CN106383367B - Absolute gravity measurement method and apparatus - Google Patents
Absolute gravity measurement method and apparatus Download PDFInfo
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- CN106383367B CN106383367B CN201510462931.8A CN201510462931A CN106383367B CN 106383367 B CN106383367 B CN 106383367B CN 201510462931 A CN201510462931 A CN 201510462931A CN 106383367 B CN106383367 B CN 106383367B
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Abstract
The invention discloses a kind of absolute gravity measurement method and apparatus, wherein absolute gravity measurement method includes：The fall time t of the tested falling bodies of time collecting unit detection, and t is sent to host computer；Optical interdferometer detection is tested whereabouts displacement signal d of the falling bodies relative to reference prism1(t), and by signal d1(t) it is sent to host computer；Vibration measuring unit detects displacement signal d of the reference prism with ground vibration2(t), and by signal d2(t) it is sent to host computer；Host computer utilizes signal d2(t) to signal d1(t) it compensates, obtains displacement signal d (t) of the tested falling bodies relative to ground；Host computer obtains gravity acceleration g according to signal d (t) and t.For the present invention by ground vibration signal compensation to tested falling bodies whereabouts displacement, the measurement for being tested falling bodies displacement is more accurate, can substantially reduce pendulous frequency, obtain more accurate acceleration of gravity.
Description
Technical field
The present invention relates to gravity measurement field more particularly to a kind of absolute gravity measurement method and apparatus.
Background technology
The principle of current optical interference absolute gravimeter is accurately to measure tested falling bodies in high vacuum conditions in gravity
The time and displacement that free-falling is undergone in, then according to formula (1)：
S (t)=s0+v0t+1/2gt2 (1)
G is calculated, wherein t is the fall time of tested falling bodies, and s (t) is tested displacement of the falling bodies relative to ground for t moment,
s0To be tested the initial displacement of falling bodies, v0To be tested the initial velocity of falling bodies.The original of the tested falling bodies displacement of principle of optical interference detection
Reason is as shown in Figure 1.The laser beam of optical interdferometer is sent out from laser 101, is passed through spectroscope (Beam Splitter)
102 points are two beams, and a branch of of reflection is measuring beam (dotted line expression), and a branch of of transmission is reference beam (solid line expression).It surveys
Amount light beam is irradiated to tested falling bodies 103 (tested falling bodies 103 are rectangular three-dimensional prism, are placed in vacuum chamber) and reflects, through dividing
Light microscopic 102 is irradiated to reference prism 104, and reflexes to spectroscope 102 through reference prism 104, converges with reference beam and is irradiated to
On photodetector 105.When tested 103 freely falling body of falling bodies, the reference beam hair of reflected measuring beam and transmission
Raw interference, generates interference fringe.Photodetector 105 turns tested falling bodies 103 in the fall time t interference fringe numbers generated
Electric signal is changed to, the wherein number of interference fringe corresponds to the whereabouts displacement of tested falling bodies 103, and the time set of absolute gravimeter is same
The time that Shi Jilu falls.It in the case of ignoring the variation of gravity acceleration g spatially, utilizes formula (1), you can obtain weight
The numerical value of power acceleration g.
However in practical operation, due to Earth Surface vibration etc., reference prism 104 also can relative to earth center
Generate displacement, this allow for the tested falling bodies 103 measured relative to reference prism 104 displacement and tested falling bodies 103 relative to
Occurs deviation between the actual displacement of earth center, therefore the numerical value of obtained gravity acceleration g is also not accurate enough.
