非均匀频率密度多载波新型雷达信号

在高超声速目标搜索应用中，要求雷达发射信号具有高分辨、低截获、高多普勒容限等特性。本文针对OFDM信号多普勒容限低的缺点，提出了一种非均匀频率密度多载波雷达信号以及基于NLFM信号频谱窗函数的子载波频率设计方法；采取理论分析及数值仿真方法，推导、计算了该信号的频谱特性及模糊函数特性，并与典型OFDM信号的有关特性进行了对比，得出结论:新信号具有多普勒容限大、无距离—多普勒耦合、带外衰减快以及时延自相关函数旁瓣低等优点，适合于宽带高分辨雷达对高速运动目标的搜索与检测。 

A New Non-uniform Frequency Density Multi-carrier Radar Signal

In hypersonic target searching application, the transmitted radar signal was required to have characteristics of high resolution, low probability of intercept (LPI) and high Doppler tolerance. In order to overcome the disadvantage of OFDM signal’s low Doppler tolerance, a new type of multi-carrier radar signal with non-uniform frequency density was proposed and the design method of subcarriers frequency based on NLFM signal’s spectrum window function was given. Under the condition of equal subcarrier bandwidth, its subcarriers’ spectrum had larger density at frequencies that need to be enhanced. At the same time, the distribution of the signal’s subcarriers with non-uniform frequency density had a significantly weighting effect on its overall spectrum. Theoretical analysis and numerical simulation were adopted to derive and compute the spectrum characteristics and ambiguity-function (AF) characteristics of the proposed signal, and the same characteristics of typical OFDM signal were compared. The results show that the new signal has advantages of higher Doppler tolerance, no range-Doppler coupling, faster out-of-band attenuation and lower side-lobe of time-delay autocorrelation function (ACF), which is suitable for wideband high resolution radar to search and detect high speed? target.