CN-122017701-A - Nuclear magnetic resonance gyroscope main magnetic field measuring method based on rotating magnetic field phase compensation

CN122017701ACN 122017701 ACN122017701 ACN 122017701ACN-122017701-A

Abstract

The invention provides a nuclear magnetic resonance gyroscope main magnetic field measuring method based on rotating magnetic field phase compensation, which comprises the steps of separating magnetic resonance signals of 129Xe nuclear spin and 131Xe nuclear spin in a nuclear magnetic resonance gyroscope, demodulating frequencies of the separated 129Xe nuclear spin magnetic resonance signals and 131Xe nuclear spin magnetic resonance signals respectively by utilizing a high-speed digital phase-locked loop, carrying out summation operation on the two demodulated frequencies to obtain a sum frequency measuring signal, synthesizing a rotating magnetic field for generating a simulated nuclear spin magnetic resonance, measuring coupling phase errors generated when the nuclear spin magnetic resonance signals are measured by using electron spin to obtain an error compensation quantity, and carrying out differential operation on the error compensation quantity and the sum frequency measuring signal to obtain an accurate value of a main magnetic field to be measured. By applying the technical scheme of the invention, the technical problem that the main magnetic field measurement accuracy is low because of the difficulty in effectively inhibiting the differential mode error caused by the precession phase coupling of paramagnetic resonance electron spin and nuclear spin in the prior art is solved.

Inventors

QIN JIE
HUANG JIONG
WAN SHUANGAI
WEI KEQUAN
PAN YUHANG
HAN JUNLONG

Assignees

北京自动化控制设备研究所

Dates

Publication Date: 20260512
Application Date: 20251230

Claims (10)

