Research On Low Signal To Noise Ratio Signal Waveform Recovery Based On Chaos Theory

With the development of computer technology and communication technology,wireless communication，because of its low-cost, adaptable features，is widely used invarious fields, and has become one of the primary means to access and transmitinformation. In some environments, such as disaster areas, battlefield, the environmentof wireless communication is extremely harsh. The signal often drowned in the noise, soit is hard for the receiver to detect the useful signal, causing the communicationinterruption. The common signal detection methods generally have a high SNRthreshold for input signal, and sometimes are complex for its applications. Thesemethods can not meet the requirement of accessing to the signal conveniently andeffectively. Therefore, it is necessary to find a new low signal-to-noise ratio signaldetection method.In this paper, a method of low signal-to-ratio signal waveform recovery based onchaos theory has been studied. First, the dynamics of Duffing equation is analyzed, andit is found that the changes of dynamic behavior of Duffing equation are sensitive thechanges of the driving force amplitude. Then, Speed-Gradient method, an adaptivecontrol algorithm for chaotic synchronization, is introduced, and simulation experimentsshow that the method is effective on chaos synchronization. Finally a model for lowsignal-to-noise ratio signal waveform recovery is established based on chaossynchronization. This model consists of two Duffing systems controlled bySpeed-Gradient method. Using the model to recovery the waveform of the sinusoidalsignal and the BPSK signal with low signal to noise ratio, the simulation result showsthat the model can realize waveform recovery of signals which signal-to-noise ratio is-20dB.