Stochastic resonance offers the possibility of signal amplification by the addition of noise. This curious, interesting phenomenon has received considerable attention since the 1990s. Since such effect has the potential to improve the signal processing performance, intensive works have been done about this topic. One of the most effective implementations of stochastic resonance is in the Collins network, which can provide outstanding performance in that the network output consists of an amplified version of a weak, sub-threshold signal. In practical situations, the sub-threshold signal is easily buried in external noise from the environment. The present paper focuses on the discrete-time system (plus continuous-time system) and analyzes this situation to clarify the performance degradation of the amplification effect. As a countermeasure, we herein propose a novel delay network. The present analysis indicates that the proposed scheme produces an amplification effect in the presence of external noise. The results of the analysis are used to determine the condition for which the delay network is effective, and the results of an experimental evaluation verifies the validity of the analysis. 
Concept, analysis, and demonstration of a novel delay network exhibiting stochastic resonance induced by external noise