Higher order stochastic resonance in a level-crossing detector

We investigate stochastic resonance in a simple level-crossing detector at the base frequency, as well as the higher harmonics, of a periodic stimulus . Using quadratic approximations, we observe a stochastic resonance phenome non with two maxims tin the presence of white Gaussian background noise) in the first harmonic at the output power spectral density of the system. Tha t means that there is an optimal strength of the input noise, where the sig nal transfer is the most linear, as the first harmonic is concerned. This u nique feature of this system cannot be found at the fundamental harmonic in the output. The theoretical results are confirmed by numerical simulations . This system is a good candidate for use in simple models of neurons, and other (nonlinear) signal detection systems. (C) 1999 Published by Elsevier Science B.V.