Low-power-consumption and high-precision magnetic resonance signal phase closed-loop control method and system

Abstract

The invention provides a low-power-consumption and high-precision magnetic resonance signal phase closed-loop control method and system, and the method comprises the steps: firstly generating a magnetic field excitation signal through a DDS chip, exciting alkali metal atoms in an atomic gas chamber, and generating two orthogonal reference signals for extracting the phase information of a magnetic resonance signal; sending the magnetic resonance signal and a reference signal into an analog multiplier at the same time, performing low-pass filtering, and extracting phase information of the magnetic resonance signal; phase lag and drift in the system are suppressed through phase compensation; and finally, through PID control, the output frequency of the DDS chip is changed, and closed-loop control of the phase is realized. According to the technical scheme, the technical problems that in the prior art, the overall power consumption of a system is large, and the low-power-consumption engineering environment application requirement of the atom magnetometer is difficult to meet are solved.

Description

Technical Field

[0001] The present invention relates to the field of quantum sensing technology, and in particular to a low-power, high-precision magnetic resonance signal phase closed-loop control method and system. Background Art

[0002] Alkali metal atomic magnetometers use the precession of electron spins or nuclear spins in a magnetic field to measure magnetic fields. They have the advantages of high precision and small size. They are mainly used for measuring the earth's magnetic field, weak biological magnetic measurements such as brain magnetism and core magnetism, and underwater, surface and aerial target detection. They are of great significance in the fields of national economic construction and national defense.

[0003] When the atoms in the atomic gas chamber work in a resonant state, the phase difference between the magnetic resonance signal and the reference excitation signal is a constant, and the atomic magnetometer has the highest sensitivity and stability. Therefore, in order to ensure the magnetic field measurement accuracy of the atomic magnetometer and improve the magnetic field control performance, it is first necessary to achieve high-precision phase closed-loop control of the magnetic resonance signal. In addition, in view of the urgent need for small unmanned platforms such as anchor magnetic fuses, magnetic buoys, and underwater submersibles to have increasing self-sustaining requirements such as long flight time, atomic magnetometers face the challenge of achieving high precision with low power consumption.

[0004] The traditional magnetic resonance phase closed-loop control method (such as CN114460506 B, magnetic resonance signal phase closed-loop control method and system based on variable parameter control) is achieved through digital demodulation methods of high-power devices such as high-speed ADC, high-speed DAC and FPGA. The overall power consumption of the system is large, which is difficult to meet the low-power engineering environment application requirements of atomic magnetometers. Summary of the invention

[0005] The present invention provides a low-power, high-precision magnetic resonance signal phase closed-loop control method and system, which can solve the technical problem in the prior art that the overall power consumption of the system is large and it is difficult to meet the application requirements of the low-power engineering environment of the atomic magnetometer.

[0006] According to one aspect of the present invention, a low-power, high-precision magnetic resonance signal phase closed-loop control method is provided, and the low-power, high-precision magnetic resonance signal phase closed-loop control method comprises: generating a magnetic field excitation signal and two reference signals with a phase difference of 90° by a DDS chip; multiplying the magnetic resonance signal with the two reference signals by an analog multiplier to obtain an output result of the analog multiplier, and performing low-pass filtering on the output result to obtain two-way filtered output results; collecting the two-way filtered output results by a low-power ADC chip, dividing and simplifying the two-way filtered output results to obtain a phase difference between the magnetic resonance signal and the reference signal; and obtaining a phase difference between the magnetic resonance signal and the reference signal according to the phase difference between the magnetic resonance signal and the reference signal. The phase difference between the magnetic resonance signal and the magnetic field excitation signal is calculated by the phase difference of the reference signal; the phase difference between the magnetic resonance signal and the magnetic field excitation signal is phase compensated; the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal is compared with the expected phase difference, and the difference between the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal and the expected phase difference is substituted into the PID closed-loop control algorithm to obtain the change in the frequency of the excitation signal, and the output frequency of the DDS chip is changed until the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal is equal to the expected phase difference, thereby completing the phase closed-loop control of the magnetic resonance signal.

