CN110333545A - Improve the system and method for rotary proton class sensor tuning precision and signal-to-noise ratio - Google Patents
Improve the system and method for rotary proton class sensor tuning precision and signal-to-noise ratio Download PDFInfo
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Abstract
The present invention provides the system and methods for improving rotary proton class sensor tuning precision and signal-to-noise ratio, the present invention uses the tuning that rotary proton class sensor is realized by the method that PCA algorithm, svd algorithm and fft algorithm combine, and effectively overcoming existing tuning algorithm tuned speed, tuning precision is low slowly, under interference environment, the defects of detuning phenomena easily occurs；While reducing tuning period, improve the tuning precision of rotary proton class sensor, selection of the Wide measuring range to tuning capacitance can be achieved, improve the signal-to-noise ratio of later period measuring signal, applied to rotary proton class magnetometer, optical pumped magnetometer and nuclear magnetic resonance rotary proton FID signal imager etc. by the instrument of rotary proton class sensor, instrument performance is effectively improved.
Description
Technical field
The present invention relates to weak magnetic fields measurement technical fields, and in particular to improve rotary proton class sensor tuning precision and
The system and method for signal-to-noise ratio.
Background technique
Rotary proton class magnetometer is a kind of for measuring the magnetic-field measurement of slowly varying low-intensity magnetic field or System for Low DC Magnetic Field field
Instrument, sensor, that is, rotary proton class sensor are inductance element.Measuring principle is using certain shooting condition by inductance
Proton in the solution be active, proton can be drawn around external magnetic field i.e. earth magnetic field is stablized after removing shooting condition
More's precessional motion, generates FID (Free Induction Decay) signal, and precession frequency is proportional to external magnetic field；Therefore it is sharp
FID signal is incuded with inductance, is amplified, shaping and measures frequency, external magnetic field value can be obtained.With other magnetic-field measurements
Technology is compared, and rotary proton class magnetometer has the characteristics that high-precision, high sensitivity, is widely used and space exploration, near-earth
The fields such as table detection, hydrospace detection, geomagnetic field measuring, military technology.Since the signal-to-noise ratio of FID signal is to measure frequency-measurement accuracy
Therefore key factor to increase the signal-to-noise ratio that sensor exports FID signal, improves frequency-measurement accuracy, need to be by variable capacitance and sensing
Device is in parallel, is tuned, this variable capacitance is tuning capacitance.
Currently, the sensor that most rotary proton class magnetometers use tune scheme for scanning method, preset capacitance method,
Blindly automatically track method and double measurement automatic follow-up tuning method.And the methodical core operating principle of institute is identical: excitation sensing
Device, switches tuning capacitance, the crest voltage of detection output FID signal, and corresponding tuning capacitance capacitance is just at maximum peak voltage
It is the values for tuning of sensor；Only difference is that the means of detection crest voltage.Chinese patent CN103995298A is announced
A kind of optimum choice proton magnetometer matches the method for humorous capacitor, in that patent, it is first determined a fixed tuning capacitance
Then capacitance is gradually adjusted to determine final tuning capacitance capacitance.
There are still following problems in the design of sensor tuning algorithm for existing rotary proton class magnetometer: 1) tuning speed
Degree is universal relatively slow, about needs several seconds, when the actual measurement of field, when change of magnetic field strength is larger, generally requires again to biography
Sensor is tuned, and brings big inconvenience to user；2) humorous FID signal pole is not matched due to the output of rotary proton class magnetometer
Its is faint, it is easy to be interfered by noise signal, noise is relatively low, once instrument, which is in, interferes biggish environment, frequency spectrum easily occurs
Analytical error is larger to be caused " to lack of proper care ", and instrument is caused to can not work normally.
Summary of the invention
The technical problem to be solved in the present invention is that for above-mentioned existing rotary proton class magnetometer at present in sensor
Technical problem present on the design of tuning algorithm provides the system for improving rotary proton class sensor tuning precision and signal-to-noise ratio
And method solves above-mentioned technological deficiency.
