Weak Signal Detection Of Stochastic Resonance Method And Applied Research

Stochastic resonance (SR) is a kind of nonlinear phenomenon, which can convert partial energy of noise into the energy of signal, and enhance the transmission of weak signal through the nonlinear system, it can detect signal with lower signal-to-noise ratio (SNR) than linear methods. Taking a nonlinear bistable system, and a strong background noise detection of weak signals actual needs as the starting point, on the basis of the previous comprehensive study of the stochastic resonance, study the relationship among stochastic resonance, the signal and noise systematically. The stochastic resonance phenomenon is thoroughly investigated in detail under the condition of small parameters, and the SR mechanism is analyzed from the structure of frequency spectrum. The applied research of stochastic resonance in the detection of weak signals has been probed into.The contents of this dissertation are summarized as following:(1)The history, status and development of SR have been introduced, the characteristic and current research methods of weak signal detection are summarized.The method of weak signal detection based on SR is discussed in-depth. The main problems of this method are pointed out.(2)The bistable system of nonlinear Langevin and the Fokker-Planck equation are introduced briefly, analysis for the study of nonlinear systems establish the foundation for stochastic resonance effect through the Langevin equation of stochastic resonance. The judgement of nonlinear systems turning into the stochastic resonance has an important indicator -SNR.(3)The nonlinear systems stochastic resonance effect is studied in depth, the relationship among structural parameters of the system, the barrier system and the stochastic resonance is researched in detailed. The relationship among the signal, noise and the nonlinear system is analyzed in-depth, and the systemic conditions for shochastic resonance. The relationship between stochastic resonance system and the best valuea is studied in detailed under the structure of the system parameters b = 1. (4)The stochastic resonance phenomenon created by cooperation of the three parts of the bistable system, noise and an input signal is thoroughly investigated in detail under the condition of small parameters. The SR mechanism is analyzed from the structure of frequency spectrum. The SR is comparatively more sensitive to the frequency of the input signal. Increasing the signal amplitude or decreasing the parameter value of the bistable system, i.e., reducing the potential barrier is benefit to make SR.(5)To solve such a problem met in engineering application frequently as detecting weak signal submerged in strong noise by means of the SR technique, in terms of the theory of small parameter SR, a novel method of Scale-transformation Stochastic Resonance(STSR) is adopted. With large parameters, the SR-like phenomenon may be brought, this is, a detected SR spectral spike at the signal frequency can be created.(6)Using stochastic resonance technology to weak signal detection, computer simulations prove that, the weak sine signal can be detected effectively in the background of strong noise, moreover, it can detect weak information below -15dB. The one-dimensional bistable Langevin systems and two-dimensional bistable Duffing system stochastic resonance phenomenon and its conditions are studied comprehensively and in-depth, and comparative analyze the performance of weak signal detection of the two systems, discuss the application of stochastic resonance.