The Application Of Chaotic Oscillators In Weak Signal Detection

This paper is mainly to research the way of detecting the acoustic signals from the mine in the turbid maritime space. According to a large number of sand algae and plankton in the turbid sea area, the acoustic absorption coefficient is much higher than the area in the pure sea area. Furthermore, because of the request of the detection distance and the angle of incidence of the sound wave being less than the critical angle of the total reflection, only very small quantity of energy can enter into the seabed. After the sound comes into the seabed, the absorption of the sand is much more than that of the water. It's can be predicted that the echo of the objects is very weak.The thesis puts forward a new idea of weak signal detection based on the chaotic oscillators, and makes some elementary discusses about the problems in practice. The theory and experiments all prove the efficiency and the distinctive advantage of the approach.In chapter 1, firstly generally introduce the development of the chaotic theory. Then introduce the theory of the weak signal detection. Lastly, express the mainly work of this thesis.In chapter2, start from the mathematical model of the Duffing oscillator, and then analyze the Duffing system. We develop the expression of the bifurcation value with the Melnikov's Method, so we have a direct significance of how to choose the amplitude of the reference signal.In chapter3, construct the basic system of weak signal detection, and this base bring forward the approaches that use an array of chaotic oscillators to realize frequency scanning. And consummate this detection theory.In chapter4, analyze the statistical characteristics of the output noise from the Duffing system, which based on the theory of linear system and stochastic differential equation. Thereby make sure that the control ability about noise of this approach.In chapter5, aim at the instance in the practice, make same emulates to study the feasibility of this approach. And also get some useful conclusion.In chapter6, make some comparisons between this method and other signal detecting methods, then points out the advantage of this detecting approach. Finally, prospect the foreground of this method and the works to be done.