CN112526420A - Nuclear magnetic resonance signal receiver and nuclear magnetic resonance equipment - Google Patents
Nuclear magnetic resonance signal receiver and nuclear magnetic resonance equipment Download PDFInfo
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- CN112526420A CN112526420A CN202011415332.8A CN202011415332A CN112526420A CN 112526420 A CN112526420 A CN 112526420A CN 202011415332 A CN202011415332 A CN 202011415332A CN 112526420 A CN112526420 A CN 112526420A
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- 238000005481 NMR spectroscopy Methods 0.000 title claims abstract description 25
- 230000003321 amplification Effects 0.000 claims abstract description 23
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 23
- 230000001172 regenerating effect Effects 0.000 claims abstract description 10
- 239000003990 capacitor Substances 0.000 claims description 44
- 230000010355 oscillation Effects 0.000 claims description 22
- 230000008929 regeneration Effects 0.000 claims description 10
- 238000011069 regeneration method Methods 0.000 claims description 10
- 238000012545 processing Methods 0.000 claims description 6
- 230000008030 elimination Effects 0.000 claims description 4
- 238000003379 elimination reaction Methods 0.000 claims description 4
- 238000012805 post-processing Methods 0.000 claims description 3
- 238000001514 detection method Methods 0.000 abstract description 3
- 238000000926 separation method Methods 0.000 abstract 1
- 230000005669 field effect Effects 0.000 description 21
- 230000035945 sensitivity Effects 0.000 description 3
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000003759 clinical diagnosis Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
- G01R33/3621—NMR receivers or demodulators, e.g. preamplifiers, means for frequency modulation of the MR signal using a digital down converter, means for analog to digital conversion [ADC] or for filtering or processing of the MR signal such as bandpass filtering, resampling, decimation or interpolation
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Abstract
The invention relates to a nuclear magnetic resonance signal receiver and nuclear magnetic resonance equipment, which adopts a regenerative receiving circuit to perform regenerative receiving and detection on signals induced by a receiving coil in the receiver, suppresses the interference caused by out-of-band noise signals, then enters a frequency deviation identification circuit, compares the frequency deviation identification circuit with the pulse width of upper and lower limit cut-off frequencies, adjusts the working frequency of a transmitter when the pulse width is higher than or lower than the upper and lower limit cut-off frequencies, suppresses the interference caused by in-band noise signals, works in a frequency band range, adopts a noise cancellation circuit to perform separation and active noise cancellation on interference pulses with negative polarity, adopts the amplitude of a feedback noise signal, limits the amplitude of a large-amplitude signal with positive polarity, reduces the influence of nonlinearity and noise, improves the precision of the signals, finally enters a gain amplification circuit, changes the conduction degree of a photoelectric coupler OP1, changes the size of a feedback resistor of an amplifier for controllable amplification, the dynamic range of signal amplification is improved.
Description
Technical Field
The invention relates to the technical field of signal processing, in particular to a nuclear magnetic resonance signal receiver and nuclear magnetic resonance equipment.
Background
The nuclear magnetic resonance technology has become a very useful means in scientific research and medical clinical diagnosis, and it is very critical to obtain high-quality images and spectrograms, and to improve the dynamic range of nuclear magnetic resonance signals received by a receiver, the dynamic range of the receiver refers to the ratio of the peak intensity of received signals to the total noise of the receiver, and usually, amplification is adopted to improve the intensity of the amplitude of received small signals (nuclear magnetic resonance signals with smaller amplitudes), but when gain amplification is performed, intermodulation and intermodulation components generated by the receiver per se can be amplified, and noise signals with disordered modes such as power coupling and spatial coupling can also be amplified, so that the dynamic range of actual signals is improved to a very limited extent.
Disclosure of Invention
In view of the above situation, an object of the present invention is to provide a nuclear magnetic resonance signal receiver and a nuclear magnetic resonance device, which effectively solve the problem of limited dynamic range improvement of signals.
