Application Of Nonlinear System Theory In Weak Signal Detection

Weak signal detection based on dynamic theory of non-linear systems is a new method developed in recent 20 years.It is applied in many fields such as radar system state detection,mechanical system fault diagnosis,wireless network communication and biomedical information extraction.At present,the research of weak signal detection based on the non-linear theory of chaotic oscillator mostly stays at the theoretical stage,while the corresponding circuit experiment research is less.The experimental study can not only verify the feasibility of the theory,but also provide experimental basis for determining the parameters of the diagnostic system and theoretical research.In this paper,based on Lorenz system and SD(Smooth and Discontinuous)oscillator dynamics model,the theoretical analysis of non-linear dynamics is carried out by using MATLAB software,and the parameters are identified and modified.Hence,the improved system(Lorenz-like identification system and SD identification system)are more suitable for weak signal detection.Using modularization idea,circuit design and simulation are carried out in Multisim software.Lorenz-like identification system circuit and SD identification system circuit are designed respectively.By analyzing the circuit simulation results of SD recognition system,the weak signal detection method is established based on the "transition" of chaotic and periodic states.And the weak signal detection method is established based on the number of attractors in the system diagram by analyzing the circuit simulation results of Lorenz-like recognition system.After that,the two detection circuits are combined and optimized with higher detection accuracy theoretically.On the basis of simulation,the PCB diagrams of Lorenz-like recognition system and SD recognition system are drawn by Altium Designer software.And then the PCB board is built and the corresponding non-linear dynamic experiments are carried out.By comparing the experimental results with the theoretical simulation results,it can be found that the experimental results are basically consistent with the theoretical analysis results,which verifies that the built nonlinear system has weak signal detection ability.