Being accurately positioned in the prior art by mechanical structure can be by the horizontal swing-scanning control of tested falling bodies in allowed band
The displacement of vertical direction interior, however that reference prism can not be avoided to be generated with ground vibration.Fig. 2 is that the principle of vibration compensation method is shown
It is intended to.As shown in Fig. 2, that optical interdferometer measures is displacement d of the tested falling bodies 103 relative to reference prism 1041, and it is practical
In measurement, reference prism 104 can also generate displacement d with ground vibration2.Due to reference prism 104 as ground vibration causes to do
The practical whereabouts displacement of tested falling bodies that interferometer is surveyed is inaccurate, final gravity acceleration value is caused to measure inaccurate, existing skill
A kind of method is to need to take multiple measurements in art, and the method that results are averaged eliminates shadow of the single measurement to accuracy
It rings.Since this method needs to rely on a large amount of experiment number, and (A classes are not true in meterological for the dispersibility of multiple measurement results
It is fixed to spend to weigh) it is bigger, effect is not ideal enough.Another improved method is using low frequency vibration-measuring sensor, measures reference
Then prism is compensated relative to the displacement on ground.However, as shown in figure 3, low frequency vibration-measuring sensor is to difference in this method
The vibration of frequency, different directions again with different frequency responses, there are attenuation and phase drift so that vibration measurement not
It is enough accurate.
Invention content
The present invention provides a kind of absolute gravity measurement method and apparatus, will be under ground vibration signal compensation to tested falling bodies
On dropping place is moved, the measurement for being tested falling bodies displacement is more accurate, and then can more accurately measure acceleration of gravity.
According to an aspect of the invention, there is provided a kind of absolute gravity measurement method, including：
The fall time t of the tested falling bodies of time collecting unit detection, and t is sent to host computer；
Optical interdferometer detection is tested whereabouts displacement signal d of the falling bodies relative to reference prism1(t), and by signal d1(t)
It is sent to host computer；
Vibration measuring unit detects displacement signal d of the reference prism with ground vibration2(t), and by signal d2(t) it is sent to upper
Machine；
Host computer utilizes signal d2(t) to signal d1(t) it compensates, obtains tested falling bodies and believe relative to the displacement on ground
Number d (t)；
Host computer obtains gravity acceleration g according to signal d (t) and t.
In one embodiment, host computer utilizes signal d2(t) to signal d1(t) it compensates, it is opposite to obtain tested falling bodies
Include in the step of displacement signal d (t) on ground：
It is tested using test signal, obtains amplitude versus frequency characte H of the transfer function H (f) in frequency point k of vibration measuring unitk(f)
With phase-frequency characteristic Φk(f), wherein 1≤k≤n, n are the frequency point number for needing to test；
According to Hk(f) and Φk(f) to signal d2(t) inverting is carried out, obtains inverting signal d2’(t)；
Utilize inverting signal d2' (t) to signal d1(t) it compensates, obtains displacement signal of the tested falling bodies relative to ground
d(t)。
In one embodiment, it is tested using test signal, obtains the transfer function H (f) of vibration measuring unit in frequency point k
Amplitude versus frequency characte Hk(f) and phase-frequency characteristic Φk(f) the step of, includes：
By test signal x (t) and corresponding output signal y (t), and by x (t) and y (t) be transformed to frequency domain signal X (f) and
Y(f)；
Amplitude versus frequency characte H of the transfer function H (f) in frequency point k of vibration measuring unit is obtained according to X (f) and Y (f)k(f) and phase frequency
Characteristic Φk(f), wherein, H (f)=Y (f)/X (f).
In one embodiment, according to Hk(f) and Φk(f) to signal d2(t) inverting is carried out, obtains inverting signal d2’(t)
The step of include：
To signal d2(t) digital collection is carried out；
By the signal d after digital collection2(t) the first window function is multiplied by, and is transformed to frequency-region signal D2(f)；
On each frequency point k, by signal D2(f) range value divided by Hk(f), phase value subtracts Φk(f), after obtaining amendment
Frequency-region signal D2’(f)；
By signal D2' (f) be multiplied by the second window function；
The signal D of the second window function will be multiplied by2' (f) is transformed to time-domain signal, and carries out waveform concatenation and base wavelet,
Obtain inverting signal d2’(t)。
In one embodiment, the first window function and the second window function are Hanning window function.