The technical scheme for solving the problem is that the device comprises a regeneration receiving circuit, a frequency deviation identification circuit, an intermodulation compensation circuit and a gain amplification circuit, and is characterized in that the regeneration receiving circuit adopts a high-impedance and low-noise following circuit to access a signal induced by a receiving coil in a receiver and then enters an oscillator taking a triode Q2 as a core, and the oscillation frequency of the oscillator is consistent with the frequency of a signal transmitted by a transmitter, so that regeneration receiving is realized;
the frequency deviation identification circuit compares the pulse width of the oscillation frequency of the oscillator with the pulse width of the upper and lower limit cut-off frequency, when the frequency band is within the range, the AND gate U1 outputs high level, the thyristor VTL1 is conducted, the intermodulation compensation circuit works, otherwise, the triode Q6 is conducted, and an interrupt signal is output to the transmitter scanning control unit;
the intermodulation compensation circuit adopts a noise elimination circuit taking an operational amplifier AR2 as a core, and adopts the amplitude of a feedback noise signal to separate interference pulses with negative polarity, so that the amplitude of a large-amplitude signal with positive polarity is limited, and the nonlinearity and the noise influence are reduced;
the gain amplification circuit receives the output signal of the intermodulation compensation circuit, and the output signal enters a post-stage processing circuit after being subjected to controllable gain amplification through an amplifier taking an operational amplifier AR3 as a core.
The invention has the beneficial effects that: the frequency deviation identification circuit compares the pulse width of the frequency of the output signal of the regenerative receiving circuit with the pulse width of upper and lower cut-off frequencies, when the pulse width is higher or lower than the pulse width of the upper and lower cut-off frequencies, the transmitter scanning control unit adjusts the working frequency of the transmitter and inhibits the interference caused by in-band noise signals, when in a frequency band range, the intermodulation compensation circuit works, the noise elimination circuit is adopted to separate the interference pulse of negative polarity by adopting the amplitude of the feedback noise signal, the amplitude of the large amplitude signal of positive polarity is limited, the nonlinearity and the noise influence are reduced, the intermodulation and intermodulation components which can amplify the self generated by the receiver are compensated, and the amplitude of the noise signal is actively counteracted, the accuracy of the signal is improved, the signal enters a gain amplification circuit finally, the amplitude of the output signal of the intermodulation compensation circuit changes the conduction degree of the photoelectric coupler OP1, the negative voltage applied to the grid electrode of the field-effect tube Q5 is changed, the feedback resistance of the amplifier is changed, the amplitude of the amplified signal of the gain amplification circuit is further changed, and the problems that when the gain amplification is directly carried out, the intermodulation and intermodulation components generated by a receiver can be amplified, noise signals can also be amplified, and the dynamic range of actual signals is improved to be limited are solved.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention.
Detailed Description
The foregoing and other technical and scientific aspects, features and utilities of the present invention will be apparent from the following detailed description of the embodiments, which is to be read in connection with the accompanying drawings of fig. 1. The structural contents mentioned in the following embodiments are all referred to the attached drawings of the specification.
Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.
The first embodiment of the invention relates to a nuclear magnetic resonance signal receiver and nuclear magnetic resonance equipment, which comprises a regeneration receiving circuit, a frequency deviation identification circuit, an intermodulation compensation circuit and a gain amplification circuit, wherein the regeneration receiving circuit adopts a high-impedance and low-noise follower circuit to access a signal induced by a receiving coil in the receiver, then the signal enters an oscillator controlled by intermittent oscillation, the oscillation frequency of the oscillator is consistent with the frequency of a signal transmitted by a transmitter, the regeneration receiving detection of the signal is realized, the frequency-selecting bandwidth range of the intermittent oscillation is the frequency-selecting bandwidth range which improves the anti-interference capability under the premise of ensuring the sensitivity and inhibits the interference caused by an out-of-band noise signal, the frequency deviation identification circuit compares the pulse width of the oscillation frequency of the oscillator with the pulse width of upper and lower limit cut-off frequencies, the pulse width of the specific oscillation frequency