Weak Signal Detection Method Based On Chaotic Oscillator

The application of Chaos theory to weak signal detection is a creationary research, which extends the application field of Chaos theory and impels the development of weak signal detection theory. This dissertation makes a deeply research on weak signals detection using different chaos oscillators such as Duffing systems and Lorenz systems, getting hold of the effective detection methods in low SNR. What's more, those methods are analyzed detailed and theoretically and computer simulations show the validities of those methods. The contents of this dissertation are summarized as following:1. Introduce some theory knowledge on chaos oscillators, including a few basic concepts of dynamic systems and three means judging chaos phenomenon: Numerical value method, Lyapunov method and Melnikov method. That is a prerequisite step for analyzing chaos systems.2. Analyze complicated dynamic behavior of Duffing systems in detail, prove the chaos characteristic of Duffing systems using Melnikov method and judge its dynamic behavior using Numerical value method clearly. Deeply analyze the influence of noise intensity and the system's critical value on detection performance and fix its critical value scientifically.3. Making a deep research on weak sinusoid signal detection using Duffing Oscillators and combining chaos critical state detection method with general detection methods, this dissertation realizes weak sinusoid signal detection below -50dB SNR. Furthermore, starting from the analysis of the intermittent chaotic motion occurring in the detecting process, an array of Duffing Oscillators are used to estimate the frequency of weak sinusoid signals accurately.4. DSSS signal buried in the intensive noise environment is first detected successfully using Duffing Oscillators. Based on chaos critical state detection method, two approaches are used: One is that making a pretreatment on DSSS signal to take out the period information of the signal. The other is that starting from the analysis of the sensitivity of Duffing system to ambi-polar square wave modulated by sine signal, the...