脉冲噪声下基于NAT函数的LFM信号参数估计

Parameter estimation of LFM signals based on NAT functions in impulsive noise

针对传统的线性调频(linear frequency modulation, LFM)信号参数估计方法在脉冲噪声环境中无法准确提取参数信息的问题,设计了两种非线性幅值变换函数(nonlinear amplitude transformation, NAT),即attenuation-NAT(A-NAT)函数与increasing bounded-NAT(IB-NAT)函数,推导证明了大幅值脉冲样本经A-NAT或IB-NAT变换后,存在有界的二阶统计量,且LFM信号变换后仅幅值发生变化,相位信息不变。对经过NAT变换后的含噪信号进行吕氏分布(Lv’s distribution, LVD)分析,根据LVD域的峰值坐标即可实现LFM信号的参数估计。由实验结果可知,所提方法无需获取噪声先验信息,在强脉冲噪声条件下,仍可准确提取信号参数信息,具有良好的鲁棒性。

To address the problem of performance degradation or even failure of traditional linear frequency modulation signal(LFM) parameter estimation methods under impulsive noise, this paper constructs two new nonlinear amplitude transformation(NAT) functions, namely the attenuation-NAT(A-NAT) function and the increasing bounded-NAT(IB-NAT) function. The derivation proves that the second-order moments of the large amplitude pulse samples are bounded by A-NAT or IB-NAT. Moreover, only the amplitude of the LFM signal changes after the proposed transformation, and the phase information remains unchanged. Perform Lv’s distribution(LVD) analysis on the noisy signal after NAT transformation, and the parameter estimates of the LFM signal could be obtained based on the peak coordinates. Experimental results show that the proposed methods are robust, and they do not need the prior information of the impulsive noise, and can still accurately extract the signal parameter information even under strong impulse noise conditions.