of the oscillator is unidirectionally conducted by a diode D1 and is respectively added to the inverting input end, the, The non-inverting input terminal of the operational amplifier AR4, the non-inverting input terminal of the operational amplifier AR1, and the inverting input terminal of the operational amplifier AR4 are connected to the voltage provided by the voltage divider circuit of the resistor R18, the resistor R19, and the resistor R20, that is, the voltage corresponding to the pulse width of the upper limit cut-off frequency and the pulse width of the lower limit cut-off frequency, when the frequency deviation is within the frequency band range, that is, when the frequency deviation is within the allowable range, the and gate U1 outputs a high level, the thyristor VTL1 is turned on, the intermodulation compensation circuit operates, otherwise, the transistor Q6 is turned on, and outputs an interrupt signal to the transmitter scan control unit, the transmitter scan control unit adjusts the operating frequency of the transmitter to suppress the interference caused by the in-band noise signal, when the thyristor VTL1 is turned on, the regenerative receiving circuit enters the noise cancellation circuit with the operational amplifier AR2 as the core, and performs active, the amplitude of the signal output by the intermodulation compensation circuit is controlled and amplified by an amplifier consisting of an operational amplifier AR3, a resistor R14, a resistor R16, a field effect tube Q5, a photoelectric coupler OP1, an electrolytic capacitor E1 and an inductor L3, and then enters a post-stage processing circuit, the amplitude of the signal output by the intermodulation compensation circuit changes the conduction degree of the photoelectric coupler OP1 (particularly a linear photoelectric coupler), changes the negative voltage applied to the grid electrode of a field effect tube Q5, changes the size of a feedback resistor consisting of a resistor R15 and a field effect tube Q5 which are connected in series, further changes the amplitude of the signal amplified by the gain amplification circuit, and solves the problem that when the gain amplification is directly carried out, intermodulation and intermodulation products generated by the receiver can be amplified, and a noise signal can also be amplified, so that the problem that the dynamic range of an actual signal is improved to a very limited extent is caused.
In the second embodiment, on the basis of the first embodiment, the regenerative receiving circuit adopts a high-impedance and low-noise following circuit composed of capacitors C1 and C2, a resistor R1-a resistor R3, and a field-effect transistor Q1 to access a signal induced by a receiving coil in a receiver, and then the signal enters an oscillator controlled by intermittent oscillation and composed of a triode Q2, inductors L1 and L2, a resistor R4-a resistor R6, a capacitor C5-a capacitor C7, and a varactor DC1, the oscillation frequency of the oscillator is consistent with the frequency of a signal transmitted by a transmitter, so as to realize regenerative receiving and detecting of the signal, the frequency-selecting bandwidth range of the intermittent oscillation is to improve the anti-interference capability and suppress the interference caused by an out-of-band noise signal on the premise of ensuring the sensitivity, for example, H atomic resonance (abundant in human body) is clinically used at present, the resonance frequency is 42.58MHz/T, and the frequency-selecting bandwidth range of the intermittent oscillation is plus, the transmitter scanning control unit outputs a control signal to be added to a negative electrode of a varactor DC1 for keeping the oscillation frequency of an oscillator consistent with the frequency of a signal transmitted by a transmitter, and comprises a capacitor C1, one end of the capacitor C1 is connected with a signal induced by a receiving coil, the other end of the capacitor C1 is respectively connected with one end of a grounding resistor R1 and a grid electrode of a field effect tube Q1, a source electrode of the field effect tube Q1 is connected with the ground through a resistor R2, a drain electrode of the field effect tube Q1 is respectively connected with one end of a resistor R3 and one end of a capacitor C2, the other end of the resistor R3 is connected with +5V, the other end of the capacitor C2 is respectively connected with a collector electrode of a triode Q2, one end of an inductor L1 and one end of a capacitor C4, the other end of the inductor L1 is respectively connected with one end of a standby resistor R4 and one end of a grounding capacitor C5, a base electrode of a triode Q573, One end of a resistor R6 and one end of a capacitor C7, the other end of a resistor R6 is respectively connected with the other end of the capacitor C7, one end of a grounded capacitor C9 and one end of an inductor L2, the other end of a resistor R6 regenerates and receives a circuit output signal, the other end of the inductor L2 is respectively connected with an emitter of a triode Q2, the other end of a capacitor C4 and one end of the capacitor C8, the other end of the capacitor C8 is connected with a cathode of a varactor DC1, and an anode of the varactor DC1 is connected with the ground.
