CN206258596U - A kind of ground nuclear magnetic resonance sampling apparatus - Google Patents

A kind of ground nuclear magnetic resonance sampling apparatus Download PDF

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Publication number
CN206258596U
CN206258596U CN201621348576.8U CN201621348576U CN206258596U CN 206258596 U CN206258596 U CN 206258596U CN 201621348576 U CN201621348576 U CN 201621348576U CN 206258596 U CN206258596 U CN 206258596U
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China
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low
signal
noise
magnetic resonance
nuclear magnetic
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Expired - Fee Related
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CN201621348576.8U
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Chinese (zh)
Inventor
孙淑琴
王翀
李永彬
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Jilin University
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Jilin University
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Abstract

The utility model belongs to nuclear magnetic resonance apparatus preparation field, more particularly to a kind of ground nuclear magnetic resonance sampling apparatus, and the device includes:Coil, for receiving environment electromagnetic noise signal;Pre-low-noise amplifier, after being connected with coil, signal is amplified;Filter unit, its input connects the output end of pre-low-noise amplifier, and the signal to amplifying carries out frequency-selecting;Capture card, after its input channel is connected with the output of filter unit, data signal is converted into by noise signal through A/D;PC, is connected with the output channel of capture card, receives and store the signal of capture card collection;First DC/DC circuits, by 12V power supplys switch to 9V and export to pre-low-noise amplifier and filter unit power after being connected with power supply;2nd DC/DC circuits, switch to 5V and export to capture card after being connected with power supply by 12V power supplys.The utility model circuit is simple, and sample circuit internal noise is low, and because circuit can simply reduce volume, the equipment that can make volume very little is easy to carry.

