The non-linear frequency modulation (NLFM) waveform is one of the existing waveforms that can be used in high range resolution radar applications. However, a high sampling frequency and consequently an expensive ADC are required. To overcome this drawback while taking advantage of the features of the NLFM waveform, we suggest approximating the wideband NLFM waveform by a piecewise linear waveform and using it in a stepped frequency (SF) framework. Thus, a variable chirp rate SF-LFM waveform is proposed where SF is combined with a train of LFM pulses having different chirp rates, durations, and bandwidths. In this paper, these parameters are derived from a tangent-based NLFM waveform. At the receiver, a generalized version of the time domain (TD) algorithm is proposed to process the received echoes. Our purpose is to obtain the high range resolution profile (HRRP) whose properties are of the same magnitude orders as those obtained using a tangent-based NLFM waveform. These properties are the peak sidelobe ratio, the integrated sidelobe, and the range resolution. Toward this goal, a multi-objective optimization issue is addressed to deduce the parameters of the proposed waveform by using two types of approaches based on evolutionary algorithms. Their relevance is compared. Our analysis and simulations show that the proposed approaches attain the targeted performance goals with a smaller sampling frequency at the receiver.

非线性频率调制（NLFM）波形是可以在高范围分辨率雷达应用中使用的现有波形之一。但是，需要高采样频率，因此需要昂贵的ADC。为了克服此缺点，同时利用NLFM波形的特征，我们建议通过分段线性波形近似宽带NLFM波形，并将其用于步进频率（SF）框架中。因此，提出了可变线性调频率SF-LFM波形，其中SF与具有不同线性调频率，持续时间和带宽的一系列LFM脉冲组合。在本文中，这些参数是从基于切线的NLFM波形导出的。在接收机处，提出了时域（TD）算法的通用版本来处理接收到的回波。我们的目的是获得高分辨分辨率轮廓（HRRP），其特性与使用基于切线的NLFM波形获得的数量级相同。这些属性是峰值旁瓣比，积分旁瓣和范围分辨率。为了实现这个目标，解决了一个多目标优化问题，通过使用两种基于进化算法的方法来推导所提出波形的参数。比较它们的相关性。我们的分析和仿真表明，所提出的方法在接收器处以较小的采样频率实现了目标性能目标。为了实现这个目标，解决了一个多目标优化问题，通过使用两种基于进化算法的方法来推导所提出波形的参数。比较它们的相关性。我们的分析和仿真表明，所提出的方法在接收器处以较小的采样频率实现了目标性能目标。为了实现这个目标，解决了一个多目标优化问题，通过使用两种基于进化算法的方法来推导所提出波形的参数。比较它们的相关性。我们的分析和仿真表明，所提出的方法在接收器处以较小的采样频率实现了目标性能目标。