The system for improving rotary proton class sensor tuning precision and signal-to-noise ratio, including dynamical nuclear polarization weak magnetic sensor,
High-frequency oscillating circuits, direct-flow impulse circuit, tuning circuit, amplifying circuit, narrow-band filtering circuit, hysteresis comparator circuit, ADC acquisition
Device, constant-temperature crystal oscillator, FPGA digital Frequency Measuring module and STM32；High-frequency oscillating circuits and direct-flow impulse circuit collectively constitute excitation electricity
Road；
Dynamical nuclear polarization sensor receives the pumping signal of high-frequency oscillating circuits and direct-flow impulse circuit, induces FID letter
Number, and pass to tuning circuit；After tuning circuit is tuned signal, amplifying circuit is passed to；Amplifying circuit to signal into
After row amplification, it is delivered separately to narrow-band filtering circuit, hysteresis comparator circuit and ADC collector；Narrow band filter is to letter
Number carry out bandpass filtering after, be transmitted to hysteresis comparator circuit；After hysteresis comparator circuit carries out shaping to signal, transmitted
Later period signal processing is carried out to FPGA；ADC collector is connect with STM32, carries out the acquisition and processing of data；STM32 and high frequency
Oscillating circuit is connected with direct-flow impulse circuit, controls the open and close of pumping signal；STM32 is connect with FPGA, to FID signal
Carry out frequency measurement；STM32 is connected with narrow band filter, adjusts its narrow band center frequency；Constant-temperature crystal oscillator is connected with FPGA.
Further, STM32 is for driving high-frequency oscillating circuits and direct-flow impulse circuit stimulus sensor to export the first FID
Signal, waits preset time after the completion of excitation, driving ADC collector acquires first FID signal, generates discrete data；Root
Space matrix is constructed according to the discrete data, and principal component is carried out to the space matrix using PCA algorithm and svd algorithm respectively
Separation and singular value decomposition obtain reconstruct data with cancelling noise；The reconstruct data are handled using fft algorithm, described in acquisition
The corresponding first frequency value of maximum peak voltage in first FID signal frequency spectrum；By the inductance value of the sensor and described first
Frequency values substitute into LC resonance equations first capacitor value, and drive tuning circuit by the tuning capacitance with the sensor parallel
Capacitance be switched to the first capacitor value by zero；
It is also used to that exciting circuit stimulus sensor is driven to export the second FID signal again, waits after the completion of excitation default
Time, driving FPGA measure the second frequency value of second FID signal；By the inductance value of the sensor and second frequency
Rate value substitutes into the second capacitance of LC resonance equations, and drives tuning circuit by the capacitance of the tuning capacitance by described first
Capacitance is switched to second capacitance；
It is also used to that exciting circuit stimulus sensor is driven to export third FID signal again；It is also used to the narrowband
The centre frequency of filter circuit is set as the second frequency value；Its third for being also used to that FPGA is driven to measure after shaping
The third frequency values of FID signal, and the frequency of the FID signal detected using the third frequency values as the sensor is defeated
Out.
Further, high-frequency oscillating circuits is used for the stimulus sensor under the driving of STM32 and exports the first FID signal；Its
It is also used to the stimulus sensor under the driving of the STM32 and exports the second FID signal；It is also used to the driving in the STM32
Lower stimulus sensor exports third FID signal；
Direct-flow impulse circuit is used for the stimulus sensor under the driving of STM32 and exports the first FID signal；It is also used in institute
It states stimulus sensor under the driving of STM32 and exports the second FID signal；It is also used to motivate sensing under the driving of the STM32
Device exports third FID signal.
Further, tuning circuit is used for the appearance of the tuning capacitance with the sensor parallel under the driving of STM32
Value is switched to the first capacitor value by zero；It is also used under the driving of the STM32 by the capacitance of the tuning capacitance by
The first capacitor value is switched to second capacitance；It is also used to the tuning capacitance under the driving of the STM32
Capacitance the third capacitance is switched to by second capacitance.
Further, the first FID signal is amplified, is used for waiting preset time after the completion of motivating by amplifying circuit
It is acquired in the collector；It is also used to wait preset time after the completion of motivating, and the second FID signal is amplified, for slow
Stagnant comparison circuit shaping；It is also used to wait preset time after the completion of motivating, and amplifies, is used for the third FID signal
The narrow-band filtering circuit filtering；Narrow-band filtering circuit be used for centered on second frequency value frequency to amplified third
FID signal is filtered, and is used for hysteresis comparator circuit shaping.
Further, hysteresis comparator circuit is used to amplified second FID signal carrying out shaping, measures for FPGA,
It is also used to carry out shaping to the filtered third FID signal, measures for the FPGA；ADC collector is used for
First FID signal is acquired under the driving of STM32, generates discrete data.
Further, FPGA digital Frequency Measuring module under the driving of the STM32 for measuring the second of the second FID signal
Frequency values, the third frequency values of the third FID signal after being also used to measure shaping.
Further, constant-temperature crystal oscillator is for generating stable oscillator signal, and the standard as FPGA digital Frequency Measuring module
Technology frequency values use.
