高动态环境二进制偏移载波调制信号的捕获

针对含一阶多普勒变化率的高动态二进制偏移载波（BOC， Binary Offset Carrier）调制信号捕获精度低且运算量大的问题，本文在部分匹配滤波器结合分数阶傅里叶变换（PMF-FRFT， Partially Matched Filter-Fractional Fourier Transform）算法的基础上提出使用分数阶功率谱累积结合分级FRFT的捕获算法。该算法首先利用PMF对信号进行分段处理，实现了接收信号和本地伪码之间的快速相关。然后结合线性调频信号（LFM， Linear frequency modulation signal）在不同FRFT域内的能量聚集特性，利用分级FRFT结合分数阶功率谱累积精确确定最优阶数。最后利用FRFT在所对应的最优阶数下结合分数阶功率谱累积实现对存在一阶多普勒变化率信号的精确捕获。仿真结果表明，该算法可以减小算法运算量，缩短捕获时间。且在功率谱累积20次，伪随机码长度为1023、信噪比为-22 dB左右的时候仍然能够实现精确的捕获。 

Acquisition of Binary Offset Carrier Modulation Signals in a Highly Dynamic Environment

? ?Aiming at the problem of low acquisition accuracy and large computation of the modulation signal of BOC （Binary Offset Carrier） with first-order Doppler rate， In this paper， a Partially Matched Filter combined with Fractional Fourier Transform （PMF-FRFT） algorithm is proposed， which used Fractional power spectrum accumulation combined with Fractional FRFT. In this algorithm， PMF was used to segment the signal， and the fast correlation between the received signal and the local pseudo-code was realized. Then combined with the energy aggregation characteristics of Linear Frequency modulation signal （LFM） in different FRFT domains， the fractional FRFT combined with fractional power spectrum accumulation was used to accurately determine the optimal order. Finally， FRFT was combined with fractional power spectrum accumulation in the corresponding optimal order to accurately capture the signal with the first order Doppler rate of change. Simulation results show that the algorithm can reduce the amount of computation and shorten the acquisition time. Moreover， when the power spectrum is accumulated 20 times， the accurate capture can still be achieved when the pseudo-random code length is 1023 and the SNR is about -22 dB.