Research on extraction method of tunnel magnetic resonance detection signal based on collaborative filtering

Abstract

Magnetic resonance detection of tunnel as a non-invasive, direct and quantitative geophysical method for detecting groundwater has attracted much attention in the research of tunnel water hazard early warning. In view of the complex environment where the magnetic resonance detection signal is only nanovolt and the tunnel space, the peak noise and environmental noise are much greater than those of ground magnetic resonance detection. In this paper, we propose a peak noise suppression method based on collaborative filtering to suppress the peak noise of tunnel magnetic resonance rotation detection. In this method, the co-filtering parameters are calculated by using the data without peak noise, and then the peak noise suppression of rotation detection is realized. Through simulation, this method can effectively suppress the peak noise in the tunnel rotation detection magnetic resonance signal and improve the signal quality without changing the relaxation and attenuation characteristics of the tunnel magnetic resonance detection signal. The noise reduction effect of peak noise suppression method based on collaborative filtering is compared and analyzed when the amplitude and quantity of peak noise are different. The influence of this method on the peak noise suppression effect under different Gaussian noise levels is discussed. It is concluded that collaborative filtering can suppress the peak and part of Gaussian noise well without losing the effective magnetic resonance signal.