The method for improving rotary proton class sensor tuning precision and signal-to-noise ratio, based on raising rotary proton class sensor tune
Humorous precision and the system of signal-to-noise ratio are realized, comprising:
S1, high-frequency oscillating circuits and direct-flow impulse circuit is driven to motivate dynamical nuclear polarization sensor 400ms using STM32,
The first FID signal is exported, and signal is passed into tuning circuit, tuning circuit passes it to ADC acquisition after amplifying signal
Device；
After the completion of S2, the sample rate that ADC collector is set, sampling number, acquisition signal time, frequency resolution and excitation
Preset time is waited, first FID signal is acquired using the ADC set, generates discrete data, and send data to
STM32；
S3, space matrix is constructed according to the discrete data using STM32, and using PCA and svd algorithm to the space
Matrix carries out principal component separation and singular value decomposition respectively with cancelling noise, obtains reconstruct data；
S4, in STM32, the reconstruct data are handled using fft algorithm, are obtained in the first FID signal frequency spectrum most
The corresponding first frequency value of big crest voltage；
S5, in STM32, the inductance value of the sensor and the first frequency value are substituted into LC resonance equations the
One capacitance, and described the is switched to by zero using STM32 driving and the capacitance in the tuning circuit of the sensor parallel
One capacitance；
S6, high-frequency oscillating circuits and direct-flow impulse circuit are driven using STM32, again stimulus sensor 100ms output the
Two FID signals wait preset time after the completion of excitation, and transmit a signal to tuning circuit, transmit a signal to after tuned
Signal after shaping is transmitted signal progress shaping by amplifying circuit, the amplified hysteresis comparator circuit that transmits a signal to
To FPGA；The second frequency value of second FID signal is obtained using FPGA；By the inductance value of the sensor and described second
Frequency values substitute into the second capacitance of LC resonance equations, and utilize the tuning circuit of STM32 driving and the sensor parallel
In capacitance second capacitance is switched to by the first capacitor value；
S7, high-frequency oscillating circuits and direct-flow impulse circuit are driven using STM32, again stimulus sensor 100ms output the
Three FID signals wait preset time after the completion of excitation, and transmit a signal to tuning circuit, transmit a signal to after tuned
Amplifying circuit；Narrow-band filtering circuit is driven using STM32, using the second frequency value as its centre frequency to by amplification electricity
The third FID signal behind road is filtered, and by the filtered third FID signal be transmitted to hysteresis comparator circuit into
Row shaping, and the signal after shaping is transmitted to FPGA；The third frequency of the third FID signal after shaping is obtained using FPGA
Rate value, and the frequency for the FID signal that the third frequency values are detected as the sensor.
Further, step S3 is specifically included:
S31, STM32 drive high-frequency oscillating circuits and direct-flow impulse circuit first time stimulus sensor to generate the first FID letter
After number, it is amplified by amplifying circuit, then it is recorded using ADC collector, obtains discrete data x=
[x1,x2,…,xn], and it is transmitted to STM32；
S32, new space matrix m is constructed using STM32:
S33, in STM32, using PCA algorithm to space matrix m carry out principal component analysis, by purified signal and noise
Signal is separated, to obtain new discrete data x '=[x1’,x2’,…,xn']；
S34, new space matrix Σ is constructed using STM32:
S35, in STM32, use svd algorithm to the space matrix Σ carry out singular value decomposition with it is further rejecting make an uproar
Sound obtains reconstruct data.
Compared with prior art, the beneficial effects of the present invention are:
1, using PCA algorithm in such a way that svd algorithm combines, inhibit to be attached on FID signal on software view
Unknown noise；
2, using program-controlled narrow-band filtering wave circuit, making an uproar outside FID signal center frequency-band is further suppressed on hardware view
Sound；
3, by the tuning manner of soft or hard combination, effectively overcome that existing tuning algorithm tuned speed is slow, under interference environment
Tuning precision is low, the defects of detuning phenomena easily occurs；
4, frequency measurement and signal processing system are made of digital circuit, can be integrated in FPGA and STM32, it is easy to accomplish
And high reliablity, corresponding software overlap joint and chip selection can be adjusted according to the actual situation, reduce improvement cost.
Detailed description of the invention
Present invention will be further explained below with reference to the attached drawings and examples, in attached drawing:
Fig. 1 is the system construction drawing of raising rotary proton class sensor tuning precision and signal-to-noise ratio of the invention；
Fig. 2 is tuning circuit figure of the invention；
Fig. 3 is the method flow diagram of raising rotary proton class sensor tuning precision and signal-to-noise ratio of the invention；
Fig. 4 is filter effect of embodiment of the present invention comparison diagram.
Specific embodiment
For a clearer understanding of the technical characteristics, objects and effects of the present invention, now control attached drawing is described in detail
A specific embodiment of the invention.
