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Method for filtering full-wave nuclear magnetic resonance signal noises based on double singular value decomposition

A singular value decomposition and nuclear magnetic resonance technology, which is applied in electron magnetic resonance/nuclear magnetic resonance detection, electric/magnetic exploration, acoustic re-radiation, etc., can solve problems such as effective extraction of MRS signals, and save manpower and material resources. The effect of improving timeliness

Inactive Publication Date: 2017-08-15
JILIN UNIV
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Problems solved by technology

[0008] The technical problem to be solved by the present invention is to provide a full-wave nuclear magnetic resonance signal noise filtering method based on double singular value decomposition to solve the effective extraction of MRS signals caused by strong power frequency harmonic interference and random noise in the magnetic resonance groundwater detection work The problem

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  • Method for filtering full-wave nuclear magnetic resonance signal noises based on double singular value decomposition
  • Method for filtering full-wave nuclear magnetic resonance signal noises based on double singular value decomposition
  • Method for filtering full-wave nuclear magnetic resonance signal noises based on double singular value decomposition

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Embodiment 1

[0086] This embodiment is a simulation experiment of the method of the present invention carried out under the MATLAB7.0 programming environment.

[0087] The simulation algorithm of the full-wave NMR signal noise filtering method based on double singular value decomposition, refer to the attached figure 1 , including the following steps:

[0088] Step (1): Use formula (1) to construct the initial amplitude e 0 =150nV, relaxation time Larmor frequency f = 2325Hz and phase For the ideal MRS signal, add -2dB Gaussian random noise and 6 power frequency harmonics with adjustable amplitude between 2200Hz and 2450Hz to the signal. At this time, the MRS signal is completely submerged in the noise and constitutes the observation data. The signal-to-noise ratio is -10.5271dB, such as figure 2 As shown in (a), figure 2 (b) Its corresponding frequency spectrum.

[0089] Step (2): Carry out band-rejection filtering centered on the Larmor frequency on the observed data to achieve...

Embodiment 2

[0095] This example is carried out in the Geological Palace of Jilin University in Changchun City. The MRS signal acquisition instrument used in this test is the "Nuclear Magnetic Resonance Array Receiver (JLMRS-ARRAY)" independently developed by Jilin University. The signal source is set to a frequency equal to 2326Hz. A full-wave MRS signal with an amplitude of 0.5V and a relaxation time of 180ms is transmitted through the transmitting coil. Keep a certain distance between the transmitting coil and the receiving coil to ensure that the receiving coil can couple MRS signals and environmental noise. as attached figure 1 As shown, the full-wave NMR signal noise filtering method based on double singular value decomposition includes the following steps:

[0096] Step (1): Use the ground NMR groundwater detection instrument to collect a set of observed MRS noise-containing data, SNR=-11.5324dB, such as Figure 6 (a) is the time-domain diagram of the observation data, Figure 6 ...

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Abstract

The invention relates to the field of noise filtering of nuclear magnetic resonance sounding signals, particularly to a method for filtering full-wave nuclear magnetic resonance signal noises based on double singular value decomposition. The method comprises: colleting one group of observation MRS noise-included data by using ground nuclear magnetic resonance underground water detection equipment; carrying out band-reject filtering using a Larmor frequency as a center on the data to realize preliminary signal and noise separation; carrying out first singular value decomposition and reconstructing noise data; subtracting the reconstructed noise data from the observation MRS noise-included data to obtain data including most of signal energy and reduced noise energy; carrying out secondary t singular value decomposition and reconstructing an MRS signal that need to be extracted; and carrying out MRS signal feature parameter extraction by using a non-linear fitting method. For full-wave MRS data collected by a single channel, influences of power-frequency harmonic interference and random noises can be eliminated simultaneously; and effective extraction of the MRS signal feature parameters can b realized by non-linear fitting.

Description

technical field [0001] The invention relates to the field of nuclear magnetic resonance sounding (Magnetic ResonanceSounding, MRS) signal noise filtering, in particular to a method for filtering full-wave nuclear magnetic resonance signal noise by using a double singular value decomposition method. Background technique [0002] Magnetic resonance sounding (magnetic resonance sounding, MRS) technology is currently the only geophysical prospecting method that directly and effectively detects groundwater. , can give quantitative explanations for the depth and thickness of the underground aquifer, the size of the water content, the porosity of the underground medium, etc., so it is widely used in the fields of water resource exploration, landslide geological disaster detection, mine water inrush and tunnel water inrush. Its basic principle is to realize the detection of groundwater by detecting the nuclear magnetic resonance signal generated by the resonance transition of hydrog...

Claims

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Application Information

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IPC IPC(8): G01V3/14G01V3/38
CPCG01V3/14G01V3/38
Inventor 田宝凤任华王超群蒋川东易晓峰朱慧刘建南
Owner JILIN UNIV
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