In the third embodiment, on the basis of the first embodiment, the frequency deviation identification circuit compares the pulse width of the oscillator oscillation frequency with the pulse widths of the upper and lower cutoff frequencies, after the pulse width of the oscillator oscillation frequency is unidirectionally conducted through the diode D1, the pulse width of the oscillator oscillation frequency is charged through the resistor R17 and the capacitor C10 and is respectively added to the inverting input terminal of the operational amplifier AR1 and the non-inverting input terminal of the operational amplifier AR4, the non-inverting input terminal of the operational amplifier AR1 and the inverting input terminal of the operational amplifier AR4 are connected to the voltage provided by the voltage divider circuit of the resistor R18, the resistor R19 and the resistor R20, that is, the voltage corresponding to the pulse width of the upper cutoff frequency and the pulse width of the lower cutoff frequency, when the frequency band is within the allowable range, that is, for example, clinically H-atom resonance (high abundance in human body) is currently used, when the resonance frequency is plus or minus 1.5MHz of 42.58MHz, the thyristor VTL1 is turned on, the intermodulation compensation circuit works, otherwise, the triode Q6 is turned on, an interrupt signal is output to the transmitter scanning control unit, the transmitter scanning control unit adjusts the working frequency of the transmitter, and the interference caused by the in-band noise signal is inhibited, the triode Q6 comprises a diode D1, the cathode of the diode D1 is connected with the other end of a resistor R6, the anode of a diode D1 is respectively connected with one end of a grounding capacitor C10, one end of a resistor R17, the inverting input end of an operational amplifier AR1 and the non-inverting input end of an operational amplifier AR4, the non-inverting input end of the operational amplifier AR1 is respectively connected with one end of a resistor R18 and one end of a resistor R19, the inverting input end of an operational amplifier AR4 is respectively connected with the other end of a resistor R19 and one end of a grounding resistor R20, the other end of a resistor R17 and the other end of a resistor R18 are connected with, the output end of the operational amplifier AR4 is connected with a pin B of an AND gate U1, a pin Y of the AND gate U1 is respectively connected with a control electrode of a thyristor VTL1, one end of a resistor R21 and one end of a capacitor C11, the other end of the resistor R21 is respectively connected with a base electrode of a triode Q6 at the other end of the capacitor C11, an emitter of the triode Q6 is connected with +5V of a power supply, and a collector of the triode Q6 and one end of a grounding resistor R22 are connected with the transmitter scanning control unit.
Fourth embodiment, based on the first embodiment, when the thyristor VTL1 is turned on, the regenerative receiving circuit enters the noise canceling circuit with the operational amplifier AR2 as the core, and separates the negative interference pulse by feeding back the amplitude of the noise signal, and the positive large amplitude signal is clipped to reduce the influence of nonlinearity and noise, the detailed principle is that the operational amplifier AR2 and the resistor R8-the resistor R11 constitute the differential amplifier for first-stage amplification and then output, when the amplified signal contains the negative interference pulse, the transistor Q4 is turned on to trigger the transistor Q3 to be turned on, the amplitude of the noise signal is fed back to the inverting input terminal of the operational amplifier AR2 through the transistor Q3 to be separated, so as to realize active noise reduction, when the positive large amplitude signal is generated, the field effect transistor T1 is turned on, the differential amplifier is clipped and amplified to output, and reduce the influence of nonlinearity and noise, the receiver compensates intermodulation and intermodulation products generated by the receiver and actively cancels noise signal amplitude, comprises a thyristor VTL1, the anode of the thyristor VTL1 is connected with the other end of a resistor R6, the cathode of the thyristor VTL1 is connected with one end of a resistor R8, the other end of the resistor R8 is respectively connected with one end of a resistor R11, the non-inverting input end of an operational amplifier AR2 and the source of a field-effect tube T1, the output end of the operational amplifier AR2 is respectively connected with the other end of a resistor R11, one end of a resistor R12 and the drain of the field-effect tube T1, the other end of a resistor R12 is respectively connected with the collector of a triode Q4 and the lower end of a potentiometer RW1, the adjustable end of the potentiometer RW1 is connected with the gate of a field-effect tube T1, the upper end of the potentiometer RW1 is connected with a power supply +9V, the base of a triode Q4 is connected with a power supply-5V through a resistor R23, the emitter of a triode Q4 is connected with the base of, the collector of the transistor Q3 is connected to one end of a ground resistor R10 and the inverting input terminal of the operational amplifier AR2 through a resistor R9.
