Research On Weak Signal Detection Based On Nonresonant Parametric Chaos Control

The detection of weak signal under the background of strong noise is a hot research direction of signal detection domain. Weak signals can be detected effectively using chaotic oscillator in conditions of a very low signal to noise ratio, where effective control of the chaotic oscillator is the premise. Chaos circuit will help the application of detection method with chaotic oscillator in engineering area. In this paper, a study on weak signal detection based on non-resonance parametric chaos control and chaos circuit design is carried out as follows:(1) The chaos control problem of Chen's system is studied based on non-resonance parametric driven chaos control method. A periodic signal whose frequency is far higher than the system's mean frequency is used as the input. And system variables of the controlled system are decomposed into slowly varying variables which change according to the system's mean frequency and fast varying variables which change according to the frequency of periodic signal. Then, by averaging method, a slowly varying dynamics is obtained. According to the dynamical characteristics of the slowly varying dynamics, the available control parameter range is obtained. Numerical simulation results show that this method can lead the controlled system to the target state rapidly, even when the control signal is disturbed by noise in certain SNR ranges. Therefore, feasibility of the proposed method is proved.(2) A weak signal detection model is builded based on Chen's system. Firstly, by averaging method, a slowly varying dynamics is obtained. Then, the parameter threshold which make the system from the periodic orbit to stable equillibrium point is obtained according to the dynamical characteristics of the slowly varying dynamics. By adjusting the testing parameters and observing changes in the system's status variables, the existence of the signal under test can be defined. Simulation results show that this method can effectively detect weak harmonic signals under strong noise background. Compared to other currently used methods of detecting weak signal based on chaotic oscillator, this method can precisely calculate critical values of the detected parameters through theoretical analysis, where the calculation is very simple and therefore suitable for popularization in relevant fields.(3) Based on the concept of chaos systems designing, a new three-dimensional quadratic autonomous chaos system is designed. The system's basic dynamic characteristics are analyzed with Lyapunov exponent spectrum and Lyapunov dimension of the system, and with bifurcation diagrams and Poincare section. Then, base on this new model of chaos system, the relationships of system parameters and circuit parameters are built after designing chaos circuits based on fundamental operation circuits and necessary circuit components. Then the circuit is simulated using Pspice, the simulation results of which verify the correctness of the analysis.Chaos system and circuit proposed in this paper and the exploration of the application of Chen's system in weak signal detection area is of application value in relevant fields.