Anti-saturation device and method for ground magnetic resonance signal amplifying circuit

Patent metadata

Field	Value
Publication number	US-10345474-B2
Application number	US-201715442430-A
Country	US
Kind code	B2
Filing date	Feb 24, 2017
Priority date	May 20, 2016
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

An anti-saturation device for a ground magnetic resonance signal amplifying circuit has a receiving coil connected with a band-pass filter circuit through a pre-amplifying circuit and a programmable amplifying circuit. The programmable amplifying circuit is connected with an AD acquisition card through the band-pass filter circuit. The band-pass filtering circuit is connected with a computer through the AD acquisition card, and the AD acquisition card is connected with an emitting system through the computer. An automatic amplification factor adjusting module is embedded into a nuclear magnetic resonance detector, and can also directly replace a receiving amplification circuit of the nuclear magnetic resonance detector to work independently.

First claim

What is claimed is:

1. An anti-saturation device for utilized with a ground nuclear magnetic resonance (NMR) signal amplifying circuit, the ground nuclear magnetic resonance signal amplifying circuit comprising:
a ground nuclear magnetic resonance receiving coil;
a pre-amplifying circuit;
a programmable amplifying circuit;
a band-pass filter circuit; and
an emitting system;

wherein the anti-saturation device comprises:
an analog-digital (AD) acquisition card;
a computer;
a micro control unit (MCU) control circuit; and
a level transition and electrical isolating circuit;
wherein the anti-saturation device utilized with the ground nuclear magnetic resonance signal amplifying circuit has the ground nuclear magnetic resonance receiving coil connected with the emitting system through the pre-amplifying circuit, the programmable amplifying circuit, the band-pass filter circuit, the AD acquisition card and the computer in the sequence listed;
the programmable control amplifying circuit is connected with the MCU control circuit through the electrical isolating circuit;
the MCU control circuit is connected with the computer;
the AD acquisition card comprises:
an analog-digital converter (ADC) module,
a level transition and electrical isolating circuit,
a field programmable gate array (FPGA) module,
a random access memory (RAM) module,
a read only memory (ROM) module,
a network interface and
a serial communication interface (SCI);

wherein the ADC module is connected with the FPGA module through the level transition and the electrical isolating circuit;
the RAM module is connected with the ROM module through the FPGA module;
the FPGA module is connected with the network interface and the SCI; and
the network interface and the SCI are connected with the computer,

whereby this configuration of components connected into the ground nuclear magnetic resonance amplification circuit forms the anti-saturation device because:
the ground nuclear magnetic resonance receiving coil is configured to induce ground magnetic resonance signals and transmit the ground magnetic resonance signals to the AD acquisition card through the pre-amplifying circuit, the programmable control amplifying circuit and the band-pass filter circuit;
the AD acquisition card is configured to perform a ground NMR acquisition in an acquisition time of 256 ms with 6400 sampling points;
the computer is configured to calculate a maximum absolute value V max among absolute values of 6400 acquisition points based on all signals collected by the AD acquisition card, and transmit the V max to the MCU control circuit;
the MCU control circuit is configured to:
a) compare the V max with the preset upper limit value and the preset lower limit value;
b) calculate the amplification factor for the next adjustment as: A i+1 =3.2*A i /V max , in order to reduce the amplification factor in a case that the V max is greater than the preset upper limit value V H , and increase the amplification factor in a case that the V max is less than the preset lower limit value V L , wherein the amplification factor for the present time is denoted as A i ;
c) select an adjusted magnification factor as the integer amplification factor which is nearest to and not greater than the amplification factor A i+1 from an arithmetic sequence from 2000 to 32000 with an equal difference of 2000, totaling 16 discrete integer point amplification factors;
d) set, through the level transition and electrical isolating circuit of the anti-saturation device, the amplification factor of the programmable amplifying circuit as the adjusted magnification factor, wherein the set amplification factor serves as the amplification factor for acquired signals for the next adjustment to the ground NMR acquisition occurring in time; and
e) transmit a complete instruction to the computer after setting the amplification factor; and

wherein the computer is further configured to control the emitting system to perform a next excitation.

2. An anti-saturation method compatible with an anti-saturation device that is utilized with a ground water nuclear magnetic resonance (NMR) signal amplifying circuit, comprising the steps of:
a) setting a programmable amplification factor, and an preset upper limit value V H and a preset lower limit value V L for overall signals manually based on an ambient noise intensity at a to-be-detected location before a nuclear magnetic resonance (NMR) ground water detection system starts working;
b) performing a ground water NMR acquisition in an acquisition time of 256 ms with 6400 sampling points, and calculating, by a computer, a maximum absolute value V max among absolute values of 6400 acquisition points based on all signals collected by an AD acquisition card;
c) obtaining an adjusted amplification factor, comprising:
transmitting the V max to a micro control unit (MCU) control circuit by the computer, wherein the amplification factor for the present time is denoted as A i ;
comparing, by the MCU control circuit, the V max with the preset upper limit value and the preset lower limit value; and
calculating the amplification factor for the next adjustment as: A i+1 =3.2*A i /V max , in order to reduce the amplification factor in a case that the V max is greater than the preset upper limit value V H , and increase the amplification factor in a case that the V max is less than the preset lower limit value V L ; and
selecting an adjusted magnification factor as the integer amplification factor which is nearest to and not greater than the amplification factor A i+1 from an arithmetic sequence from 2000 to 32000 with an equal difference of 2000, totaling 16 discrete integer point amplification factors;

d) setting the amplification factor of a programmable amplifying circuit as the adjusted magnification factor, by the MCU control circuit through a level transition and electrical isolating circuit, wherein the set amplification factor serves as the amplification factor for acquired signals for the next adjustment to the ground NMR acquisition occurring in time;
e) transmitting, by the MCU control circuit, a complete instruction to the computer after setting the amplification factor; and controlling, by the computer, the emitting system to perform a next excitation; and
f) repeating said step b) performing to step e) transmitting until stopping acquisition of the nuclear magnetic resonance signals.

Assignees

• Univ Jilin

Inventors

• Lin Tingting
• Zhang Yang
• Shu Xu
• Lin Jun
• Wan Ling
• Zhao Jing
• Cai Xin

Classifications

• G01V3/14 Primary

  operating with electron or nuclear magnetic resonance · CPC title

• G01R33/3614

  RF power amplifiers · CPC title

• Y02A90/344

  Cross-Sectional Technologies · mapped topic

• G01N24/081

  Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity · CPC title

• Y02A90/30

  Assessment of water resources · CPC title