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Study On Weak Signal Detection Method Based On External Excitation Chaotic Oscillator

Posted on:2010-10-23Degree:DoctorType:Dissertation
Country:ChinaCandidate:T XieFull Text:PDF
GTID:1118360278952564Subject:Traffic Information Engineering & Control
Abstract/Summary:PDF Full Text Request
In the field of automation, communication, mechanical engineering etc, it is usually needed to judge whether the weak signals with special discipline appear. In the condition of intense environmental noise, the method of conventional linear filtering doesn't work any more. So it is an important task to find new detection methods. The chaotic system has the property of being sensitive to initial values and parameters, which hides the mechanism of sensing sensitive signals, especially the non-feedback perturbing control of chaos shows the sensitivity to special signals and immunity to noise, thus a new method for the weak signal detection technology is provided. This method has fundamental difference from conventional weak signal detection methods.This thesis performs deep and micromesh work in the key problems of chaotic oscillator detection system, which include analysis, output identification, noise immunity and constructive principle of chaotic oscillator detection system. And a new method of detecting weak periodic signals is proposed using the principle of producing intermittent chaotic signals in the chaotic oscillator detection system as a source of reference.The classification methods of chaotic detection system and chaotic oscillator detection system are put forward respectively according to the principle of detection system. The property of the Duffing-Holmes chaotic oscillator detection system is analyzed. Then the problem of signal detection with small frequency difference and of frequency jittering of pending signals in this detection system is researched. The result reveals that small frequency difference advantages stable output of intermittent chaotic signals, and a little bigger frequency jittering doesn't have an impact on the detection system. The property of the L-Y chaotic oscillator detection system is researched, and a kind of detection methods of this system is presented.In allusion to the output identification of chaotic oscillator detection system, the identification method of intermittent chaotic signals based on Poincare mapping is proposed on the basis of analyzing the noise property of Duffing-Holmes oscillator Poincare section. The method makes the rapid identification of intermittent chaotic signals in the chaotic oscillator detection system come true, and restrains effectively the impact of transient noise. In order to solve insufficient ability to restrain noise, a kind of difference Poincare mapping identification methods is further proposed that can achieve better performance of restraining noise. Thus the signal detection under lower Signal-to-Noise level is realized.How the noise in the external excitation chaotic oscillator detection system works is analyzed. The point that the global behavior of this detection system is necessary to the analysis of noise immunity is presented. Then generalized cell mapping is adopted to analyze the chaotic oscillator detection system. On the basis of global behavior, the noise immunity principle of the chaotic oscillator detection system is raised, and three constructive methods of detecting weak signals and the condition of producing intermittent chaotic signals in the detection system are put forward according to the L-Y chaotic oscillator detection system. Finally, the constructive principle of external excitation chaotic oscillator detection system is presented.Referring to how to produce intermittent chaotic signals in the chaotic oscillator detection system, a novel weak signal detection method based on outer orbit period region is proposed using the function that the Poincare section reconstructs signals and restrains noise, following which the modes of both large and small signals are given. Taking advantage of the characteristics that the output signal of detection system mentioned has very low frequency, detecting stochastic resonance weak signals with large parameters is successfully solved. Then the new method is further researched to analyze the feasibility that any Poincare section constructs detection system. And the effect the small chaotic area has on the detection method is also studied, the result of which indicates that small size chaotic attractor exists in the mode of large signal, but doesn't influence the detection system.
Keywords/Search Tags:Weak signal detection, Chaos, Duffing oscillator, External excitation system, System output identification, Noise immunity
PDF Full Text Request
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