线性调频-伪码调相复合信号的伪码盲估计新算法

A New Blind Estimation Algorithm for PN Code of Reconnaissance Signal Combined PRBC and LFM

针对线性调频-伪码调相复合信号的伪码估计问题,提出一种基于离散多项式相位变换和频谱搬移的伪码盲估计新算法。首先采用平方法消去伪码的相位突变,然后利用离散多项式相位变换估计调频斜率,利用估计的高精度调频斜率重构二阶指数项,对原复合信号进行解线调,再对解线调后的信号取实部从而可得正弦载波与伪码调相的复合信号,采用频谱搬移的方法可恢复出原伪码序列。仿真结果表明,该算法在信噪比大于等于3 dB时可正确估计出伪码,且性能随子脉冲个数的增加而改善,与FM-AM时频分析方法相比具有更好的估计效果。

A new algorithm is proposed to blindly estimate the pseudo noise（PN） code of reconnaissance signal combined pseudo- random binary phase code （PRBC）and linear frequency modulated（LFM）, which uses meth- ods of discrete polynomial- phase transform（DPT） and spectrum shifting. Firstly, the square of the received signal is computed to eliminate the phase mutation. Then, DPT is adopted to obtain chirp rate, which is used to reconstruct the second - order index. The original signal is multiplied by the conjugated second - order index to get a new compound signal. And then, the real part of the new compound signal is made of a sine carrier and the PRBC signal, the original pseudo - code sequence can be restored by the way of spectrum shifting. Simula- tion results show that the algorithm can correctly estimate PN code when the signal-to-noise ratio（SNR） is greater than or equal to 3 dB, and performance will be improved with the increase in the number of sub - pulse. It also has a better performance compared with FM - AM time - frequency analysis method.