Description

A kind of ground nuclear magnetic resonance sampling apparatus
Technical field
The utility model belongs to nuclear magnetic resonance apparatus preparation field, more particularly to a kind of ground nuclear magnetic resonance sampling apparatus.
Background technology
Ground nuclear magnetic resonance (SNMR) technology is a kind of new geophysical method, since being developed successfully, the hydrology, Many fields of geology are applied, and are currently a kind of science skill that uniquely can be used as directly finding deep phreatic water in the world Art.The electromagnetic field of artificial excitation is typically with using this quasi-instrument of SNMR technologies so that the proton in molecule forms macroscopic view Magnetic moment, under local geomagnetic field action, produces precessional motion, and its frequency is exactly Larmor frequency of the proton in earth's magnetic field, example If nuclear magnetic resonance water detector is exactly that the Larmor frequency of local Hydrogen Proton is detected.
Because NMR signal is very faint (usually nV grades), what is detected using the instrument based on this technology In environment, there are various electromagnetic noises (50Hz or 60Hz industrial frequency harmonic noises, spike noise, random noise etc.), can be to detection Instrument causes severe jamming, and even resulting in instrument cannot normal work.If user is not knowing the feelings of these electromagnetic noises Measuring point is just selected under condition, it is possible to a large amount of human and material resources and financial resources can be wasted.At this moment being accomplished by one can be to electromagnetism in environment The device that noise is measured and analyzed in advance, a kind of foundation is provided to determine that can the place carry out using for pertinent instruments. For CHINESE REGION, all between 1kHz to 3kHz, such as Changchun Larmor frequency is 2.326kHz to Larmor frequency.Cause This is mainly the noise signal between 1kHz to 3kHz is acquired and divided for ambient noise harvester of nuclear magnetic resonance Analysis.With the environment electromagnetic noise analyzer supporting with nuclear magnetic resonance water detector and Jilin Province, China university instrument of French IRIS companies As a example by the noise measuring instrument that science and electrical engineering institute JLMRS type water detectors team develop, present Noise Acquisition and point Analysis apparatus are all excessively huge, overall to carry not aspect, if one man operation, it is impossible to measured for a long time, so ground The internal noise that one problem for first having to solution of nuclear magnetic resonance Noise Acquisition and analytical equipment seeks to sample circuit subtracts The complexity of circuit is used to minimum and reduction.
Utility model content
Technical problem to be solved in the utility model is to provide a kind of ground nuclear magnetic resonance sampling apparatus, circuit letter Single, sample circuit internal noise is low.
The utility model is achieved in that a kind of ground nuclear magnetic resonance sampling apparatus, and the device includes:
Coil, for receiving environment electromagnetic noise signal;
Pre-low-noise amplifier, after being connected with coil, signal is amplified;
Filter unit, its input connects the output end of pre-low-noise amplifier, and the signal to amplifying carries out frequency-selecting;
Capture card, after its input channel is connected with the output of filter unit, digital letter is converted into by noise signal through A/D Number;
PC, the output channel with the capture card is connected, and receives and store the signal of capture card collection;
First DC/DC circuits, switch to 9V and export to pre-low-noise amplifier and filter after being connected with power supply by 12V power supplys Ripple unit is powered;
2nd DC/DC circuits, switch to 5V and export to capture card after being connected with power supply by 12V power supplys.
Further:The annular enamel wire coil that the outer layer of the coil is encapsulated with white plastic, the Zhou Changwei of each circle 1.885m, the area of each circle is 0.2827m2, the circle insulated wire of coil periphery one, insulated wire one end connects 330 Ω small resistors, makees It is exciting signal source, is external to the passage of dynamic signal analyzer.
Further:The pre-low-noise amplifier is using three low-noise operational amplifier wired in parallel shapes of LT1028 models Low-noise operational amplifier block coupled in series after into preamplifier again with a LT1028 model is formed.
Further:The filter unit includes:The low-pass filter circuit being connected with the output of pre-low-noise amplifier And the high-pass filtering circuit being connected with the output of low-pass filter circuit, the low-pass filter circuit include model The first arithmetic device A1 of LT1885IS, the in-phase input end connection resistance R2 of the first arithmetic device, and be grounded by electric capacity C1, Output end is connected after the inverting input connection resistance R1 of the first arithmetic device and by adjustable resistance Rf1.
Further:The high-pass filtering circuit:Second arithmetic device A2 including model LT1885IS, second fortune The in-phase input end for calculating device A2 is input into by connecting electric capacity C2, and is grounded by resistance R4, the same phase of the second arithmetic device A2 Input is connected to output end after resistance R3 is grounded by adjustable resistance Rf2.
Further:The capture card uses Net0824 capture cards, including Ethernet interface, directly with the ether of PC Network interface is connected.
Compared with prior art, beneficial effect is the utility model:The utility model circuit is simple, inside sample circuit Noise is low, and because circuit can simply reduce volume, the equipment that can make volume very little is easy to carry.
Brief description of the drawings
Fig. 1 is the module frame chart of the sampling apparatus that the utility model embodiment is provided;
Fig. 2 is the circuit diagram of the pre-low-noise amplifier that the utility model embodiment is provided;
Fig. 3 is the circuit diagram of the filter unit that the utility model embodiment is provided.
Specific embodiment
In order that the purpose of this utility model, technical scheme and advantage become more apparent, below in conjunction with accompanying drawing and implementation Example, is further elaborated to the utility model.It should be appreciated that specific embodiment described herein is only used to explain The utility model, is not used to limit the utility model.
