低信噪比下对称三角线性调频信号参数估计

低截获概率雷达的广泛应用导致电子侦察系统截获到的雷达信号大多处于低信噪比环境中。针对目前雷达信号参数估计算法在此环境中性能急剧下降,甚至失效的问题,提出一种基于多相滤波器组和高阶累积量联合处理的对称三角线性调频连续波信号参数估计算法。该算法利用多相滤波器组实现信号在频域上的快速均匀划分,对输出的每个子带信号进行三阶累积量对角切片的短时估计,有效抑制了高斯噪声的干扰,并经过包络检波后得到信号完整的时频矩阵,通过对时频图像进行Radon变换得到信号带宽、周期以及调频斜率的估计,频率曲线的提取得到信号起止频率的估计。仿真结果表明:方法在信噪比大于-12dB时的估计正确率较高。

Parameter estimation of STLFMCW signals in low SNR

With the extensive application of low probability of intercept(LPI)radars,most of the interception of radar signals is in low signal noise ratio(SNR).The performance of the common parameter estimation algorithms of radar signals is inevitably corrupted in low SNR.To estimate the parameters of symmetrical triangle linear frequency modulation continuous wave(STLFMCW)signals in low SNR,a novel method is proposed based on the poly-phase filter bank and high-order cumulant.Firstly,the poly-phase filter bank split the signal into many narrow frequency bands rapidly.Secondly,the Gaussian noise can be suppressed by using the short-time estimation of the third-order diagonal cumulant slices on each narrow frequency band.Then the estimation of the whole time-frequency matrixes can be obtained with envelope detection.Finally,the chirp rate,band width and period of STLFMCW signal can be estimated by radon transform of the time-frequency images.At the same time,the start-stop frequency can be estimated by extracting the frequency curves.Simulation results show that all parameters of the STLFMCW signals can be evaluated precisely when SNR is more than-12 dB.