1. The nuclear magnetic resonance gyro main magnetic field measuring method based on the rotating magnetic field phase compensation is characterized by comprising the following steps of: Demodulating magnetic resonance signals of 129 Xe nuclear spin and 131 Xe nuclear spin in a nuclear magnetic resonance gyroscope based on paramagnetic resonance modulation and carrier demodulation of electron spin, and separating the magnetic resonance signals of the two nuclear spin by a filtering signal processing method; Demodulating the frequencies of the separated 129 Xe nuclear spin magnetic resonance signals and 131 Xe nuclear spin magnetic resonance signals by using a high-speed digital phase-locked loop, and carrying out summation operation on the two demodulated frequencies to obtain a sum frequency measurement signal; Step three, utilizing an x-axis magnetic field coil and a y-axis magnetic field coil to apply sine line magnetic fields which have the same frequency and different frequencies from the nuclear spin magnetic resonance signals and have the phase difference of 90 degrees on the x-axis and the y-axis respectively, and synthesizing to generate a rotating magnetic field simulating the nuclear spin magnetic resonance; measuring the phase and frequency change of the rotating magnetic field generated in the third step through paramagnetic resonance electron spin, so as to realize the measurement of coupling phase errors generated when the electron spin measures nuclear spin magnetic resonance signals and obtain an error compensation quantity; and fifthly, carrying out differential operation on the error compensation quantity measured in the fourth step and the sum frequency measurement signal obtained in the second step, so as to inhibit the coupling phase error, and calculating to obtain an accurate value of the main magnetic field to be measured, thereby completing the measurement of the main magnetic field of the nuclear magnetic resonance gyroscope.
2. The method for measuring the main magnetic field of the nuclear magnetic resonance gyroscope based on phase compensation of a rotating magnetic field according to claim 1, wherein the method specifically comprises the steps of starting the nuclear magnetic resonance gyroscope to enable 129 Xe nuclear spin and 131 Xe nuclear spin in a magnetic resonance state, modulating nuclear spin magnetic resonance signals based on a paramagnetic resonance modulation technology of electron spin, demodulating the modulated signals through a carrier demodulation circuit to obtain mixed signals containing 129 Xe and 131 Xe nuclear spin magnetic resonance signals, inputting the mixed signals into a filter circuit, and separating the mixed signals into 129 Xe nuclear spin magnetic resonance signals and 131 Xe nuclear spin magnetic resonance signals according to frequency difference of the two nuclear spin magnetic resonance signals.
3. The method for measuring the main magnetic field of the nuclear magnetic resonance gyroscope based on phase compensation of a rotating magnetic field according to claim 2, wherein the second step specifically comprises the steps of connecting a separated 129 Xe nuclear spin magnetic resonance signal to a first high-speed digital phase-locked loop, connecting a separated 131 Xe nuclear spin magnetic resonance signal to a second high-speed digital phase-locked loop, demodulating the frequencies of input signals by the two high-speed digital phase-locked loops respectively to obtain a demodulated 129 Xe nuclear spin magnetic resonance frequency f 1 and a demodulated 131 Xe nuclear spin magnetic resonance frequency f 2 , inputting the demodulated 129 Xe nuclear spin magnetic resonance frequency f 1 and the demodulated 131 Xe nuclear spin magnetic resonance frequency f 2 to a summation operation circuit to obtain a sum frequency measurement signal f_sum=f 1 +f 2 , wherein the sum frequency measurement signal f_sum has the effect of eliminating an angular rate omega, and suppressing a resonance frequency measurement difference modulus error delta f_d caused by a coupling phase change when paramagnetic electron spin measurement nuclear spin precession.
4. A nuclear magnetic resonance gyro main magnetic field measurement method based on phase compensation of a rotating magnetic field according to claim 3, wherein the sum frequency measurement signal f_sum is calculated and obtained according to f_sum= (γ 1 +γ 2 )B 0 +2Δf_c+2Δf_n, wherein γ 1 、γ 2 is the gyromagnetic ratio of 129 Xe and 131 Xe nuclear spins, Δf_c is the magnetic resonance frequency measurement common mode coupling phase error caused by the coupling phase change during the nuclear spin precession of paramagnetic resonance electron spin measurement, Δf_n is the coupling phase error caused by the detection noise during the detection of the electron spin precession signal by the optical rotation effect of the detection light, and B 0 is the main magnetic field to be measured.
5. The method for measuring the main magnetic field of the nuclear magnetic resonance gyroscope based on the phase compensation of the rotating magnetic field according to claim 4, wherein the third step specifically comprises the steps of generating two paths of sinusoidal signals through a signal generator, wherein one path of sinusoidal signals is input to an x-axis magnetic field coil driving circuit and drives the x-axis magnetic field coil to generate a sinusoidal line magnetic field Bx=B 0 x sin (2pi ft) in the x-axis direction, the other path of sinusoidal signals is input to a y-axis magnetic field coil driving circuit after passing through a 90-degree phase shifting circuit and drives the y-axis magnetic field coil to generate a sinusoidal line magnetic field By=B 0 y cos (2pi ft) in the y-axis direction, f is sinusoidal signal frequency, the sinusoidal signal frequency f is different from 129 Xe、 131 Xe nuclear spin magnetic resonance signal frequency, B 0 x、B 0 y is the amplitudes of the x-axis sinusoidal line magnetic field and the y-axis sinusoidal line magnetic field respectively, and the b_rot is generated through combination.
6. The method for measuring the main magnetic field of the nuclear magnetic resonance gyro based on the phase compensation of the rotating magnetic field according to claim 5, wherein the fourth step comprises the steps of detecting the precession signal of the electron spin by detecting the optical rotation effect of light (along the x-axis direction) after the paramagnetic resonance electron spin senses the rotating magnetic field B_rot, inputting the signal to the signal processing unit, analyzing the phase and frequency changes of the rotating magnetic field B_rot, and calculating the acquisition error compensation amount Δf_comp by combining a pre-calibrated coefficient K.
7. The method of claim 6, wherein in the fifth step, the main magnetic field B 0 to be measured is calculated according to B 0 ＝f_final/(γ 1 +γ 2 ), and f_final is a difference between the sum frequency measurement signal f_sum and the error compensation amount Δf_comp.
8. A nuclear magnetic resonance gyro main magnetic field measurement system based on rotating magnetic field phase compensation, characterized in that the nuclear magnetic resonance gyro main magnetic field measurement system based on rotating magnetic field phase compensation is used for realizing the nuclear magnetic resonance gyro main magnetic field measurement method based on rotating magnetic field phase compensation as claimed in claims 1 to 7.
9. The rotating field phase compensation-based nuclear magnetic resonance gyro main magnetic field measurement system according to claim 8, characterized in that the rotating field phase compensation-based nuclear magnetic resonance gyro main magnetic field measurement system comprises: The signal demodulation and separation module is used for demodulating magnetic resonance signals of 129 Xe nuclear spin and 131 Xe nuclear spin based on paramagnetic resonance modulation and carrier demodulation of electron spin, and separating the magnetic resonance signals of the two nuclear spin through a filtering signal processing method; The frequency demodulation and preliminary operation module comprises a high-speed digital phase-locked loop and a summation operation unit, wherein the high-speed digital phase-locked loop is used for demodulating the frequencies of the two separated nuclear spin magnetic resonance signals, and the summation operation unit is used for summing the two demodulation frequencies to obtain a preliminary sum frequency measurement signal; The rotating magnetic field generating module consists of a signal generator, a 90-degree phase shifting circuit, an x-axis magnetic field coil driving circuit, a y-axis magnetic field coil driving circuit, an x-axis magnetic field coil and a y-axis magnetic field coil, wherein the signal generator outputs two paths of sine signals with the same frequency, one path of sine signals is directly input into the x-axis magnetic field coil driving circuit, the other path of sine signals is input into the y-axis magnetic field coil driving circuit after passing through the 90-degree phase shifting circuit, and the x-axis magnetic field coil and the y-axis magnetic field coil generate sine line magnetic fields under the action of the x-axis magnetic field coil driving circuit and the y-axis magnetic field coil driving circuit respectively to synthesize a rotating magnetic field; The coupling phase error measurement module is used for measuring the phase and frequency change of the rotating magnetic field through paramagnetic resonance electron spin to obtain an error compensation quantity; The phase compensation and accurate measurement module is used for carrying out differential operation on the error compensation quantity and the sum frequency measurement signal, so as to inhibit the error of the coupling phase difference module and output an accurate main magnetic field measurement signal.
10. The nuclear magnetic resonance gyro main magnetic field measurement system based on phase compensation of a rotating magnetic field according to claim 9, wherein the coupling phase error measurement module comprises a detection light emitting unit, a light detecting unit and an error calculating unit, the detection light emitting unit emits detection light along the x-axis direction, the light detecting unit detects the rotation change of the light after passing through a medium containing nuclear spins and electron spins to obtain an electron spin precession signal, and the error calculating unit processes the signal, analyzes the phase and frequency changes of the rotating magnetic field, and calculates an error compensation amount.

