针对Chirp基调制信号在分数阶傅里叶变换域特征明显，信号周期易被检测等问题，提出一种能够实现多域隐蔽的低检测概率(low probability of detection，LPD)波形构造方法。该方法采用分数阶傅里叶变换跳频(fractional Fourier transform-frequency hopping，FrFT-FH)架构，在不改变 Chirp 信号扩频增益的前提下，通过时宽分割和重组(time width division and reorganization，TDR)，降低信号在分数阶傅里叶变换域和周期域的能量聚敛特性。仿真结果表明，相较于现有LPD波形只能实现单一特征域隐蔽的问题，所提波形在不影响系统通信性能的前提下，面对频域检测、分数阶傅里叶变换域检测、周期域检测多种检测手段，在10 dB信噪比条件下的信号检测概率均低于0。2，满足系统在不同特征域下的LPD需求。
Design and performance analysis of LPD communication waveform based on FrFT-FH structure
In order to solve the problem that the Chirp signal has obvious characteristics in fractional Fourier transform domain and the signal's period is easy to be detected,a low probability of detection(LPD)waveform construction method that can achieve multiple domain concealment is designed.The proposed method refers to fractional Fourier transform frequency hopping(FrFT-FH)architecture without changing the spread spectrum gain of Chirp signal.Through time width division and reorganization(TDR),the convergence property characteristic of Chirp signal in fractional Fourier transform domain and the periodic domain of the signal are reduced.The simulation results show that the proposed waveform which is preserving system's conmunication performance,achieves signal detecion probabilities below 0.2 in frequency detection,fractional Fourier transform domain detection,and periodic domains detection with the condition of signal-to-noise ratio of 10 dB.The proposed method addresses the limitaion of current LPD waveforms which are confined to concealment problem in a single feature domain,and meets the requirements for system in various feature domains.
multiple domain concealmentlow probability of detection(LPD)fractional Fourier transform-frequency hopping(FrFT-FH)time width division and reorganization(TDR)
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