De-noising For Noisy Chaotic Signal Based On Wavelet Transform

In the past few years, chaotic signal which are produced by a deterministic system have received a great deal of attention in many fields such as communication signal detection. In the process of the generation and transmission of chaotic signal, the existence of noise which mask the inherent dynamic characteristics of the system affects calculating the chaotic parameters. It follows that preprocessing the chaotic signals to reduce the noise without distorting the dynamics of the underlying signal is therefore of highly significance.This paper has devoted to the research of noise reduction of high frequency colpitts chaotic signals and its application. The new de-noising method is proposed and applied to the sidelobe suppression of chaotic radar range system. It mainly includes the following several parts:(1) From two aspects of wavelet form and threshold, wavelet transform is discussed that be used in the noise reduction of the high frequency Colpitts chaotic signal.(2) Based on the particle swarm optimization algorithm (POS) in lifting wavelet framework, a new chaotic noise reduction approach is proposed to improve the limit of wavelet threshold and wavelet form in the wavelet transform. White gaussian noise and colored gaussian noise which are embedded in chaotic signals are respectively applied for simulation analysis. This method solves the problem that the hard threshold function of the soft-threshold wavelet has a constant deviation in the application and that of the hard-threshold wavelet is not continuous, improve the noise ratio of the system and reduce the root mean square error.(3)From the theory of chaotic radar range system, wavelet transform and the new chaotic noise reduction are used for removing the noise in the experimental data of chaotic radar range system. The experimental results show that the precision and accuracy of radar ranging system are improved.In the theory, the new chaotic noise reduction is very effective in diminishing different kinds of noise, and performs better than the wavelet transform. In the practical application of the experiment of the chaotic radar range system, the new chaotic noise reduction has high value in the practical application.