Fifth embodiment, on the basis of the first embodiment, the gain amplifying circuit receives the output signal of the intermodulation compensation circuit, and the output signal is controllably gain-amplified by an amplifier composed of an operational amplifier AR3, a resistor R14-a resistor R16, a field-effect transistor Q5, a photocoupler OP1, an electrolytic capacitor E1, and an inductor L3, and then enters a post-processing circuit, wherein the detailed principle is that the amplitude of the output signal of the intermodulation compensation circuit changes the conduction degree of the photocoupler OP1 (specifically, a linear photocoupler), changes the negative voltage applied to the gate of the field-effect transistor Q5, changes the magnitude of a feedback resistor composed of a resistor R15 and a field-effect transistor Q5 connected in series, and further changes the amplitude of the signal amplified by the gain amplifying circuit, and then enters the post-processing circuit to solve the problem that when the gain amplification is directly performed, the intermodulation and intermodulation components generated by the receiver itself and the noise signal are amplified, the problem that the dynamic range of the actual signal is improved to a very limited extent is caused, which includes an inductor L3 and a resistor R14, one end of the inductor L3 and one end of the resistor R14 are connected with the other end of the resistor R12, the other end of the resistor R14 is respectively connected with one end of the resistor R15, the non-inverting input end of the operational amplifier AR3, the other end of the resistor R15 is connected with the source electrode of the field effect transistor Q5, the drain electrode of the field effect transistor Q5 and the output end of the operational amplifier AR3 are connected to the post-stage processing circuit, the inverting input end of the operational amplifier AR3 is connected to the ground, the other end of the inductor L3 is connected with the pin 2 of the photoelectric coupler OP1, the pin 1 of the photoelectric coupler OP1 is connected with the power supply +5V, the pin 4 of the photoelectric coupler OP1 is connected with the power supply-2.5V, the pin 3 of the photoelectric coupler OP1 is connected with one end of the resistor R16, the other end of the resistor R16 is respectively connected with the grid electrode of the field effect transistor Q5 and the anode electrode of the electrolytic capacitor E85.
When the invention is used, a regenerative receiving circuit adopts a high-impedance and low-noise following circuit to access a signal induced by a receiving coil in a receiver, and then the signal enters an oscillator controlled by intermittent oscillation, the oscillation frequency of the oscillator is consistent with the frequency of a signal transmitted by a transmitter, so that the regenerative receiving and detection of the signal are realized, the frequency-selecting bandwidth range of the intermittent oscillation is to improve the anti-interference capability and inhibit the interference caused by out-of-band noise signals on the premise of ensuring the sensitivity, a frequency deviation identification circuit compares the pulse width of the oscillation frequency of the oscillator with the pulse widths of upper and lower limit cut-off frequencies, the pulse width of the oscillation frequency of the oscillator is charged by a resistor R17 and a capacitor C10 and is respectively added to the inverting input end of an operational amplifier AR1 and the non-inverting input end of an operational amplifier AR4, the non-inverting input end of the operational amplifier AR1 and the inverting input end of the operational amplifier AR4, The voltage provided by the resistor R19 and the resistor R20 voltage dividing circuit, namely the voltage corresponding to the pulse width of the upper limit cut-off frequency and the pulse width of the lower limit cut-off frequency, when the frequency band is within the frequency band range, namely the frequency deviation is within the allowable range, the interrupt signal is output to the transmitter scanning control unit, the transmitter scanning control unit adjusts the working frequency of the transmitter, and inhibits the interference caused by the in-band noise signal, when the cross modulation compensation circuit is switched on in the thyristor VTL1, the regeneration receiving circuit enters the noise elimination circuit taking the operational amplifier AR2 as the core, the interference pulse of the negative polarity is separated by adopting the amplitude of the feedback noise signal, the amplitude limit of the large amplitude signal of the positive polarity is reduced, the nonlinear and noise influence are reduced, the cross modulation and the cross modulation component which can amplify the self generation of the receiver are compensated, and the amplitude of the noise signal is actively cancelled, the precision of the signal, the amplifier composed of an operational amplifier AR3, a resistor R14-a resistor R16, a field effect tube Q5, a photoelectric coupler OP1, an electrolytic capacitor E1 and an inductor L3 is subjected to controllable gain amplification and then enters a post-stage processing circuit, and the detailed principle is that the amplitude of an output signal of an intermodulation compensation circuit changes the conduction degree of the photoelectric coupler OP1 (specifically a linear photoelectric coupler), changes the magnitude of a negative voltage applied to the grid electrode of the field effect tube Q5, changes the magnitude of a feedback resistor composed of the resistor R15 and the field effect tube Q5 which are connected in series, further changes the amplitude of an amplification signal of a gain amplification circuit, and solves the problems that when gain amplification is directly performed, intermodulation and intermodulation components generated by a receiver are amplified, noise signals are also amplified, and the dynamic range of actual signals is improved to be limited.
