Stochastic resonance in bistable systems subject to signal and quasimonochromatic noise

A bistable system subject to a periodic signal and quasimonochromatic noise (narrow band) is investigated. The system is experimentally realized by a set of linear and nonlinear electric devices, and stochastic-resonance-like responses of the system to the input are found. Under the optimal match of the control parameters the signal-to-noise ratio of the output may be higher than that of the input by a factor of 10, if the signal-to-noise ratio is defined in terms of power spectra.