Study On Weak Signal Detection Based On Van Der Pol-Duffing Oscillators

Weak signal detection is needed in many fields such as electronic engineering,biomedical engineering,communication radar and speech processing.Since weak signals are usually mixed with strong noise and the amplitude is very low,weak signal detection becomes the primary problem to be solved in the field of modern information technology processing.At present,the common weak signal detection methods have some difficulties in detecting weak signal with low SNR,however,the chaos detection method uses the sensitivity of the chaotic oscillator to the weak signal and the immunity to the noise to realize the detection of the weak signal,compared with the traditional methods,the SNR threshold is greatly reduced and the detection accuracy is improved.Firstly,the development of chaos theory,current cituation of weak signal detection technology and the application situation of chaos theory in the field of signal processing are introduced in this paper.The chaotic oscillators used in this paper(Duffing oscillator and Van der Pol-Duffing oscillator)are briefly described,then Duffing oscillator and Van der Pol-Duffing oscillator are coupled to establish a coupled detection system.Aiming at the critical threshold of the system,a method combining bifurcation diagram and dichotomy is proposed to search.In order to be able to detect weak signals of different frequencies,the system is transformed on a time scale.For single weak sinusoidal signal and mixed weak sinusoidal signals and weak sinusoidal signals submerged in colored noise,the coupled system is able to detect them well.Secondly,the coupled Van der Pol-Duffing system is established in this paper,and the dynamic behavior of the coupled system is compared under two sets of system parameters.Using the system to detect weak signals has achieved better results and reduced the SNR threshold.When the weak sinusoidal signals have different frequencies and phases to the reference signal,the impact on detection is discussed.Finally,the Van der Pol-Duffing oscillator is improved in this paper,on the basis of the original equation,?x~3 has been added,the simulation results show that the SNR threshold of the improved oscillator is reduced and the noise immunity is strengthened.In order to better detect weak periodic signals in strong noise,A united system based on Van der Pol-Duffing oscillator and cross-correlation is established.The simulation results show that the united system further reduces the SNR threshold,immunity to noise is also further enhanced.