的互相关函数的特点.分析结果表明,不同于脉冲幅度调制(PAM)的互相关函数,由于PPM调制的非线性,同步参数不能通过对互相关函数求期望获得.构造相邻符号互相关函数的差值函数,借助训练序列来获取类似PAM调制情形下的互相关函数表达式,继而捕获同步.理论分析和仿真结果表明,该算法性能良好,捕获时间短,实现复杂度低.更多还原

【Abstract】 Due to the ultra-short information bearing pulses and the low transmitting power,ultra-wideband(UWB) receiver faces great challenge of timing acquisition.A data-aided timing acquisition algorithm was proposed for pulse position modulation(PPM) based on the synchronization criterion termed timing with dirty templates(TDT).The expression of the received PPM signal was deduced,and the cross-correlation function of nearby symbols was analyzed.The results show that different from that of pulse amplitude modulation(PAM),the cross-correlation function of PPM cannot be directly used to acquire timing due to the nonlinearity of PPM.Consequently,the algorithm adopted a simple training pattern based on the calculation of difference values of the cross-correlation function,which not only expedited the synchronization,but also enabled low implementing complexity.Simulations were performed to verify the theoretical analysis.更多还原