基于NLFM的超低旁瓣脉冲压缩方法研究

在新型的天气雷达中,由于地面杂波反射强度能达到30~55dB,为了测量雨水强度,要求旁瓣电平小于60dB。相对于线性调频信号通过幅度加权得到低旁瓣输出,非线性调频信号(NLFM)无需加权就可以得到很低的主副瓣比,因此没有加权引起的信噪比损失和主瓣展宽等问题。但是对非线性调频信号直接匹配滤波只能获得-40dB左右的主副瓣比,无法满足天气雷达实际应用的需要,因此文中提出一种基于非线性调频信号的改进设计方法,仿真结果表明,该方法可以有效降低旁瓣电平,获得-73dB的主副瓣比,但也会引入一定的信噪比(SNR)损失。

An Ultra-Low Sidelobe Pulse Compression Method Based on Nonlinear Frequency Modulation Signal

In the modern weather radar,the echo of the ground clutter can reach 30-55 dB.So the nor-malized sidelobe must drop to -60 dB in order to measure the intensity of the rain.In contrast to the linear frequency modulation signal（LFM）,it must use amplitude weighting to lower the sidelobe level,so the per-formance of the nonlinear frequency modulation signal（NLFM）is good.The sidelobe level can achieve very low without window weighting,so there is no the loss of signal-to-noise ratio and the mainlobe width also should not be widened.But the result of the nonlinear frequency modulation signal can only reach -40 dB, which can not meet the requirements in applications.So other methods must be put forward.This paper pro-poses a new method to design NLFM,the simulation results show that this method can reduce the sidelobes effectively and the ratio of the mainlobe to the sidelobes can achieve -73 dB,but there is a loss of SNR.