[0007] Furthermore, the magnetic field excitation signal x A The expression is x A =Asin(ωt+θ A ), reference signal x B ,x C The expression is Where A is the amplitude of the magnetic field excitation signal, ω is the signal frequency, t is the time, θ A is the phase of the magnetic field excitation signal, B is the signal amplitude, θ B ,θ C is the phase of the two reference signals, and the phase difference is 90°.

[0008] Furthermore, the magnetic resonance signal expression of the atoms in the atomic gas chamber after resonance is x D =Dsin(ωt+θ D ), where D is the magnetic resonance signal amplitude, ω is the signal frequency, t is the time, θ D is the magnetic resonance signal phase.

[0009] Furthermore, the output of the analog multiplier is Y B , Y C It is the output result of the analog multiplier, which is the superposition of the DC component and the high-frequency AC component.

[0010] Furthermore, the two-way filtering output result Y′ B , Y′ CThe expression is

[0011] Furthermore, the phase difference between the magnetic resonance signal and the reference signal is θ D -θ B =acot(Y).

[0012] Furthermore, the phase difference between the magnetic resonance signal and the magnetic field excitation signal is Among them, θ A-B It is the phase difference between the reference signal and the simulated excitation signal, which can be measured and solved and is a constant.

[0013] Furthermore, the phase difference between the magnetic resonance signal after phase compensation and the magnetic field excitation signal is θ=Φ(θ D-A ,T).

[0014] According to another aspect of the present invention, a low-power, high-precision magnetic resonance signal phase closed-loop control system is provided. The low-power, high-precision magnetic resonance signal phase closed-loop control system uses the low-power, high-precision magnetic resonance signal phase closed-loop control method as described above to perform magnetic resonance signal phase closed-loop control.

[0015] Furthermore, a low-power, high-precision magnetic resonance signal phase closed-loop control system includes a DDS chip, an atomic gas chamber, an analog multiplier, a low-pass filter, a low-power ADC chip and a low-power ARM processor. The DDS chip is used to generate a magnetic field excitation signal and two reference signals with a phase difference of 90°. The analog multiplier is used to multiply the magnetic resonance signal output by the atomic gas chamber with the two reference signals to obtain an output result of the analog multiplier. The low-pass filter is used to perform low-pass filtering on the output result to obtain two-way filtered output results. The low-power ADC chip is used to collect the two-way filtered output results; the low-power ARM processor is used to divide and simplify the two-way filtered output results to obtain the magnetic resonance signal and the reference signal. The phase difference of the reference signal is measured, and the phase difference between the magnetic resonance signal and the magnetic field excitation signal is calculated according to the phase difference between the magnetic resonance signal and the reference signal. The phase difference between the magnetic resonance signal and the magnetic field excitation signal is phase compensated, and the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal is compared with the expected phase difference. The difference between the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal and the expected phase difference is substituted into the PID closed-loop control algorithm to obtain the change in the frequency of the excitation signal, and the output frequency of the DDS chip is changed until the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal is equal to the expected phase difference, thereby completing the phase closed-loop control of the magnetic resonance signal.

[0016] By applying the technical solution of the present invention, a low-power, high-precision magnetic resonance signal phase closed-loop control method is provided. In this method, a low-power DDS chip generates a magnetic field excitation signal to excite alkali metal atoms in an atomic gas chamber, and generates two orthogonal reference signals for extracting the phase information of the magnetic resonance signal; then the magnetic resonance signal and the reference signal are simultaneously sent to an analog multiplier, and low-pass filtered to extract the phase information of the magnetic resonance signal; then, phase compensation is used to suppress phase lag and drift in the system; finally, PID control is used to change the output frequency of the DDS chip to achieve closed-loop control of the phase. Therefore, compared with the prior art, the low-power, high-precision magnetic resonance signal phase closed-loop control method provided by the present invention is based on analog multipliers, low-power DDS chips, ADC chips and ARM processors, etc., to build and design the hardware and software of the magnetic resonance signal closed-loop control. On the basis of ensuring the high precision of phase control, the system power consumption is greatly reduced, and temperature compensation is performed to suppress the temperature drift of analog demodulation, thereby improving the environmental adaptability of the system, meeting the requirements of low-power engineering applications, realizing the magnetic resonance signal phase closed-loop control, greatly reducing the system power consumption, and suppressing the phase temperature drift, improving the magnetic field measurement stability, and ensuring the environmental adaptability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A schematic structural diagram of a low-power, high-precision magnetic resonance signal phase closed-loop control system provided according to a specific embodiment of the present invention is shown. DETAILED DESCRIPTION

