二次调频-伪码调相复合信号的伪码盲估计

针对二次调频-伪码调相复合信号的伪码盲估计难题,提出一种基于三次相位函数和频谱搬移的伪码盲估计算法。首先利用平方法消去伪码和信息码的相位突变,针对平方法带来的噪声恶化问题,采用对三次相位函数累加平均的方法估计二、三阶系数,利用估计的高精度系数重构指数项,对原复合信号进行降阶,再对降阶后的信号取实部可得正弦载波与伪码调相的复合信号,最后采用频谱搬移的方法可恢复出原伪码序列。仿真结果表明,该算法具有可行性,当信噪比大于等于1 dB时,伪码估计的正确率大于0.9,表现出较好的性能。

Blind estimation for PN code of reconnaissance signal combined with quadratic frequency modulated and pseudo-random binary phase code

A new algorithm is proposed to blindly estimate the pseudo noise(PN) code of reconnaissance signal combined with quadratic frequency modulated(QFM) and pseudo-random binary phase code(PRBC),which is based on the methods of cubic phase function(CPF) and spectrum shifting.Firstly,square method is computed to eliminate the phase mutation,which induced noise degradation.Then,Method of CPF based on cumulative mean is adopted to estimate second and third coefficients,and the coefficients are used to reconstruct the index.The original signal is multiplied by the conjugated index to get a new compound signal.And then,the real part of the new compound signal consists of sine carrier and the PRBC signal,and the original PN code can be restored by the way of spectrum shifting.Simulation results show that the algorithm is feasible,and correct rate of PN code estimation is more than 0.9 when signal-to-noise ratio is more than or equal to 1 dB,which shows good performance.