Description

Nuclear magnetic resonance gyroscope main magnetic field measuring method based on rotating magnetic field phase compensation Technical Field The invention relates to the technical field of nuclear magnetic resonance gyroscopes, in particular to a nuclear magnetic resonance gyroscopes main magnetic field measuring method based on rotating magnetic field phase compensation. Background In the working process of the nuclear magnetic resonance gyroscope, the accurate measurement of the main magnetic field is very important, and the measurement accuracy directly influences the overall performance of the nuclear magnetic resonance gyroscope. The conventional main magnetic field measurement method is generally based on nuclear spin magnetic resonance signals, but in practical application, various error factors exist to influence measurement accuracy. On the one hand, the precession phase coupling of the electron spin and the nuclear spin of paramagnetic resonance can cause errors in the measurement of the magnetic resonance frequency, and on the other hand, the difference exists in the induced spin polarization magnetic field of the electron due to the Fermi contact interaction of the nuclear spin of different types (such as 129 Xe and 131 Xe), and the errors are further introduced. In addition, in the process of detecting the electron spin precession signal by the detection light through the optical rotation effect, the detection noise floor can cause a relative solution error of the frequency of the magnetic resonance signal, the error is related to the signal to noise ratio, and the error can be obviously increased under the condition of non-ideal signal to noise ratio. Although the influence of angular velocity can be eliminated and common mode errors can be restrained to a certain extent by carrying out summation operation on two nuclear spin magnetic resonance frequencies, for the differential mode errors caused by coupling phase change during nuclear spin precession of paramagnetic resonance electron spin measurement, the traditional method is difficult to effectively restrain, so that the measurement precision of a main magnetic field cannot meet the application requirement of a high-precision nuclear magnetic resonance gyroscope. Therefore, a method and system for effectively suppressing the above-mentioned differential mode error and improving the measurement accuracy of the main magnetic field are needed. Disclosure of Invention The invention provides a nuclear magnetic resonance gyroscope main magnetic field measurement method based on rotating magnetic field phase compensation, which can solve the technical problem that in the prior art, the difference mode error caused by paramagnetic resonance electron spin and nuclear spin precession phase coupling is difficult to effectively inhibit, so that the main magnetic field measurement precision is low. According to one aspect of the invention, a nuclear magnetic resonance gyro main magnetic field measuring method based on rotating magnetic field phase compensation is provided, the nuclear magnetic resonance gyro main magnetic field measuring method based on rotating magnetic field phase compensation comprises the steps of firstly demodulating magnetic resonance signals of 129 Xe nuclear spin and 131 Xe nuclear spin in a nuclear magnetic resonance gyro based on paramagnetic resonance modulation and carrier demodulation of electron spin, separating the magnetic resonance signals of the two nuclear spin through a filtering signal processing method, secondly demodulating the frequencies of the separated 129 Xe nuclear spin magnetic resonance signals and 131 Xe nuclear spin magnetic resonance signals respectively through a high-speed digital phase-locked loop, carrying out summation operation on the two demodulated frequencies to obtain a sum frequency measuring signal, thirdly applying sine line magnetic fields which have the same phase difference of 90 DEG and different frequency from the nuclear spin magnetic resonance signals on the x axis and the y axis respectively, synthesizing to generate a rotating magnetic field simulating nuclear spin resonance, fourthly realizing phase and frequency change of the rotating magnetic field generated in the third step of the electronic spin measurement, realizing the difference between the two demodulated frequencies and the main magnetic resonance signals, and obtaining a difference value of the difference between the measured magnetic resonance signals, and the difference value of the difference between the measured magnetic field and the main magnetic resonance signals is obtained, and the error of the measured error is accurately calculated, and the error is obtained in the step of measuring the phase difference measurement. The method comprises the steps of starting a nuclear magnetic resonance gyroscope to enable 129 Xe nuclear spin and 131 Xe nuclear spin in a magnetic resonance state, modulating nuclear spin ma