SNR Gain In Nonlinear Bistable Systems

Because Signal-to-Noise Ratio(SNR) is of importance to many engineering applications, such as in signal process and communication field, how to enlarge Signal’s SNR has been a hot research focus. Stochastic Resonance(SR) is regarded as a breakthrough point to get larger SNR Gain in the past several decades. Researchers have succeeded in enhancing SNR by using SR for some given kinds of signals. Sinusoidal signal is one of the most important kinds of signals in communication systems, and many systems use it as their carrier signal. Therefore how to enhance SNR of sine signal has realistic significance. In this thesis, we numerically studied how to improve sinusoidal signal’s SNR in bistable systems.In the first chapter, we present the realistic significance of improving SNR and some basic knowledge of stochastic resonance, and briefly summarize what researchers have already achieved.In the second chapter, we introduce definitions and algorithms of Power Spectral Density(PSD) and SNR, and some basic properties about bistable systems.The third chapter presents our own results. First we found that only a specific system can improve signals whose amplitude and intensity of noise are in a finite range. It is the monostability and nonlinearity that contribute to SNR enhancement rather than bistability. Next, due to the fact that the signal’s amplitude and noise intensity are always fixed in realistic and we could only adjust parameters of our nonlinear systems, we design an algorithm for better SNR. Finally, we point out some relevant problems.We summarize the whole article in the last chapter and present some problems that deserve continuing study.