In order to solve the problem that the existing Duffing chaotic circuit applies only to low-frequency weak signal detection, an improved circuit designed using actual electronic devices is presented. Through adjusting the parameters of the circuit, it could detect weak signal from low frequency to high frequency. In addition, by the Multisim simulation of the circuit at higher frequencies, its detection performance was studied. Experiments show that the circuit is very sensitive to initial values, and it changes its state from the chaotic state to the large-scale periodic state when the sinusoidal signal amplitude increases slightly. By adding thermal noise,the detection ability of the circuit under noise background was analyzed, meanwhile the signal to noise ratio(SNR) was obtained. Results show that with the increase in the accuracy of the critical threshold, namely the increase in detection accuracy, the SNR becomes lower and lower.%针对已有Duffing混沌电路仅适用于低频微弱信号检测的问题,提出一种改进Duffing混沌电路,并在虚拟电子工作平台(Multisim)软件中用实际电子器件实现了该电路.适当调整该电路的参数,可实现从低频到高频的微弱信号检测.另外,通过Multisim仿真,对该电路在较高频率下检测微弱信号的性能进行研究.仿真研究表明:该电路对初始值非常敏感,当正弦信号的幅值稍微增加,电路就发生混沌态到大尺度周期态的临界相变,可进行较高频率下的微弱信号检测.通过加入热噪声,分析电路在噪声背景下检测微弱信号的能力,并求取了信噪比.对仿真结果分析发现:随着临界阈值精确度的增加,也即检测精确度的增加,信噪比越来越低的现象.
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