High-frequency Stochastic Resonance In Signal Detection,

The principle of Stochastic Resonance (SR) shows that obvious SR phenomenon can be observed at the output for signals with small parameters according to adiabatic approximation theory. Small parameters mean that the amplitude and frequency of period signal and noise intensity are all far less than 1. Stochastic resonance is a nonlinear effect that accounts for the optimum response of a dynamical system to an external forcing at a precise value of the noise intensity. The output signal-to-noise ratio (SNR) increases as the input noise intensity is increased over a certain range. The essence of the improvement of SNR is that the energy of noise is transformed into the signal energy. And the power spectrum of white noise changes in the structure after passing through the nonlinear bistable system. It is not the uniform distribution of energy any more, its energy focuses on the low frequency region in the form of Lorentzian. Therefore there is not enough energy for the Brown particle to get across the double-well potential at the high frequency region, and it's impossible to observe the phenomenon of SR. In other words, the detecting effect of stochastic resonance system is not obvious when the frequency of the weak signal is high.In order to deal with this problem, we take wide parameter input signal into consideration .This paper presents frequency shifting stochastic resonance. First, we shift the frequency of the input signal to a small one using the frequency shifting characteristic of Fourier transform, and then take advantage of the nonlinear cooperative effect of the bistable system to get the small frequency weak signal.The simulation results show that after shifting the input frequency to a small one, the output power spectrum peaks of the bistable system are strongly enhanced at this frequency. The ability of detecting weak signal overwhelmed in strong noise within a rather broad frequency range is improved in this way.