Claims (5)
1. A nuclear magnetic resonance signal receiver and nuclear magnetic resonance equipment comprises a regeneration receiving circuit, a frequency deviation identification circuit, an intermodulation compensation circuit and a gain amplification circuit, and is characterized in that the regeneration receiving circuit adopts a high-impedance and low-noise following circuit to access a signal induced by a receiving coil in the receiver, and then the signal enters an oscillator with a triode Q2 as a core, and the oscillation frequency of the oscillator is consistent with the frequency of a signal transmitted by a transmitter, so that regeneration receiving is realized;
the frequency deviation identification circuit compares the pulse width of the oscillation frequency of the oscillator with the pulse width of the upper and lower limit cut-off frequency, when the frequency band is within the range, the AND gate U1 outputs high level, the thyristor VTL1 is conducted, the intermodulation compensation circuit works, otherwise, the triode Q6 is conducted, and an interrupt signal is output to the transmitter scanning control unit;
the intermodulation compensation circuit adopts a noise elimination circuit taking an operational amplifier AR2 as a core, and adopts the amplitude of a feedback noise signal to separate interference pulses with negative polarity, so that the amplitude of a large-amplitude signal with positive polarity is limited, and the nonlinearity and the noise influence are reduced;
the gain amplification circuit receives the output signal of the intermodulation compensation circuit, and the output signal enters a post-stage processing circuit after being subjected to controllable gain amplification through an amplifier taking an operational amplifier AR3 as a core.
2. The nuclear magnetic resonance signal receiver and nuclear magnetic resonance apparatus as claimed in claim 1, wherein the regenerative receiving circuit includes a capacitor C1, one end of the capacitor C1 is connected to a signal induced by the receiving coil, the other end of the capacitor C1 is connected to one end of a ground resistor R1 and a gate of a fet Q1, a source of the fet Q1 is connected to ground through a resistor R2, a drain of the fet Q1 is connected to one end of the resistor R3 and one end of the capacitor C2, the other end of the resistor R3 is connected to +5V, the other end of the capacitor C2 is connected to a collector of a transistor Q2, one end of an inductor L1 and one end of a capacitor C4, the other end of the inductor L1 is connected to one end of a standby resistor R4 and one end of a ground capacitor C5, a base of the transistor Q2 is connected to one end of a ground resistor R5, one end of a ground capacitor C6, one end of a resistor R6 and one end of a capacitor C7, the other end of the resistor R6 is connected with the other end of the capacitor C7, one end of the grounded capacitor C9 and one end of the inductor L2 respectively, the other end of the resistor R6 regenerates and receives a circuit output signal, the other end of the inductor L2 is connected with the emitter of the triode Q2, the other end of the capacitor C4 and one end of the capacitor C8 respectively, the other end of the capacitor C8 is connected with the cathode of the varactor DC1, and the anode of the varactor DC1 is connected with the ground.
