极低信噪比下对偶序列跳频信号的随机共振检测方法

针对对偶序列跳频(DSHF)在极低信噪比(SNR)下无法通信的问题，该文充分利用对偶序列跳频信号时、频域物理特征，提出一种随机共振(SR)检测方法，极大扩展该信号的应用场景。首先，通过分析对偶序列跳频的发射、接收信号及超外差解调的中频(IF)信号，构建随机共振系统，采用尺度变换调整中频信号；然后，引入判决时刻，将无定态解的非自治福克普朗克方程(FPE)转化为可解的自治方程，从而推导出含时间参量的概率密度周期定态解；其次，以最大后验概率为准则，得到检测概率、虚警概率和接收机工作特性(ROC)曲线；最后，得出以下结论:(1) 应用匹配随机共振检测对偶序列跳频信号的信噪比最低可达–18 dB；(2)对偶序列跳频与匹配随机共振结合，适用于信噪比在–18～–14 dB的信号检测；(3)应用匹配随机共振检测对偶序列跳频信号在信噪比为–14 dB时，检测性能提升了25.47%。仿真实验验证了理论的正确性。

Stochastic Resonance Detection Method for the Dual-Sequence Frequency Hopping Signal under Extremely Low Signal-to-Noise Radio

Considering the problem that the Dual-Sequence Frequency Hopping (DSFH) can not communicate at extremely low Signal-to-Noise Ratio (SNR), a Stochastic Resonance (SR) detection method is proposed. The SR takes full advantage of the physical characteristics of DSFH signal to improve the detection performance. Firstly, the SR is constructed by analyzing signals of transmission, reception and the Intermediate Frequency (IF). The scale transaction is used to adjust the IF signal to fit the SR. Secondly, the non-autonomous Fokker-Plank Equation (FPE) is transformed into an autonomous equation by introducing the decision time. Therefore, the analytical solution of the probability density function with the parameter of decision time is obtained. Finally, the detection probability, false alarm probability and Receiver Operating Characteristics (ROC) curve are obtained, when the criterion is the Maximum A Posterior probability (MAP). Simulation analysis results show three conclusions: (1) The SNR of DSFH signal can be as low as –18 dB, which uses the matched SR detection. (2) Method for combining DSFH with the matched SR is suitable to detect the signals with SNR of –18 ～–14 dB. (3) In the case of –14 dB SNR, the DFSH signal detection performance increases by 25.47%, when using SR. The proposed method effectiveness is proved with simulation results.