The system for improving rotary proton class sensor tuning precision and signal-to-noise ratio, as shown in Figure 1, including that dynamical nuclear polarization is weak
Magnetic Sensor, high-frequency oscillating circuits, direct-flow impulse circuit, tuning circuit, amplifying circuit, narrow-band filtering circuit, sluggishness are more electric
Road, ADC collector (Analog-to-Digital Converter), constant-temperature crystal oscillator, FPGA digital Frequency Measuring module (Field
Programmable Gate Array, field programmable gate array), STM32；High-frequency oscillating circuits and direct-flow impulse circuit are total
With composition exciting circuit.
Dynamical nuclear polarization sensor receives the pumping signal of high-frequency oscillating circuits and direct-flow impulse circuit, induces FID letter
Number, and pass to tuning circuit；After tuning circuit is tuned signal, amplifying circuit is passed to；Amplifying circuit to signal into
After row amplification, it is delivered separately to narrow-band filtering circuit, hysteresis comparator circuit and ADC collector；Narrow band filter is to letter
Number carry out bandpass filtering after, be transmitted to hysteresis comparator circuit；After hysteresis comparator circuit carries out shaping to signal, transmitted
Later period signal processing is carried out to FPGA；ADC collector is connect with STM32, carries out the acquisition and processing of data；STM32 and high frequency
Oscillating circuit is connected with direct-flow impulse circuit, controls the open and close of pumping signal；STM32 is connect with FPGA, to FID signal
Carry out frequency measurement；STM32 is connected with narrow band filter, adjusts its narrow band center frequency；Constant-temperature crystal oscillator is connected with FPGA,
To ensure the validity and stability of its reference frequency value.
STM32 is for driving high-frequency oscillating circuits and direct-flow impulse circuit (the two is referred to as are as follows: exciting circuit) excitation sensing
Device exports the first FID signal, preset time is waited after the completion of excitation, driving ADC collector acquires first FID signal, raw
At discrete data；Space matrix is constructed according to the discrete data, and using PCA algorithm and svd algorithm to the space matrix
It carries out principal component separation and singular value decomposition respectively with cancelling noise, obtains reconstruct data；The reconstruct is handled using fft algorithm
Data obtain the corresponding first frequency value of maximum peak voltage in the first FID signal frequency spectrum；By the inductance of the sensor
Value and the first frequency value substitute into LC resonance equations first capacitor value, and drive tuning circuit will be with the sensor simultaneously
The capacitance of the tuning capacitance of connection is switched to the first capacitor value by zero；
It is also used to that exciting circuit stimulus sensor is driven to export the second FID signal again, waits after the completion of excitation default
Time, driving FPGA measure the second frequency value of second FID signal；By the inductance value of the sensor and second frequency
Rate value substitutes into the second capacitance of LC resonance equations, and drives tuning circuit by the capacitance of the tuning capacitance by described first
Capacitance is switched to second capacitance；
It is also used to that exciting circuit stimulus sensor is driven to export third FID signal again；It is also used to the narrowband
The centre frequency of filter circuit is set as the second frequency value；Its third for being also used to that FPGA is driven to measure after shaping
The third frequency values of FID signal, and the frequency of the FID signal detected using the third frequency values as the sensor is defeated
Out.
High-frequency oscillating circuits is used for the stimulus sensor under the driving of STM32 and exports the first FID signal；It is also used in institute
It states stimulus sensor under the driving of STM32 and exports the second FID signal；It is also used to motivate sensing under the driving of the STM32
Device exports third FID signal.
Direct-flow impulse circuit is used for the stimulus sensor under the driving of STM32 and exports the first FID signal；It is also used in institute
It states stimulus sensor under the driving of STM32 and exports the second FID signal；It is also used to motivate sensing under the driving of the STM32
Device exports third FID signal.
Tuning circuit is used for the capacitance of the tuning capacitance with the sensor parallel under the driving of STM32 by zero switching
For the first capacitor value；It is also used to the capacitance of the tuning capacitance under the driving of the STM32 by first electricity
Capacitance is switched to second capacitance；It is also used to the capacitance of the tuning capacitance under the driving of the STM32 by institute
It states the second capacitance and is switched to the third capacitance.The switching that tuning capacitance is realized using scheme as shown in Figure 2, reaches
The purpose of tuning selects the rule of capacitor to be:
Using capacitor selected by above formula, and by the various combinations of 10 analog switches, finally may be implemented in 1nF~
Within the scope of 1023nF, resolution ratio 1nF, capacitance is arbitrarily adjustable, to meet the measurement range in earth's magnetic field.
First FID signal is amplified for waiting preset time after the completion of motivating, is used for the acquisition by amplifying circuit
Device acquisition；It is also used to wait preset time after the completion of motivating, and the second FID signal is amplified, hysteresis comparator circuit is used for
Shaping；It is also used to wait preset time after the completion of motivating, and amplifies to the third FID signal, filters for the narrowband
Wave circuit filtering.
