M元正交扩频方案及其载波频偏估计算法

提出了一种M元正交扩频方案(MOSS:M-ary orthogonal spread spectrum)。按这种方式传输数据，发送信号不存在潜在的周期性，系统的抗干扰和抗截获性能得到了很好的保障。针对伪码较长、载波多普勒频移较大的接收机，传统的PMF-FFT同步捕获算法，进行的FFT点数较多，需要完成大量的复数乘加运算，捕获耗时长，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，提出了一种基于部分匹配滤波器和两级FFT的快速同步捕获算法（PMF-TLFFT），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，且计算复杂度显著降低。

M-ary Orthogonal Spread Spectrum and Estimation of Carrier Frequency Offset

A novel M-ary orthogonal spread spectrum is proposed In this paper. With this method, potential periodicity in the transmit signal is eliminated and the data is hard to detect or intercept with conventional technologies, thus the anti-jamming and anti-intercept capabilities of the system can be achieved. In order to overcome the difficulties incurred with long PN code spread spectrum system such as high computational complexity of synchronization and complicated hardware realization, a fast acquisition algorithm based on partial matched filters and two-leveled FFT(PMF-TLFFT) is proposed, which is capable of searching for the code synchronization point as well as estimating the carrier-frequency offset for correction, and it’s complexity is largely reduced compared with conventional PMF-FFT algorithm.