[0019] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0021] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0022] like Figure 1 As shown, according to a specific embodiment of the present invention, a low-power, high-precision magnetic resonance signal phase closed-loop control method is provided, and the low-power, high-precision magnetic resonance signal phase closed-loop control method comprises: generating a magnetic field excitation signal and two reference signals with a phase difference of 90° by a DDS chip; multiplying the magnetic resonance signal with the two reference signals by an analog multiplier to obtain an output result of the analog multiplier, and performing low-pass filtering on the output result to obtain two-way filtered output results; collecting the two-way filtered output results by a low-power ADC chip, dividing and simplifying the two-way filtered output results to obtain the phase difference between the magnetic resonance signal and the reference signal; and obtaining the phase difference between the magnetic resonance signal and the reference signal according to the magnetic resonance signal. The phase difference between the magnetic resonance signal and the magnetic field excitation signal is calculated by using the phase difference between the phase compensation signal and the reference signal; the phase difference between the magnetic resonance signal and the magnetic field excitation signal is phase compensated; the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal is compared with the expected phase difference, and the difference between the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal and the expected phase difference is substituted into the PID closed-loop control algorithm to obtain the change in the frequency of the excitation signal, and the output frequency of the DDS chip is changed until the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal is equal to the expected phase difference, thereby completing the phase closed-loop control of the magnetic resonance signal.

[0023] By applying this configuration, a low-power, high-precision magnetic resonance signal phase closed-loop control method is provided. In this method, a low-power DDS chip generates a magnetic field excitation signal to excite alkali metal atoms in the atomic gas chamber, and generates two orthogonal reference signals for extracting the phase information of the magnetic resonance signal; then the magnetic resonance signal and the reference signal are simultaneously sent to an analog multiplier, and low-pass filtered to extract the phase information of the magnetic resonance signal; then, phase compensation is used to suppress the phase lag and drift in the system; finally, PID control is used to change the output frequency of the DDS chip to achieve closed-loop control of the phase. Therefore, compared with the prior art, the low-power, high-precision magnetic resonance signal phase closed-loop control method provided by the present invention is based on analog multipliers, low-power DDS chips, ADC chips and ARM processors, etc., to build and design the hardware and software of the magnetic resonance signal closed-loop control. On the basis of ensuring the high precision of phase control, the system power consumption is greatly reduced, and temperature compensation is performed to suppress the temperature drift of analog demodulation, thereby improving the environmental adaptability of the system, meeting the requirements of low-power engineering applications, realizing the magnetic resonance signal phase closed-loop control, greatly reducing the system power consumption, and suppressing the phase temperature drift, improving the magnetic field measurement stability, and ensuring the environmental adaptability of the system.

[0024] Specifically, the present invention proposes a low-power, high-precision magnetic resonance signal phase closed-loop control method and device, including the construction of a hardware system and the implementation of a software algorithm.

[0025] First, the DDS chip generates a magnetic field excitation signal to excite the alkali metal atoms in the atomic gas chamber and generate two orthogonal reference signals for extracting the phase information of the magnetic resonance signal. Then, the magnetic resonance signal and the reference signal are simultaneously sent to the analog multiplier and low-pass filtered to extract the phase information of the magnetic resonance signal. Then, phase compensation is used to suppress the phase lag and drift in the system. Finally, PID control is used to change the output frequency of the DDS chip to achieve closed-loop control of the phase.

