Detection Of Weak Underwater Target Signal Based On Chaotic Oscillator

The technology of underwater signal detection has played significant theoretical and military roles in the national defense construction. The detection of low SNR underwater acoustic signal under complex ocean background interferences has been the hot point in the field of underwater acoustic signal processing. With the recent development of chaos theory, the underwater acoustic signal processing and detection based on the chaos theory has appealed to more attentions in underwater acoustics. And hence a number of useful research results have been obtained.In the paper, the detection of low SNR underwater acoustic signal based on chaos theory has been explored. The basic detection scheme and practical application of this new technology using Duffing equation have been put forward. Also a way of judging whether or not periodic signals exist in target signal based on the phase space portrait has been proposed. Some elementary discusses on the detection problems in practice have been presented. The main contribution of the paper is as follows:1. The chaotic oscillator detection system for mono frequency Sin and square signals is constructed. Several state space transferred with the varying of inner embedded signal amplitude have been analyzed. The Sin and square wave signals under the interference of white noise and color noise have been detected using the proposed detector. And the performance of detection under studying is analyzed2. The chaotic oscillator detection system for general periodic signal has been set up, and using the system we detect a kind of small periodic signal and impulse signal. The system's performance for both small periodic signal and impulse signal has been evaluated. It shows that the system has good detection effect on arbitrary periodic signals. This lay the good groundwork to detect actual signals future.3. Using the chaotic oscillator detection system to detect actual ship targets, we could distinguish effectively the periodic component in the ship target signals, and could get some good detection results.4. Some chaotic feature parameters of the underwater acoustic signal have been calculated. Using the Melnikov's function, we can find the critical value when the system is becoming to chaos. Meanwhile we calculate the system's Lyapunov exponent to effectively detect the boundary that the system goes from chaotic state to great scale...