混沌相位频率调制OFDM雷达信号研究

Research on Chaotic Phase Frequency Modulated OFDM Radar Signal

雷达波形设计逐渐成为现代雷达领域研究的热点,本文首先提出一种OFDM(Orthogonal Frequency Division Multiplexing,正交频分复用)混沌随机相位编码信号,并在此基础上用混沌序列对子载波进行频率调制,得到一种OFDM随机相位随机频率编码雷达信号形式,分析该信号的模糊函数、自相关特性以及子载波数对自相关性能的影响。同时,对该混沌编码信号存在的问题进行分析,并研究降低PMEPR(Peak to Mean Envelope Power Ratio,包络峰均比)的方法。仿真结果表明:基于混沌序列的OFDM相位频率组合调制信号具有更优的模糊函数和自相关旁瓣,混沌序列的复杂性和随机性使得信号具有更强的低截获特性。

Radar waveform design is becoming a research focus in the field of radar. First, this paper puts forward a kind of OFDM （ Orthogonal Frequency Division Multiplexing） chaotic random phase coded signal, on the basis of this signal, using a chaotic sequence to modulate the frequency of each sub-carrier in OFDM and produce a kind of OFDM radar signal form with random phase and frequency, then analysis this radar signal ambiguity function, auto-correlation and the influ- ence of its sub-carrier number. Analysis the problems of this chaotic coded signal and study the method how to reduce its PMEPR （Peak to Mean Envelope Power Ratio）. Simulation results show that the phase and frequency joint modulation OFDM coded signal has the better ambiguity function and auto-correlation side-lobe. Due to the complexity and randomness of chaotic sequences, the signal has the better low probability interception.