MIMO雷达OFDM-LFM波形设计与实现

摘要

由于MIMO雷达发射相互正交的波形,因此正交波形设计是MIMO雷达实现的关键问题.针对MIMO雷达发射波形正交的特点,介绍了正交频分复用线性调频波形(OFDM-LFM)的设计原理.提出了一种正交频分线性调频波形产生的实现方案,该方案通过并行发射多路频分的线性调频信号形成OFDM-LFM波形.设计了一种由主控计算机、波形控制模块和数字中频合成模块构成的OFDM-LFM波形产生器.给出了基于AD9910数字斜坡调制方式产生单通道线性调频信号的方法和OSK功能产生多通道线性调频脉冲信号的方法,并对单通道线性调频信号线性度进行了分析.最后给出了其中两通道LFM信号频谱和一通道线性调频脉冲信号的时域波形的测试结果,验证了方案的正确性和可行性.%Waveform design is crucial for MIMO radar that transmits mutually orthogonal waveforms. Based on the characteristics of transmitted orthogonal waveforms, the design principles of the orthogonal frequency division multiplexing linear frequency modulationC OFDM-LFM) signals are introduced. In this paper a new realization scheme is presented where multi-channel frequency division linear frequency modulation signals are used to generate OFDM-LFM signals. We design a waveform generator composed of a host computer, a waveform control module, and a digital intermediate frequency synthesis module. The method for forming single-channel linear frequency modulation signal based on the digital ramp modulation mode of AD9910 and the method for forming multi-channel chirp signal based on the OSK function of AD9910 are introduced and the linearity of the single-channel LFM signal is analyzed. Finally, the experimental results of the two-channel LFM signal spectrum and the time domain waveform of one channel chirp signal are presented to verify the correctness and feasibility of the method.