脉间频率编码脉内复合调频雷达信号设计与分析

现代的战场环境复杂多变，机载雷达除了需要具备较高的目标分辨力来完成目标探测任务外，还应具备大时间带宽积、低截获因子、低功率谱幅度、不均匀频谱及最大不确定性等良好的射频隐身性能。为了设计性能良好的射频隐身波形，本文以脉间脉内双重频率编码（interpulse Costas and intrapulse Costas，Costas-Costas）信号的时频特征为基础，在保持子脉冲间频率捷变的同时，在子脉冲内采用Costas频率编码和非线性调频相结合的复合调频方式，得到脉间频率编码脉内复合调频（interpulse Costas frequency coded and intrapulse Costas and NLFM composite frequency modulation，Costas-CN）雷达信号。与单一调制信号、脉间频率编码脉内非线性调频（interpulse Costas frequency coded and intrapulse nonlinear frequency modulation，Costas-NLFM）信号和Costas-Costas信号相比，该信号极大地增加了脉内调频特征的复杂性，增加了无源探测系统分选和识别的难度。仿真表明，Costas-CN信号在模糊函数、自相关特性、功率谱密度及截获因子等方面均有明显改善。在实现雷达探测的同时，该信号又具备良好的射频隐身性能，在现代战争中有广泛的应用前景。 

Design and Analysis of Interpulse Frequency Coded and Intrapulse Composite Frequency Modulation Radar Signal

? ?Modern battlefield environment was complex and changeable. In addition to having higher target resolutions to complete the target detection tasks， airborne radar should also have good Radio Frequency （RF） stealth performance such as large time-bandwidth product， low interception factor， low power spectrum amplitude， uneven spectrum and maximum uncertainty. In order to design well-performing RF stealth waveforms， based on the time-frequency characteristics of the interpulse Costas and intrapulse Costas （Costas-Costas） signal， while maintaining the frequency agility between the sub-pulses of Costas， the hybrid frequency modulation mode of Costas frequency coded and Nonlinear frequency was adopted in the sub-pulses and the interpulse Costas frequency coded and intrapulse Costas and NLFM composite frequency modulation （Costas-CN） radar signal was obtained. Compared to the single modulated signals， Costas-NLFM signal and Costas-Costas signal， Costas-CN signal greatly increased the complexity of the intrapulse frequency modulation features and increased the difficulty of sorting and identifying signals in passive detection systems. Simulations show that Costas-CN signal improved in ambiguity function， autocorrelation properties， power spectrum density and interception factors. While realizing radar detection， the signal also has good RF stealth performance， which has a wide application prospect in modern war.