Narrow-band filtering circuit is used for the frequency centered on second frequency value and filters to amplified third FID signal
Wave is used for hysteresis comparator circuit shaping；
Hysteresis comparator circuit is used to amplified second FID signal carrying out shaping, measures for FPGA；It is also used to pair
The filtered third FID signal carries out shaping, measures for the FPGA.
ADC collector generates discrete data for acquiring first FID signal under the driving of STM32.
FPGA digital Frequency Measuring module is used to measure the second frequency value of the second FID signal under the driving of the STM32；Its
The third frequency values of third FID signal after being also used to measure shaping.
Constant-temperature crystal oscillator is for generating stable oscillator signal, and the standard technique frequency values as FPGA digital Frequency Measuring module
It uses.
The method for improving rotary proton class sensor tuning precision and signal-to-noise ratio, as shown in Figure 3, comprising:
S1, high-frequency oscillating circuits and direct-flow impulse circuit is driven to motivate dynamical nuclear polarization sensor 400ms using STM32,
The first FID signal is exported, and signal is passed into tuning circuit, tuning circuit passes it to ADC acquisition after amplifying signal
Device；
S2, exponentially decay due to FID signal, it is therefore necessary to which suitable A/D sample rate and sampling number are set, it is known that ground
Signal magnetic field range is 20,000nT~100,000nT, is 850Hz according to the frequency range that FID signal can be obtained in magnetic rotaion comparison formula
~4,300Hz, therefore, in specific embodiment, the sample rate of setting ADC collector is 10kHz, and sampling number is 2048 points, is adopted
Collecting signal time is about 205ms, frequency resolution 10kHz/2048=4.88Hz.Preset time 5ms is waited after the completion of excitation,
Conducive to excluding to interfere caused by circuit oscillation, first FID signal is acquired using the aforementioned ADC set, is generated discrete
Data, and send data to STM32；
S3, space matrix is constructed according to the discrete data using STM32, and uses PCA (principal component analysis) and SVD
(singular value decomposition) algorithm carries out principal component separation and singular value decomposition respectively to the space matrix with cancelling noise, is weighed
Structure data, specifically include:
S31, STM32 drive high-frequency oscillating circuits and direct-flow impulse circuit first time stimulus sensor to generate the first FID letter
After number, it is amplified by amplifying circuit, then it is recorded using ADC collector, obtains discrete data x=
[x1,x2,…,xn], and it is transmitted to STM32；
S32, new space matrix m is constructed using STM32:
S33, in STM32, using PCA algorithm to space matrix m carry out principal component analysis, by purified signal and noise
Signal is separated, to obtain new discrete data x '=[x1’,x2’,…,xn']；
S34, new space matrix Σ is constructed using STM32:
S35, in STM32, use svd algorithm to the space matrix Σ carry out singular value decomposition with it is further rejecting make an uproar
Sound obtains reconstruct data；
S4, in STM32, using data are reconstructed described in FFT (fast Fourier transform) algorithm process, obtain described first
The corresponding first frequency value of maximum peak voltage in FID signal frequency spectrum；
S5, in STM32, the inductance value of the sensor and the first frequency value are substituted into LC resonance equations the
One capacitance, and described the is switched to by zero using STM32 driving and the capacitance in the tuning circuit of the sensor parallel
One capacitance.LC resonance formula is as follows:
In formula, f0, L and C be respectively frequency variable, inductance variable and capacitor variable；
S6, high-frequency oscillating circuits and direct-flow impulse circuit are driven using STM32, again stimulus sensor 100ms output the
Two FID signals wait preset time 5ms after the completion of excitation, and transmit a signal to tuning circuit, transmit signal after tuned
To amplifying circuit, the signal after shaping is passed signal progress shaping by the amplified hysteresis comparator circuit that transmits a signal to
Transport to FPGA；The second frequency value of second FID signal is obtained using FPGA；By the inductance value of the sensor and described
Two frequency values substitute into the second capacitance of LC resonance equations, and utilize the tuning electricity of STM32 driving and the sensor parallel
Capacitance in road is switched to second capacitance by the first capacitor value；
S7, high-frequency oscillating circuits and direct-flow impulse circuit are driven using STM32, again stimulus sensor 100ms output the
Three FID signals wait preset time 5ms after the completion of excitation, and transmit a signal to tuning circuit, transmit signal after tuned
To amplifying circuit；Narrow-band filtering circuit is driven using STM32, using the second frequency value as its centre frequency to by amplifying
The third FID signal after circuit is filtered, and the filtered third FID signal is transmitted to hysteresis comparator circuit
Shaping is carried out, and the signal after shaping is transmitted to FPGA；The third of the third FID signal after shaping is obtained using FPGA
Frequency values, and the frequency for the FID signal that the third frequency values are detected as the sensor.
