Method for removing peak noise in nuclear magnetism signal

Abstract

The invention relates to a method for removing peak noise in a nuclear magnetism signal, and the method is used for removing peak noise in a ground nuclear magnetic resonance underground water detection signal based on synchronization compression wavelet transformation and self-optimization non-linear threshold selection. The method comprises the steps: dividing the nuclear magnetism signal into a plurality of compression wavelet lengths; solving compressed wavelet coefficients of different compression wavelet domains; searching the position of the peak noise in the nuclear magnetism signal through employing a self-optimization algorithm, and removing the peak noise from the nuclear magnetism signal; carrying out the compensation for the nuclear magnetism signal where the peak noise is located through employing a non-linear threshold selection algorithm; and finally obtaining a final nuclear magnetism signal with the peak noise interference being removed through the compression wavelet reconstruction. The method will carry out the compensation of the nuclear magnetism signal where the peak noise is located while the peak noise is removed, and is effective for the removing of the peak noise mixed in a detection process of the nuclear magnetism signal.

Description

Technical field: [0001] The invention relates to a method for removing spike noise in nuclear magnetic signals, in particular to a method for removing spike noise in nuclear magnetic signals based on synchronous compression wavelet transform and a self-optimizing nonlinear threshold selection algorithm. Background technique: [0002] The total amount of water resources in my country is relatively rich, ranking sixth in the world, but the per capita water resources are only 1 / 4 of the world's per capita. The situation of fresh water resources is very grim. The NMR groundwater detection method is the only effective method used by hydrogeology and geophysics workers to directly detect groundwater. But the nuclear magnetic resonance signal is extremely weak, and the nuclear magnetic resonance detection instrument inevitably receives complex noise interference while receiving the nuclear magnetic resonance response signal. The complex noise interference makes the NMR groundwater...

AI Technical Summary

Problems solved by technology

While eliminating power frequency harmonic noise interference, the invention does not destroy any details of the signal, does not need to lay reference coils, is simple to operate, does not require a large amount of data to suppress random noise, and reduces processing time, but it also faces spike noise When it is mixed into the collected NMR data, the invention cannot effectively deal with the spike noise so that the final NMR data still has a low signal-to-noise ratio and cannot be used for inversion interpretation

[0004] The above-mentioned invention has a good effect on some noise mixed in nuclear magnetic data, but there is a shortage in the processing of spike noise. Because the spike noise has a much larger amplitude than the nuclear magnetic signal, it has a large range in both the frequency domain and the time domain. Therefore, it is very important to remove the spike noise mixed in the process of NMR detection of groundwater and to compensate the data disturbed by the spike noise.

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