3. The nuclear magnetic resonance signal receiver and nuclear magnetic resonance device as claimed in claim 1, wherein the frequency deviation identification circuit includes a diode D1, a cathode of the diode D1 is connected to the other end of the resistor R6, an anode of the diode D1 is connected to one end of the ground capacitor C10, one end of the resistor R17, an inverting input of the operational amplifier AR1, and a non-inverting input of the operational amplifier AR4, a non-inverting input of the operational amplifier AR1 is connected to one end of the resistor R18 and one end of the resistor R19, an inverting input of the operational amplifier AR4 is connected to the other end of the resistor R19 and one end of the ground resistor R20, the other end of the resistor R17 and the other end of the resistor R18 are connected to +5V, an output of the operational amplifier AR1 is connected to the pin a of the and gate U1, an output of the operational amplifier AR4 is connected to the pin B of the and gate U1, and gate U1 is connected to the control electrode Y, One end of a resistor R21, one end of a capacitor C11, the other end of a resistor R21 are respectively connected with the base electrode of a triode Q6 at the other end of the capacitor C11, the emitting electrode of the triode Q6 is connected with +5V of a power supply, and the collecting electrode of the triode Q6 and one end of a grounding resistor R22 are connected with the transmitter scanning control unit.
4. The nuclear magnetic resonance signal receiver and nuclear magnetic resonance device as claimed in claim 1, wherein the intermodulation compensation circuit includes a thyristor VTL1, the anode of the thyristor VTL1 is connected to the other end of the resistor R6, the cathode of the thyristor VTL1 is connected to one end of the resistor R8, the other end of the resistor R8 is connected to one end of the resistor R11, the non-inverting input terminal of the operational amplifier AR2 and the source of the fet T1, the output terminal of the operational amplifier AR2 is connected to the other end of the resistor R11, one end of the resistor R12 and the drain of the fet T1, the other end of the resistor R12 is connected to the collector of the transistor Q4 and the lower end of the potentiometer RW 48, the adjustable end of the potentiometer RW1 is connected to the gate of the fet T1, the upper end of the potentiometer RW1 is connected to the power supply +9V, the base of the transistor Q4 is connected to the power supply-5V through the resistor R23, and the emitter of the transistor Q4 is, the emitter of the transistor Q3 is connected to the detected noise signal amplitude through a resistor R7, and the collector of the transistor Q3 is connected to one end of a ground resistor R10 and the inverting input terminal of the operational amplifier AR2 through a resistor R9.
5. The nuclear magnetic resonance signal receiver and nuclear magnetic resonance device as claimed in claim 1, wherein the gain amplifying circuit includes an inductor L3 and a resistor R14, one end of the inductor L3 and one end of the resistor R14 are connected to the other end of the resistor R12, the other end of the resistor R14 is connected to one end of the resistor R15 and the non-inverting input end of the operational amplifier AR3, the other end of the resistor R15 is connected to the source of the fet Q5, the drain of the fet Q5 and the output end of the operational amplifier AR3 are connected to the post-processing circuit, the inverting input end of the operational amplifier AR3 is connected to ground, the other end of the inductor L3 is connected to the pin 2 of the photocoupler OP1, the pin 1 of the photocoupler OP1 is connected to the power supply +5V, the pin 4 of the photocoupler 36op 1 is connected to the power supply-2.5V, the pin 3 of the photocoupler OP1 is connected to one end of the resistor R42, the other end of the resistor R3946, The positive electrode of the electrolytic capacitor E1 and the negative electrode of the electrolytic capacitor E1 are connected to ground.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113467320A (en) * | 2021-07-21 | 2021-10-01 | 西安龙飞电气技术有限公司 | Weak signal detection algorithm based on gain compensation |
| CN113921239A (en) * | 2021-11-02 | 2022-01-11 | 深圳市联影高端医疗装备创新研究院 | Coil system |
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2020
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113467320A (en) * | 2021-07-21 | 2021-10-01 | 西安龙飞电气技术有限公司 | Weak signal detection algorithm based on gain compensation |
| CN113921239A (en) * | 2021-11-02 | 2022-01-11 | 深圳市联影高端医疗装备创新研究院 | Coil system |
| CN113921239B (en) * | 2021-11-02 | 2024-06-04 | 深圳市联影高端医疗装备创新研究院 | Coil system |
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Application publication date: 20210319 |