[0026] The technical solution of the present invention:

[0027] A low-power, high-precision magnetic resonance signal phase closed-loop control method and device, comprising at least analog demodulation and phase compensation.

[0028] (1) Generation of magnetic field excitation signal and reference signal

[0029] The magnetic field excitation signal and the reference signal are generated by the DDS chip. The DDS technology is relatively mature and will not be discussed in this invention. The expression of the excitation signal is as follows:

[0030] x A =Asin(ωt+θ A ) (1)

[0031] Where A is the signal amplitude, ω is the signal frequency, t is the time, θ A For phase.

[0032] The expression of the reference signal is as follows:

[0033]

[0034] Where B is the signal amplitude, ω is the signal frequency, t is the time, θ B ,θ C is the phase, and the phase difference is 90°.

[0035] (2) Phase analog demodulation

[0036] The expression of the magnetic resonance signal after atomic resonance in the atomic gas cell is as follows:

[0037] x D =Dsin(ωt+θ D ) (3)

[0038] Where D is the signal amplitude, ω is the signal frequency, t is the time, θ D For phase.

[0039] By using an analog multiplier, the magnetic resonance signal (Equation (3)) is multiplied by the two reference signals (Equation (2)) to obtain:

[0040]

[0041] Among them, Y B , Y C It is the output result of the analog multiplier, which is the superposition of the DC component and the high-frequency AC component.

[0042] The output of the analog multiplier is low-pass filtered to obtain:

[0043]

[0044] The filtered result Y′ is collected by a low-power ADC chip B , Y′ C , and divide the two:

[0045]

[0046] From formula (2), we can know that θ B ,θ C The phase difference is 90°, so the above formula can be simplified to:

[0047]

[0048] The phase difference between the magnetic resonance signal and the reference signal can be expressed as:

[0049] θ D -θ B =arccot(Y)(8)

[0050] The system needs to solve the phase difference θ between the magnetic resonance signal (3) and the analog excitation signal (1): D-A , and the phase between the reference signal and the simulated excitation signal is different, that is, θ A ≠θ B , but the difference is a constant, so the final phase can be expressed as:

[0051]

[0052] Among them, θ A-B It is the phase difference between the reference signal and the simulated excitation signal, which can be measured and solved and is a constant.

[0053] (3) Phase compensation

[0054] Since there is a constant bias in the output of the analog multiplier, and the bias drifts with the operating temperature, affecting the accuracy of phase solution, compensation is required.

[0055] The phase drift is related to the temperature T:

[0056] θ=Φ(θ D-A ,T) (10)

[0057] Among them, Φ is the relationship function between temperature and phase obtained through experimental calibration.

[0058] (4)PID closed-loop control

[0059] The phase difference in equation (10) is compared with the expected phase difference, and the difference is brought into the PID closed-loop control algorithm to obtain the change in the excitation signal frequency, and the DDS output frequency is changed until the phase difference is equal to the expected phase difference, thereby realizing the phase closed-loop control of the system.

[0060] The beneficial results of this system compared with the existing technology:

[0061] The closed-loop control of the phase of the magnetic resonance signal is realized, which greatly reduces the power consumption of the system, suppresses the phase temperature drift, improves the stability of the magnetic field measurement, and ensures the environmental adaptability of the system.

[0062] According to another aspect of the present invention, a low-power, high-precision magnetic resonance signal phase closed-loop control system is provided. The low-power, high-precision magnetic resonance signal phase closed-loop control system uses the low-power, high-precision magnetic resonance signal phase closed-loop control method as described above to perform magnetic resonance signal phase closed-loop control.

