M元正交扩频快速同步方法

Fast Synchronization for M-Ary Orthogonal Spread Spectrum

提出了一种M元正交扩频总体方案,按这种方式传输数据时,发送信号不存在潜在的周期性,数据难以被检测或截获,因此,系统的抗干扰和抗截获性能得到了很好的保障.当伪码较长、载波多普勒频移较大时,传统的同步捕获算法进行的FFT点数较多,复数乘加运算量大,耗时长,而在较长的捕获时间内,捕获得到的参数估计过于陈旧,无法应用于载波跟踪,为此,文中提出了一种改进的快速同步方法.该算法能在搜索出同步点位置的同时,有效估计载波频偏,进行频偏纠正,并且计算复杂度明显降低.

Proposed in this paper is a novel method of M-ary orthogonal spread spectrum, with which the potential periodicity of transmitted signals is eliminated and the data are hard to detect or intercept. Thus, both the anti-jamming and the anti-intercept capabilities of the system are well guaranteed. In the condition of long pseudo code and large carrier Doppler frequency shift, the number of FFT points in the conventional synchronous acquisition algorithm is too large, the complex multiplication is of high computational complexity and large time cost, and the parameter evaluation acquired in a long duration is not applicable for carrier tracking because it is too old. In order to solve these problems, an improved fast synchronous acquisition algorithm is proposed, which helps to search for the code synchronization point and estimate the cartier frequency offset for correction, with the computational complexity obviously reduced.