低信噪比下LFM- PRBC信号参数的快速估计

为了解决目前算法中线性调频-伪码（LFM- PRBC）信号参数估计计算量较大的问题，提出了一种快速估计算法。该算法采用解线调与分数阶傅里叶变换（FRFT）进行参数的估计。首先对信号进行解线调估计出调频斜率的粗略值，然后由调频斜率确定旋转角，通过FRFT估计出码元宽度的粗略值。根据延时再进行解线调估计出调频斜率的精确值，再通过FRFT估计出码元宽度的精确值与起始频率。该算法不仅计算量较低，同时具有很高的估计精度与很强的抗噪性，仿真实验验证了该算法的有效性。

Fast parameter estimation of LFM-PRBC signal under low SNR

To solve the problem that the parameter estimation of linear frequency modulation-pseudo random binary codes(LFM-PRBC) signal requires a large amount of computation in current algorithms,a fast parameter estimation algorithm which uses dechirp and fractional Fourier transform(FRFT) is proposed. Firstly,the dechirp is used to obtain the rough estimation of chirp rate which can determine the angle of rotation, and the rough estimation of symbol width is achieved by FRFT. And then,the exact value of chirp rate is estimated from the second dechirp based on the delay of the signal. Finally,through the second FRFT the exact value of symbol width and the initial frequency are obtained. The proposed algorithm has not only low computation complexity but also high estimation accuracy and strong ability of immunity to noise.The effectiveness of this algorithm is verified by simulation.