Ground magnetic resonance signal detection device and detection method with automatic gain adjustment function

A magnetic resonance signal and automatic adjustment technology, which is applied in magnetic resonance measurement, detection by electronic magnetic resonance/nuclear magnetic resonance, measurement of magnetic variables, etc. , to achieve good matching of magnification, suppress amplifier saturation, and achieve the effect of precise synchronization

Active Publication Date: 2018-08-24
JILIN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The existing ground magnetic resonance signal detection device only manually adjusts the gain once according to the environmental noise, that is, the magnification factor is fixed during the entire measurement period
Since the noise will change greatly over time, two extreme situations often occur in this method of manually adjusting the fixed gain. One is that the gain is too small and the signal accuracy cannot meet the requirements; the other is that the gain is too large and the amplifier is saturated.
Especially in areas with severe interference, the signal is often submerged in the noise, and the amplifier is easily saturated due to the large interference noise, causing the magnetic resonance water detector to fail to work normally

Method used

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  • Ground magnetic resonance signal detection device and detection method with automatic gain adjustment function
  • Ground magnetic resonance signal detection device and detection method with automatic gain adjustment function

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Embodiment 1

[0030] In the electromagnetic shielding laboratory, taking a DC voltage of 0.23mV as the input and a sampling time of 256ms as an example, the application of the ground magnetic resonance signal detection device and detection method with automatic gain adjustment function is described.

[0031] The specific implementation steps are as follows:

[0032] a. Initial parameter setting: the sampling frequency of the pre-sampling ADC module 5 is set to 25kHz by the computer, the main sampling ADC module 6 is set as an external interrupt triggering sampling mode, and the initial magnification factor A=32000 is set;

[0033] b. Pre-sampling ADC acquisition signal: FPGA module 7 controls the pre-sampling ADC module 5 to convert the weak magnetic resonance signal into a digital signal after being amplified by the preamplifier circuit 1, which is the value V of the first sampling point p1 =0.46V, the amplification factor of the preamplifier is A p =2000;

[0034] c. Signal judgment: th...

Embodiment 2

[0041] In Shaoguo Town, Changchun, a magnetic resonance water detector integrating transceiver and signal detection device designed by the present invention is used to illustrate the application of the ground magnetic resonance signal detection device and detection method with automatic gain adjustment function.

[0042] The specific implementation steps are as follows:

[0043] a. Initial parameter setting: set the sampling frequency of the pre-sampling ADC module 5 through the computer, set the main sampling ADC module 6 as an external interrupt trigger sampling mode, and set the initialization magnification factor A;

[0044] b. Pre-sampling ADC acquisition signal: FPGA module 7 controls the pre-sampling ADC module 5 to convert the weak magnetic resonance signal into a digital signal V after being amplified by the pre-amplification circuit 1 pi , V pi is the value of the i-th sampling point, and the amplification factor of the preamplifier is A p ;

[0045] c. Signal jud...

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Abstract

The invention relates to a ground magnetic resonance signal detecting device with an automatic gain adjusting function, wherein a frontend amplifying circuit is connected with a narrowband filter circuit through a wideband bandpass filter circuit. The frontend amplifying circuit is connected with an FPGA module through a presampling ADC module. The narrowband filter circuit is connected with a main sampling ADC module through a programmable amplifier circuit. The FPGA module is connected with the programmable amplifier circuit, the main sampling ADC module, an SCI interface and a network interface. A computer is connected with the SCI interface and the network interface. According to the ground magnetic resonance signal detecting device, magnification magnitude of the programmable amplifier circuit is adjusted in real time through a pre-sampling AD, thereby effectively inhibiting amplifier saturation. Furthermore the input value of the main sampling AC reaches a full measuring range as possible, thereby improving signal sampling precision. Because a main sampling AD is triggered and controlled by external interruption, accurate synchronization between the pre-sampling AC and main sampling AD is realized, and good matching between each sampling value and magnification magnitude at this time is ensured.

Description

technical field [0001] The invention relates to a weak signal detection device and detection method, in particular to a detection device and detection method for ground magnetic resonance signals with automatic gain adjustment function in a magnetic resonance water detection system. Background technique [0002] The nuclear magnetic resonance groundwater detection technology is a method that can directly and non-destructively detect groundwater in the field of geophysics today. After the groundwater is excited by the alternating magnetic field, a nuclear magnetic resonance signal is generated. The signal is generally at the nanovolt (nV) level and needs to be amplified by thousands or tens of thousands of times before it can be detected; at the same time, the signal is susceptible to electromagnetic noise from the external environment. interference. The existing ground magnetic resonance signal detection device only manually adjusts the gain once according to the environmen...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R33/44G01V3/14
CPCG01R33/44G01V3/14
Inventor 林婷婷张洋舒旭孙勇万玲赵静
Owner JILIN UNIV
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