The induction FID that the present invention exports rotary proton class sensor using the mode that PCA algorithm is combined with svd algorithm
Signal carries out principal component analysis and singular value decomposition processing respectively, can further suppress unknown noise, improves FID signal noise
Than；By the way of third harmonic tuning, first time actuated sensor exports the first FID signal, passes through PCA algorithm and svd algorithm pair
Signal carries out noise reduction process, and obtains an initial centre frequencies f in conjunction with fft algorithm1；Second of actuated sensor output second
FID signal, measurement FID signal frequency obtain f2, and secondary tune is completed with the centre frequency of this frequency adjustment narrow-band filtering circuit
It is humorous；Third time actuated sensor exports third FID signal, and measurement passes through the FID signal frequency f after narrow-band filtering at this time3, and with
This frequency finally tunes centre frequency as system.
As shown in figure 4, ADC collector is collected to amplify untuned through amplifying circuit when to be followed successively by tuning capacitance be zero
The untreated frequency spectrum of FID signal, this FID signal through existing auto-correlation algorithm (Auto Correlation) treated frequency
The frequency spectrum of spectrum and this FID signal the gained reconstruct data composition after PCA&SVD algorithm process of the present invention；Comparison can be found through this hair
Frequency spectrum after bright PCA&SVD algorithm process is distincter, and signal-to-noise ratio is higher.
To the currently used tuning method based on peak detection method and auto-correlation algorithm and the present invention is based on PCA&SVD algorithms
Third harmonic tuning method be tuned the comparative experiments of precision and speed, with the timer of STM32 to three kinds of tuning algorithm institute's used times
Between carry out timing.According to the design parameter of experiment porch, in same test magnetic field environment: testing location magnetic field is about 49,
323nT, i.e. 2100Hz；Sensor resonant -3dB frequency range: 2072Hz~2128Hz, sensors inductance value 34mH, in conjunction with LC
Resonance equation obtains tuning capacitance capacitance range: 168nF~173nF.As long as the tuning capacitance capacitance that i.e. three kinds of algorithms obtain exists
Within the scope of this, it can illustrate to tune successfully.In glitch-free environment, 5 observation is carried out to three kinds of methods respectively, result is such as
Shown in table 1.
The measurement result of the lower three kinds of methods of the noiseless environment of table 1
As can be seen from Table 1, from the point of view of the speed of tuning, since three kinds of algorithms are sequential programme structure, so program
The execution time is definite value, and the time used in peak detection method is about 5 times of auto-correlation algorithm and PCA&SVD algorithm；From the essence of tuning
From the point of view of degree, the obtained tuning capacitance value of three kinds of algorithms is within the scope of 168nF~173nF, more accurately.It can be said that
Bright, under noiseless environment, the performance of auto-correlation algorithm and PCA&SVD algorithm is suitable.
In the environment of interference, 5 observation is carried out to above-mentioned three kinds of methods respectively, the results are shown in Table 2.
The measurement result of the lower three kinds of methods of 2 interference environment of table
As can be seen from Table 2, when external environment has interference, the tuning precision of peak detection method and auto-correlation algorithm is bright
Aobvious decline, obtained tuning capacitance capacitance can make rotary proton class sensor detuning phenomena occur, reduce the signal-to-noise ratio of signal, from
And to apply has the instrument of rotary proton class sensor can not work normally；And the test result of PCA&SVD algorithm not by
To any influence, tuning precision is high, speed is fast and has repeatability.
In conclusion the present invention, which is used, realizes rotary proton by the method that PCA algorithm, svd algorithm and fft algorithm combine
The tuning of class sensor, effectively overcomes that existing tuning algorithm tuned speed is slow, tuning precision is low under interference environment, easy loses
The defects of adjusting phenomenon；While reducing tuning period, the tuning precision of rotary proton class sensor is improved, it can be achieved that wide measurement
Selection of the range to tuning capacitance improves the signal-to-noise ratio of later period measuring signal, is applied to rotary proton class magnetometer, optical pumping magnetic force
Instrument and nuclear magnetic resonance rotary proton FID signal imager etc. effectively improve instrument by the instrument of rotary proton class sensor
Performance.
The embodiment of the present invention is described with above attached drawing, but the invention is not limited to above-mentioned specific
Embodiment, the above mentioned embodiment is only schematical, rather than restrictive, those skilled in the art
Under the inspiration of the present invention, without breaking away from the scope protected by the purposes and claims of the present invention, it can also make very much
Form, all of these belong to the protection of the present invention.