Referring to Fig. 1, ground nuclear magnetic resonance sampling apparatus, the device includes:Coil, for receiving environment electromagnetic noise letter Number;Pre-low-noise amplifier, after being connected with coil, signal is amplified;Filter unit, its input connects preposition low noise The output end of acoustic amplifier, the signal to amplifying carries out frequency-selecting;Capture card, its input channel is connected with the output of filter unit Afterwards, noise signal is converted into data signal through A/D;PC, the output channel with the capture card is connected, and receives and stores and adopts The signal of truck collection;First DC/DC circuits (photovoltaic conversion that existing module can be realized), by 12V electricity after being connected with power supply Source switchs to 9V and exports to pre-low-noise amplifier and filter unit power;(existing module can be realized 2nd DC/DC circuits Photovoltaic conversion), 12V power supplys are switched into 5V after being connected with power supply and are exported to capture card.
In view of the portability of device, the receiving coil for obtaining noise needs to meet light and handy, small size.For receiving For coil, the size that coil can receive signal is linear with effective area, therefore the bigger coil of effective area, institute The signal that can be received is bigger.But, the number of turn of coil again can not be too high, because the number of turn is too high, the distribution capacity meeting of coil Increase, so that the cut-off frequency of coil reduces, influences the reception of useful signal.
The coil that nuclear magnetic resonance water detector is used is 10000m2, ground nuclear magnetic resonance instrument work can be emulated in order to reach The purpose of the noise collected when making, the Noise Acquisition device receiving coil to be used of the present embodiment, its effective area 100m can not be less than2, and coil needs size small and be convenient for carrying, therefore annular enamel wire coil is employed,
The following is the call parameter of the receiving coil for measuring:
The annular enamel wire coil that outer layer is encapsulated with white plastic, measures to obtain diameter D=60cm, calculates the Zhou Changwei of each circle C=π × D=3.14159 × 0.6m=1.885m, the area of each circle is
Coil DCR=86.3 Ω are measured with LCR testers, it is 0.56mm to measure enamel-covered wire external diameter with slide measure, looks into money Material learns this kind of enamel-cover line standardThus coil total length L=86.3/0.0694=can be calculated 1243.5m, and then coil turn is calculated for N=1243.5/1.885=660, so coil total effective area is S0= 0.2827×660m2=186.6m2
With the inductance of LCR tester measuring coils, during f=1k, Ls=375mH;During f=10k, Ls=513mH.
The magnitude relationship of receiving coil resonant frequency tests line to the feasibility of signal acquisition with dynamic signal analyzer The attenuation characteristic of circle, finds its resonant frequency.Because outside noise is too big, therefore in coil periphery around a circle insulated wire, insulated wire One end connects 330 Ω small resistors, as exciting signal source, is connected to the passage 1 of dynamic signal analyzer, then connects Dynamic Signal The letter source ends of analyzer and passage 1, the two ends of receiving coil coil to be measured are connected to passage 2, are capable of achieving measuring coil The purpose of attenuation characteristic.Its peak is exactly the resonant frequency of receiving coil.
Referring to Fig. 2, before pre-low-noise amplifier is formed using the low-noise operational amplifier wired in parallel of three LT1028 models The low-noise operational amplifier block coupled in series after amplifier again with a LT1028 model is put to form.Due to by receiving coil be coupled into come Environment electromagnetic noise exist be receive volt level small voltage signal, so require that the equivalent input noise of preamplifier is enough It is low.
Select to be completed using low-noise operational amplifier module LT1028 in the present embodiment, have in 1kHz to 3kHz frequency ranges Preferable characteristic.
This amplifying circuit gain is 100 times, and the test of multiplication factor is completed with signal generator and digital oscilloscope, its What middle signal generator was given is the sine wave of " 2kHz, 100mVpp ", after preceding amplifying, accesses digital oscilloscope, is shown as The sinusoidal waveform of " 2kHz, 9.98Vpp ", changes the amplitude of the signal waveform that signal generator is given, repeatedly measurement, and test result is equal To amplify about 100 times.
Shown in Fig. 3, in order to obtain noise signal of the frequency range between 1kHz to 3kHz, the Noise Acquisition device needs One frequency selection circuit completes the selection of passband.Selection is built cut-off frequency and is existed respectively using two pieces of LT1885IS devices Low-pass filter circuit of the high-pass filtering circuit and cut-off frequency of 1kHz in 3kHz.Specifically:
Filter unit includes:The low-pass filter circuit being connected with the output of pre-low-noise amplifier (Fig. 3 is represented with A) And the high-pass filtering circuit that is connected with the output of low-pass filter circuit, low-pass filter circuit includes model LT1885IS First arithmetic device A1, the in-phase input end connection resistance R2 of first arithmetic device, and be grounded by electric capacity C1, the first arithmetic device Inverting input connection resistance R1 after and by adjustable resistance Rf1 connection output ends.
High-pass filtering circuit:Second arithmetic device A2 including model LT1885IS, the homophase input of second arithmetic device A2 End is input into by connecting electric capacity C2, and is grounded by resistance R4, and the in-phase input end of the second arithmetic device A2 passes through resistance R3 After ground connection, output end is connected to by adjustable resistance Rf2.
Pre-low-noise amplifier and filter unit are put together, integration test, test equipment is dynamic signal analysis Instrument.Test result display maximum gain is 1426, and now frequency is in 2.0kHz, and is in Changchun Larmor frequently in frequency During rate 2.326kHz, overall gain is 1398, and passband is 1.3kHz to 3.1kHz.
Capture card uses Net0824 capture cards, including Ethernet interface, is directly connected with the Ethernet interface of PC. The power supply of Net824 capture cards, DC+5V power input anodes, voltage range DC4.5V-5.5V, Overall Power Consumption 6.5W.
Preferred embodiment of the present utility model is the foregoing is only, is not used to limit the utility model, it is all at this Any modification, equivalent and improvement made within the spirit and principle of utility model etc., should be included in the utility model Protection domain within.

