Alpha 稳定分布噪声下基于 L-DFT 的 LFM-BPSK 复合调制信号参数估计

摘要

针对现有的复合调制信号参数估计方法在 Alpha 稳定分布噪声中性能严重退化的问题，提出一种基于L-DFT（L-Filter-Based DFT）的线性调频与相位编码（Linear Frequency Modulation and Binary Phase Shift Keying，LFM-BPSK）复合调制信号参数估计方法。该方法首先定义了 L-DCFT（L-Filter Based Discrete Chirp-Fourier Transform），平方倍频法消除编码调相后，采用 L-DCFT 估计信号的起始频率和调制斜率；分析了循环自相关函数中脉冲出现概率增大的问题，提出了基于改进 L-DFT 和循环统计量的码速率估计方法。仿真结果表明，基于 L-DFT 的参数估计方法能有效抑制脉冲噪声，在强脉冲噪声中具有良好的参数估计性能。%In order to solve the problem that the existing parameter estimation algorithm for hybrid modulated signals significantly degrades under Alpha stable noise,an L-DFT (L-Filter-Based DFT)based algorithm for hybrid modulated signals with binary phase shift keying (BPSK)and linear frequency modulation (LFM)parameter estimation is proposed.Firstly,the definition of L-DCFT (L-Filter Based Discrete Chirp-Fourier Transformation)is given.Then,the square frequency doubling method is applied to eliminate the binary phase modulation of the reconstructed signals,the initial frequency and chirp rate are estimated with L-DCFT.The problem of the probability growth of pulses in cyclic autocorrelation is analyzed,and a symbol rate estimation algorithm based on the modified L-DFT and cyclic statistics is proposed.Simulation results show that the L-DFT based method can suppress impulse noise efficiently and it has a superior parametric estimation performance under heavier impulse noise.