[0063] By applying this configuration, a low-power, high-precision magnetic resonance signal phase closed-loop control system is provided. The system is based on analog multipliers, low-power DDS chips, ADC chips and ARM processors, and the hardware and software of the magnetic resonance signal closed-loop control are constructed and designed. On the basis of ensuring the high precision of phase control, the system power consumption is greatly reduced, and temperature compensation is performed to suppress the temperature drift of analog demodulation, thereby improving the environmental adaptability of the system and meeting the requirements of low-power engineering applications. The magnetic resonance signal phase closed-loop control is realized, the system power consumption is greatly reduced, and the phase temperature drift is suppressed, the magnetic field measurement stability is improved, and the environmental adaptability of the system is ensured.

[0064] Furthermore, in the present invention, a low-power, high-precision magnetic resonance signal phase closed-loop control system includes a DDS chip, an atomic gas chamber, an analog multiplier, a low-pass filter, a low-power ADC chip and a low-power ARM processor. The DDS chip is used to generate a magnetic field excitation signal and two reference signals with a phase difference of 90°. The analog multiplier is used to multiply the magnetic resonance signal output by the atomic gas chamber with the two reference signals to obtain an output result of the analog multiplier. The low-pass filter is used to perform low-pass filtering on the output result to obtain two-way filtered output results. The low-power ADC chip is used to collect the two-way filtered output results; the low-power ARM processor is used to divide and simplify the two-way filtered output results to obtain a magnetic resonance signal. The phase difference between the magnetic resonance signal and the reference signal is calculated, and the phase difference between the magnetic resonance signal and the magnetic field excitation signal is obtained according to the phase difference between the magnetic resonance signal and the reference signal. The phase difference between the magnetic resonance signal and the magnetic field excitation signal is phase compensated, and the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal is compared with the expected phase difference. The difference between the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal and the expected phase difference is substituted into the PID closed-loop control algorithm to obtain the change in the frequency of the excitation signal, and the output frequency of the DDS chip is changed until the phase difference between the phase compensated magnetic resonance signal and the magnetic field excitation signal is equal to the expected phase difference, thereby completing the phase closed-loop control of the magnetic resonance signal.

[0065] In summary, the present invention provides a low-power, high-precision magnetic resonance signal phase closed-loop control method and system. First, a low-power DDS chip generates a magnetic field excitation signal to excite the alkali metal atoms in the atomic gas chamber, and generates two orthogonal reference signals for extracting the phase information of the magnetic resonance signal; then the magnetic resonance signal and the reference signal are simultaneously sent to the analog multiplier, and low-pass filtered to extract the phase information of the magnetic resonance signal; then, through phase compensation, the phase lag and drift in the system are suppressed; finally, through PID control, the output frequency of the DDS chip is changed to achieve closed-loop control of the phase. The present invention realizes closed-loop control of the magnetic resonance signal phase, greatly reduces system power consumption, suppresses phase temperature drift, improves magnetic field measurement stability, and ensures the environmental adaptability of the system. .

[0066] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0067] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low-power, high-precision magnetic resonance signal phase closed-loop control method, characterized in that: The low-power, high-precision magnetic resonance signal phase closed-loop control method comprises: The DDS chip generates a magnetic field excitation signal and two reference signals with a phase difference of 90°; Multiplying the magnetic resonance signal with two reference signals by an analog multiplier to obtain an output result of the analog multiplier, and performing low-pass filtering on the output result to obtain two-way filtered output results; The two-way filtering output results are collected by a low-power ADC chip, and the two-way filtering output results are divided and simplified to obtain the phase difference between the magnetic resonance signal and the reference signal; Calculating and acquiring a phase difference between the magnetic resonance signal and the magnetic field excitation signal according to the phase difference between the magnetic resonance signal and the reference signal; Performing phase compensation on the phase difference between the magnetic resonance signal and the magnetic field excitation signal; The phase difference between the phase-compensated magnetic resonance signal and the magnetic field excitation signal is compared with the expected phase difference, and the difference between the phase difference between the phase-compensated magnetic resonance signal and the magnetic field excitation signal and the expected phase difference is substituted into the PID closed-loop control algorithm to obtain the change in the frequency of the excitation signal, and the output frequency of the DDS chip is changed until the phase difference between the phase-compensated magnetic resonance signal and the magnetic field excitation signal is equal to the expected phase difference, thereby completing the closed-loop control of the magnetic resonance signal phase.

