Processing Method Of Full-Wave Magnetic Resonance Sounding Signal Based On Adaptive Reference Cancellation

Water is one of the important and indispensable resources. At present, ourcountry faces two major problems, one is the lack of freshwater resources, and theother is the disaster-prone of groundwater sources. It is important significance for thedevelopment of human and environmental to accurately and easily determinegroundwater information. At present, the magnetic resonance sounding (MRS)detection method is the most direct, non-destructive geophysical methods among thedetection method for groundwater resources in the world. That detect groundwater bymagnetic resonance sounding of the proton in groundwater, and the advantages ofprobe results are quantitative and reconciliation unique. However, MRS signal isextremely weak, and the major limitation of the application of the method is sensitiveto electromagnetic noise, resulting in the noise of complex composition collected bythe high sensitivity of the receiving system and signal-to-noise ratio decreased,affecting the accuracy of the inversion results, and thus how to filter noise to extracteffective signal becomes critical.Aim at the bottleneck to obtain effectively full-wave magnetic resonancegroundwater detection signal under the strong noise interference for the in thefrequency harmonic interference, natural noise and occasional spike noise, researchmethod based on multi-channel adaptive noise cancellation suppress. Achievedetection channel and reference channel noise offset under different SNR throughintroduction of reference coils and establishment Adaptive Noise Cancellation (ANC)system of reference channel with90degrees phase shift by means of variable step size.Decomposed full-wave signal which have denoised into two orthogonal componentsusing digital quadrature algorithm, and then combined with the autocorrelation function and Least Absolute value nonlinear fitting to remove last unless unrelatednoise and extract the characteristic parameters that are initial amplitude and relaxationtime. Get the position and the water content of the underground aquifer and otherhydrogeological information by the inversion explain. Finally, verify the effectivenessof the denoise method by the measured data and drilling experiments.This study will solve the problem that difficult to effectively extract MRS signalunder the strong electromagnetic interference, provide a practical noise suppressionalgorithm, expanding the range of instrument application, and provide technicalsupport for the exploration and evaluation of water resources in China.