Weak Signal Detection Theory And Extraction Arithmetic Study Based On Non-Linear System

Detecting weak signal from strong noise background is valuable in engineering field. Positioning of weak signal source plays very important role in fault detection and life-saving after disasters. Weak signal detection technology which is based on electronics, information theory, physics, statistics, etc., is to analyze principles and rules of the noise and study statistical characteristics and correlation of the measured signals and noise. Then it will exert a series of signal processing methods to control noise and detect the weak signal in strong background noise finally.By reading, experiments, comparing existent detection methods at home and abroad, and taking advantages of the new technologies brought about by computer science in weak signal detection, the author systematically studied weak signal detection theories and extraction methods. This dissertation focused on non-linear dynamical principles in signal detection, especially stochastic resonance. On the basis of studying stochastic resonance theory, aiming at explorer and study actual signals which are non-periodic impact signal and colored noise in engineering tests, this dissertation designed and implemented the adaptive weak signal extraction arithmetic based on stochastic resonance, then a weak signal detection simulation system in MATLAB has been designed, and the verification from a real recording file has testified its validity.The main research production and innovation of this dissertation are organized as follows:1. Through the studies on a lot of weak signal detection theories, especially modern detection methods, weak signal detection technology based on stochastic resonance has been introduced in this dissertation, and then the development and study status quo of the stochastic resonance has been summarized in details.2. Beginning at the two representational non-linear equations, which are Langevin equation and Fokker-Planck equation, this dissertation has introduced the basic principles of the two equations, and then used a lot of SIMULINK simulations to analyze and verify the basic theory of the stochastic resonance.3. As the ultimate goal of this dissertation is to study the weak signal detection in actual engineering practice, through the analysis on characteristics of actual signals, extraction of non-periodic impact signal from colored noise has been selected as the study object. The stochastic resonance effect of impact signal and colored noise through non-linear bistable system has been studied by a lot of simulations and experiments. This chapter is the theory basis of the arithmetic below.4. As the extraction of weak impact signal from strong colored noise is the study object, detailed design ideas and flow of adaptive weak signal detection arithmetic based on stochastic resonance has been discussed. This arithmetic has been realized mainly by adaptively tuning the system parameters or adding signal intensity to enhance stochastic resonance effect. At last, the arithmetic will be verified by ideal signals generated by MATLAB.5. According to the arithmetic designed above, a weak signal detection simulation system based on stochastic resonance, which is written by MATLAB scripts, is realized and applied to a practical recording sound file.