Claims (10)
1. the system for improving rotary proton class sensor tuning precision and signal-to-noise ratio, which is characterized in that weak including dynamical nuclear polarization
Magnetic Sensor, high-frequency oscillating circuits, direct-flow impulse circuit, tuning circuit, amplifying circuit, narrow-band filtering circuit, sluggishness are more electric
Road, ADC collector, constant-temperature crystal oscillator, FPGA digital Frequency Measuring module and STM32；High-frequency oscillating circuits and direct-flow impulse circuit are common
Form exciting circuit；
Dynamical nuclear polarization sensor receives the pumping signal of high-frequency oscillating circuits and direct-flow impulse circuit, induces FID signal, and
Pass to tuning circuit；After tuning circuit is tuned signal, amplifying circuit is passed to；Amplifying circuit amplifies signal
Afterwards, narrow-band filtering circuit, hysteresis comparator circuit and ADC collector are delivered separately to；Narrow band filter carries out signal
After bandpass filtering, it is transmitted to hysteresis comparator circuit；After hysteresis comparator circuit carries out shaping to signal, FPGA is passed it to
Carry out later period signal processing；ADC collector is connect with STM32, carries out the acquisition and processing of data；STM32 and higher-order of oscillation electricity
Road is connected with direct-flow impulse circuit, controls the open and close of pumping signal；STM32 is connect with FPGA, carries out frequency to FID signal
Rate measurement；STM32 is connected with narrow band filter, adjusts its narrow band center frequency；Constant-temperature crystal oscillator is connected with FPGA.
2. the system according to claim 1 for improving rotary proton class sensor tuning precision and signal-to-noise ratio, feature exist
In STM32 for driving high-frequency oscillating circuits and direct-flow impulse circuit stimulus sensor to export the first FID signal, complete by excitation
After wait preset time, driving ADC collector acquires first FID signal, generates discrete data；According to the discrete data
Space matrix is constructed, and principal component separation and singular value point are carried out to the space matrix using PCA algorithm and svd algorithm respectively
Solution obtains reconstruct data with cancelling noise；The reconstruct data are handled using fft algorithm, obtain the first FID signal frequency spectrum
The corresponding first frequency value of middle maximum peak voltage；The inductance value of the sensor and the first frequency value are substituted into LC resonance
Equations first capacitor value, and tuning circuit is driven to be switched to the capacitance of the tuning capacitance with the sensor parallel by zero
The first capacitor value；
It is also used to that exciting circuit stimulus sensor is driven to export the second FID signal again, waits preset time after the completion of excitation,
Driving FPGA measures the second frequency value of second FID signal；By the inductance value of the sensor and the second frequency value
The second capacitance of LC resonance equations is substituted into, and drives tuning circuit by the capacitance of the tuning capacitance by the first capacitor
Value is switched to second capacitance；
It is also used to that exciting circuit stimulus sensor is driven to export third FID signal again；It is also used to the narrow-band filtering
The centre frequency of circuit is set as the second frequency value；Its 3rd FID letter after being also used to that FPGA is driven to measure shaping
Number third frequency values, and the rate-adaptive pacemaker for the FID signal that the third frequency values are detected as the sensor.
3. the system according to claim 1 for improving rotary proton class sensor tuning precision and signal-to-noise ratio, feature exist
In high-frequency oscillating circuits is used for the stimulus sensor under the driving of STM32 and exports the first FID signal；It is also used to described
Stimulus sensor exports the second FID signal under the driving of STM32；It is also used to the stimulus sensor under the driving of the STM32
Export third FID signal；
Direct-flow impulse circuit is used for the stimulus sensor under the driving of STM32 and exports the first FID signal；It is also used to described
Stimulus sensor exports the second FID signal under the driving of STM32；It is also used to the stimulus sensor under the driving of the STM32
Export third FID signal.
4. the system according to claim 1 for improving rotary proton class sensor tuning precision and signal-to-noise ratio, feature exist
In tuning circuit is for being switched to institute by zero for the capacitance of the tuning capacitance with the sensor parallel under the driving of STM32
State first capacitor value；It is also used to the capacitance of the tuning capacitance under the driving of the STM32 by the first capacitor value
It is switched to second capacitance；It is also used to the capacitance of the tuning capacitance under the driving of the STM32 by described
Two capacitances are switched to the third capacitance.
5. the system according to claim 1 for improving rotary proton class sensor tuning precision and signal-to-noise ratio, feature exist
In the first FID signal is amplified, adopted for the collector for waiting preset time after the completion of motivating by amplifying circuit
Collection；It is also used to wait preset time after the completion of motivating, and the second FID signal is amplified, hysteresis comparator circuit shaping is used for；
It is also used to wait preset time after the completion of motivating, and amplifies to the third FID signal, is used for the narrow-band filtering circuit
Filtering；Narrow-band filtering circuit is used for the frequency centered on second frequency value and is filtered to amplified third FID signal, uses
In hysteresis comparator circuit shaping.