2. The low-power, high-precision magnetic resonance signal phase closed-loop control method according to claim 1, characterized in that: The magnetic field excitation signal x A The expression is x A =Asin(ωt+θ A ), the reference signal x B ,x C The expression is Where A is the amplitude of the magnetic field excitation signal, ω is the signal frequency, t is the time, θ A is the phase of the magnetic field excitation signal, B is the signal amplitude, θ B ,θ C is the phase of the two reference signals, and the phase difference is 90°.

3. The low-power, high-precision magnetic resonance signal phase closed-loop control method according to claim 2, characterized in that: The expression of the magnetic resonance signal after the atoms in the atomic gas chamber resonate is x D =Dsin(ωt+θ D ), where D is the magnetic resonance signal amplitude, ω is the signal frequency, t is the time, θ D is the magnetic resonance signal phase.

4. The low-power, high-precision magnetic resonance signal phase closed-loop control method according to claim 3, characterized in that: The output of the analog multiplier is Y B , Y C It is the output result of the analog multiplier, which is the superposition of the DC component and the high-frequency AC component.

5. The low-power, high-precision magnetic resonance signal phase closed-loop control method according to claim 4, characterized in that: Two-way filtering output result Y′ B , Y′ C The expression is 6. The low-power, high-precision magnetic resonance signal phase closed-loop control method according to claim 5, characterized in that: The phase difference between the magnetic resonance signal and the reference signal is θ D -θ B =acot(Y).

7. The low-power, high-precision magnetic resonance signal phase closed-loop control method according to claim 6, characterized in that: The phase difference between the magnetic resonance signal and the magnetic field excitation signal is Among them, θ A-B It is the phase difference between the reference signal and the simulated excitation signal, which can be measured and solved and is a constant.

8. The low-power, high-precision magnetic resonance signal phase closed-loop control method according to claim 7, characterized in that: The phase difference between the magnetic resonance signal and the magnetic field excitation signal after phase compensation is θ=Φ(θ D-A ,T).

9. A low-power, high-precision magnetic resonance signal phase closed-loop control system, characterized in that: The low-power, high-precision magnetic resonance signal phase closed-loop control system uses the low-power, high-precision magnetic resonance signal phase closed-loop control method as described in claims 1 to 8 to perform magnetic resonance signal phase closed-loop control.

10. The low-power, high-precision magnetic resonance signal phase closed-loop control system according to claim 9, characterized in that: The low-power, high-precision magnetic resonance signal phase closed-loop control system comprises a DDS chip, an atomic gas chamber, an analog multiplier, a low-pass filter, a low-power ADC chip and a low-power ARM processor, wherein the DDS chip is used to generate a magnetic field excitation signal and two reference signals with a phase difference of 90°, the analog multiplier is used to multiply the magnetic resonance signal output by the atomic gas chamber with the two reference signals to obtain an output result of the analog multiplier, the low-pass filter is used to perform low-pass filtering on the output result to obtain two-way filtered output results, and the low-power ADC chip is used to collect the two-way filtered output results; The low-power ARM processor is used to divide and simplify the output results of the two filters to obtain the phase difference between the magnetic resonance signal and the reference signal, calculate the phase difference between the magnetic resonance signal and the magnetic field excitation signal according to the phase difference between the magnetic resonance signal and the reference signal, perform phase compensation on the phase difference between the magnetic resonance signal and the magnetic field excitation signal, compare the phase difference between the magnetic resonance signal and the magnetic field excitation signal after phase compensation with the expected phase difference, substitute the difference between the phase difference between the magnetic resonance signal and the magnetic field excitation signal after phase compensation and the expected phase difference into the PID closed-loop control algorithm, obtain the change in the frequency of the excitation signal, change the output frequency of the DDS chip until the phase difference between the magnetic resonance signal and the magnetic field excitation signal after phase compensation is equal to the expected phase difference, and complete the phase closed-loop control of the magnetic resonance signal.

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