Weak Signal Detection Based On Stochastic Resonance And Intrinsic Oscillation Of Nonlinear System

Stochastic resonance is the nonlinear phenomenon of cooperation between the input signal, the additional noise and nonlinear systems, in which part of noise energy can be transformed into signal energy. Stochastic resonance can improve output Signal-to-Noise ratio (SNR), so the weak signal detection method based on stochastic resonance can detect signal with lower SNR than the traditional linear signal detection methods.In this paper, taking a nonlinear monostable system with intrinsic oscillation as the research object, we study the relationship between the intrinsic oscillation and the monostable stochastic resonance. The result shows that the existence of intrinsic oscillation makes the nonlinear monostable system having frequency-selecting characteristic, which leads to the phenomenon of stochastic resonance in the nonlinear monostable system.Taking the weak signal detection based on monostable stochastic resonance as the starting point, we analyze the effects of the external input signal parameters and the system parameters on the performance of detecting weak signal in strong background noise. The results show that the frequency of intrinsic oscillation is determined by system parameters, as the stochastic resonance phenomenon of nonlinear monostable system is caused by intrinsic oscillation, the selections of system parameters will affect the stochastic resonance response of monostable system, and then affect the performance of weak signal detection; the monostable system's performance of weak signal detection is largely related with the external input signal amplitude and frequency, for certain nonlinear system, the system can not generate stochastic resonance phenomenon with improper parameter selection. The discussion about signal parameters and the system parameters will provide some reference for the selection and designing of weak signal detection system.Finally, we design a two-dimensional nonlinear system with intrinsic oscillation characteristic, then analyze and present the conditions which make the two-dimensional nonlinear system to be a monostable system, and we deduce the general expression of intrinsic oscillation frequency. We design a symmetric monostable system and a asymmetric monostable system with the the same frequency of intrinsic oscillation, then analyse and compare the frequency characteristic and the performance of weak signal detection about the two kind of systems. The results point out that,in the designing of weak signal detection system, we must choose suitable monostable system according to the the signal under test.Stochastic resonance has great potential in the application of signal detection, the study about the application of stochastic resonance is only just beginning, for us, there are many problems worth exploring.