6. the system according to claim 1 for improving rotary proton class sensor tuning precision and signal-to-noise ratio, feature exist
In hysteresis comparator circuit is used to amplified second FID signal carrying out shaping, measures, is also used to filtering for FPGA
The third FID signal afterwards carries out shaping, measures for the FPGA；ADC collector under the driving of STM32 for acquiring
First FID signal generates discrete data.
7. the system according to claim 1 for improving rotary proton class sensor tuning precision and signal-to-noise ratio, feature exist
In FPGA digital Frequency Measuring module is used to measure the second frequency value of the second FID signal under the driving of the STM32, also uses
The third frequency values of third FID signal after measuring shaping.
8. the system according to claim 1 for improving rotary proton class sensor tuning precision and signal-to-noise ratio, feature exist
In constant-temperature crystal oscillator is for generating stable oscillator signal, and the standard technique frequency values as FPGA digital Frequency Measuring module use.
9. the method for improving rotary proton class sensor tuning precision and signal-to-noise ratio is tuned based on rotary proton class sensor is improved
Precision and the system of signal-to-noise ratio are realized characterized by comprising
S1, high-frequency oscillating circuits and direct-flow impulse circuit is driven to motivate dynamical nuclear polarization sensor 400ms, output using STM32
First FID signal, and signal is passed into tuning circuit, tuning circuit passes it to ADC collector after amplifying signal；
It is waited after the completion of S2, the sample rate that ADC collector is set, sampling number, acquisition signal time, frequency resolution and excitation
Preset time acquires first FID signal using the ADC set, generates discrete data, and send data to STM32；
S3, space matrix is constructed according to the discrete data using STM32, and using PCA and svd algorithm to the space matrix
It carries out principal component separation and singular value decomposition respectively with cancelling noise, obtains reconstruct data；
S4, in STM32, the reconstruct data are handled using fft algorithm, obtain maximum peak in the first FID signal frequency spectrum
The corresponding first frequency value of threshold voltage；
S5, in STM32, the inductance value of the sensor and the first frequency value are substituted into the first electricity of LC resonance equations
Capacitance, and first electricity is switched to by zero with the capacitance in the tuning circuit of the sensor parallel using STM32 driving
Capacitance；
S6, high-frequency oscillating circuits and direct-flow impulse circuit are driven using STM32, stimulus sensor 100ms exports the 2nd FID again
Signal waits preset time after the completion of excitation, and transmits a signal to tuning circuit, and amplification electricity is transmitted a signal to after tuned
Signal after shaping is transmitted to FPGA to signal progress shaping by road, the amplified hysteresis comparator circuit that transmits a signal to；
The second frequency value of second FID signal is obtained using FPGA；By the inductance value of the sensor and the second frequency value
The second capacitance of LC resonance equations is substituted into, and utilizes STM32 driving and the electricity in the tuning circuit of the sensor parallel
Capacitance is switched to second capacitance by the first capacitor value；
S7, high-frequency oscillating circuits and direct-flow impulse circuit are driven using STM32, stimulus sensor 100ms exports the 3rd FID again
Signal waits preset time after the completion of excitation, and transmits a signal to tuning circuit, and amplification electricity is transmitted a signal to after tuned
Road；Narrow-band filtering circuit is driven using STM32, using the second frequency value as its centre frequency to after amplifying circuit
The third FID signal is filtered, and by the filtered third FID signal be transmitted to hysteresis comparator circuit carry out it is whole
Shape, and the signal after shaping is transmitted to FPGA；The third frequency of the third FID signal after shaping is obtained using FPGA
Value, and the frequency for the FID signal that the third frequency values are detected as the sensor.
10. the method according to claim 9 for improving rotary proton class sensor tuning precision and signal-to-noise ratio, feature exist
In step S3 is specifically included:
After S31, STM32 drive high-frequency oscillating circuits and direct-flow impulse circuit first time stimulus sensor to generate the first FID signal,
It is amplified by amplifying circuit, then it is recorded using ADC collector, obtains discrete data x=[x1,
x2,…,xn], and it is transmitted to STM32；
S32, new space matrix m is constructed using STM32:
S33, in STM32, using PCA algorithm to space matrix m carry out principal component analysis, by purified signal and noise signal
It is separated, to obtain new discrete data x '=[x1’,x2’,…,xn']；
S34, new space matrix Σ is constructed using STM32:
S35, in STM32, use svd algorithm to carry out singular value decomposition to the space matrix Σ with further cancelling noise,
Obtain reconstruct data.
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