Claims (6)

1. a kind of ground nuclear magnetic resonance sampling apparatus, it is characterised in that the device includes:
Coil, for receiving environment electromagnetic noise signal;
Pre-low-noise amplifier, after being connected with coil, signal is amplified;
Filter unit, its input connects the output end of pre-low-noise amplifier, and the signal to amplifying carries out frequency-selecting;
Capture card, after its input channel is connected with the output of filter unit, data signal is converted into by noise signal through A/D;
PC, the output channel with the capture card is connected, and receives and store the signal of capture card collection;
First DC/DC circuits, switch to 9V and export single to pre-low-noise amplifier and filtering after being connected with power supply by 12V power supplys Unit's power supply;
2nd DC/DC circuits, switch to 5V and export to capture card after being connected with power supply by 12V power supplys.
2. ground nuclear magnetic resonance sampling apparatus as claimed in claim 1, it is characterised in that
The annular enamel wire coil that the outer layer of the coil is encapsulated with white plastic, the Zhou Changwei 1.885m of each circle, each circle Area be 0.2827m2, the circle insulated wire of coil periphery one, insulated wire one end connects 330 Ω small resistors, as exciting signal source, It is external to the passage of dynamic signal analyzer.
3. ground nuclear magnetic resonance sampling apparatus as claimed in claim 1, it is characterised in that the pre-low-noise amplifier is adopted With the low-noise operational amplifier wired in parallel of three LT1028 models formed after preamplifiers again with a low noise for LT1028 models Sound amplifier block coupled in series is formed.
4. ground nuclear magnetic resonance sampling apparatus as claimed in claim 1, it is characterised in that the filter unit includes:With it is preceding The high pass filter for setting low the low-pass filter circuit of the output connection of noise amplifier and being connected with the output of low-pass filter circuit Wave circuit, the low-pass filter circuit includes the first arithmetic device A1 of model LT1885IS, the same phase of the first arithmetic device Input connects resistance R2, and is grounded by electric capacity C1, after the inverting input connection resistance R1 of the first arithmetic device and leads to Cross adjustable resistance Rf1 connection output ends.
5. ground nuclear magnetic resonance sampling apparatus as claimed in claim 4, it is characterised in that the high-pass filtering circuit:Including The in-phase input end of the second arithmetic device A2, the second arithmetic device A2 of model LT1885IS is input into by connecting electric capacity C2, And be grounded by resistance R4, the in-phase input end of the second arithmetic device A2 after resistance R3 is grounded, by adjustable resistance Rf2 It is connected to output end.
6. ground nuclear magnetic resonance sampling apparatus as claimed in claim 4, it is characterised in that the capture card uses Net0824 Capture card, including Ethernet interface, are directly connected with the Ethernet interface of PC.
CN201621348576.8U 2016-12-09 2016-12-09 A kind of ground nuclear magnetic resonance sampling apparatus Expired - Fee Related CN206258596U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201621348576.8U CN206258596U (en) 2016-12-09 2016-12-09 A kind of ground nuclear magnetic resonance sampling apparatus

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Application Number Priority Date Filing Date Title
CN201621348576.8U CN206258596U (en) 2016-12-09 2016-12-09 A kind of ground nuclear magnetic resonance sampling apparatus

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110133559A (en) * 2019-05-21 2019-08-16 辽宁开普医疗系统有限公司 A kind of magnetic resonance B0 disturbance compensation systems and method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110133559A (en) * 2019-05-21 2019-08-16 辽宁开普医疗系统有限公司 A kind of magnetic resonance B0 disturbance compensation systems and method
CN110133559B (en) * 2019-05-21 2021-05-11 辽宁开普医疗系统有限公司 Magnetic resonance B0 field disturbance compensation system and method

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Granted publication date: 20170616

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