Study Of Weak Signal Detection And Processing Methods Under The Background Of Strong Noise

"Weak signal" not only means that the signal amplitude is very small, but mainly refers to the signal submerged by the noise."Weak" is relative to the noise. Weak signal detection under background of strong noise has been one of the challenges in the field of engineering application. In order to meet the needs of modern scientific research and technology application, the primary task of weak signal detection is to improve the signal-to-noise ratio so as to detect the useful weak signal from the strong noise. Therefore, the research of weak signal detection technology has important theoretical and practical significance.The subject comes from Inner Mongolia Autonomous Region Natural Science Foundation Project-"Study of weak signal detection and extraction technology under background of strong noise." For detecting weak signal under background of strong noise, the theory and methods of stochastic resonance are studied systematically. In the design of weak signal detection and processing hardware circuit which are based on modulated stochastic resonance, AD734four-quadrant analog multiplier chip produced by Analog Devices company is adopted to design modulation circuit and to achieve a signal mixer and stochastic resonance of the system. In that way, the high frequency signal is detected. The contents of this paper include the following aspects:①The detection and processing methods of weak signals and research status at home and abroad are introduced. This paper focuses on the history, current situation and development of the stochastic resonance nonlinear theory;②The stochastic resonance phenomenon of nonlinear systems is studied deeply. The relationship between the system structural parameters and the barrier or stochastic resonance is discussed in detail. The relationship between the noise, signal and nonlinear stochastic resonance system and conditions which cause stochastic resonance are also analyzed;③The method of modulating stochastic resonance is proposed by analyzing the stochastic resonance system. That is, the high frequency signal can be detected by using signal modulation method. The stochastic resonance method and chaos theory are combined to detect weak signals by comparing the advantages and disadvantages of them.④The circuit of modulated stochastic resonance system is designed according to the results of simulation. The structure and principle of modulation circuit and stochastic resonance circuit are introduced. The detection circuit of modulated stochastic resonance is build according to the design scheme.Based on the theory of stochastic resonance, weak signal detection and processing method under background of strong noise is studied in this paper. The hardware circuit is built according to the theoretical model of stochastic resonance. By analyzing and testing the circuit, experiments show that the system meets the expected target for and provides an implementation plan for the stochastic resonance theory applying in the engineering.