According to another aspect of the present invention, a kind of absolute gravity measurement device is provided, including：Time collecting unit, light
Interferometer, vibration measuring unit and host computer are learned, wherein：
T for detecting the fall time t of tested falling bodies, and is sent to host computer by time collecting unit；
Optical interdferometer, for detecting whereabouts displacement signal d of the tested falling bodies relative to reference prism1(t), and by signal
d1(t) it is sent to host computer；
Vibration measuring unit, for detecting displacement signal d of the reference prism with ground vibration2(t), and by signal d2(t) it is sent to
Host computer；
Host computer, for utilizing signal d2(t) to signal d1(t) it compensates, obtains position of the tested falling bodies relative to ground
Shifting signal d (t)；Gravity acceleration g is obtained according to signal d (t) and t.
In one embodiment, host computer specifically includes test module, inverting module and compensation calculation module, wherein：
Test module for being tested using test signal, obtains the transfer function H (f) of vibration measuring unit frequency point k's
Amplitude versus frequency characte Hk(f) and phase-frequency characteristic Φk(f), wherein 1≤k≤n, n are the frequency point number for needing to test；
Inverting module, for according to Hk(f) and Φk(f) to signal d2(t) inverting is carried out, obtains inverting signal d2’(t)；
Compensation calculation module, for utilizing inverting signal d2' (t) to signal d1(t) it compensates, obtains tested falling bodies phase
For the displacement signal d (t) on ground；Gravity acceleration g is obtained according to signal d (t) and t.
In one embodiment, test module is specifically used for converting test signal x (t) and corresponding output signal y (t)
For frequency domain signal X (f) and Y (f)；It is special that amplitude-frequency of the transfer function H (f) of vibration measuring unit in frequency point k is obtained according to X (f) and Y (f)
Property Hk(f) and phase-frequency characteristic Φk(f), wherein, H (f)=Y (f)/X (f).
In one embodiment, inverting module is specifically used for signal d2(t) digital collection is carried out；By the letter after digital collection
Number d2(t) the first window function is multiplied by, and is transformed to frequency-region signal D2(f)；On each frequency point k, by signal D2(f) range value
Divided by Hk(f), phase value subtracts Φk(f), revised frequency-region signal D is obtained2’(f)；By signal D2' (f) be multiplied by the second window letter
Number；The signal D of the second window function will be multiplied by2' (f) is transformed to time-domain signal, and carries out waveform concatenation and base wavelet, it obtains anti-
Drill signal d2’(t)。
In one embodiment, the first window function and the second window function are Hanning window function.
The present invention provides a kind of absolute gravity measurement method and apparatus, will be under ground vibration signal compensation to tested falling bodies
On dropping place is moved, so that the whereabouts displacement measured can be substantially reduced closer to the whereabouts displacement of practical tested falling bodies
Pendulous frequency obtains more accurate acceleration of gravity.
Description of the drawings
It to describe the technical solutions in the embodiments of the present invention more clearly, below will be to required in embodiment or description
The attached drawing used is briefly described, it should be apparent that, the accompanying drawings in the following description is only some embodiments of the present invention, right
For those of ordinary skill in the art, without having to pay creative labor, it can also be obtained according to these attached drawings
Other attached drawings.
Fig. 1 is the schematic diagram of optical interference testing principle.
Fig. 2 is the principle schematic of vibration compensation method.
Fig. 3 is the frequency response characteristic schematic diagram in one direction of low frequency vibration-measuring sensor.
Fig. 4 is the schematic diagram of one embodiment of absolute gravity measurement method of the present invention.
Fig. 5 is the schematic diagram of another embodiment of absolute gravity measurement method of the present invention.
Fig. 6 is the method schematic diagram that vibration measuring unit transmission function Frequency Response is tested in the present invention.
Fig. 7 is the method schematic diagram for carrying out inverting in the present invention to signal.
Fig. 8 is the schematic diagram of one embodiment of absolute gravity measurement device of the present invention.
Fig. 9 is the schematic diagram of absolute gravity measurement device host computer one embodiment of the present invention.
Specific embodiment
Below in conjunction with the attached drawing in the embodiment of the present invention, the technical solution in the embodiment of the present invention is carried out clear, complete
Site preparation describes, it is clear that described embodiment is only part of the embodiment of the present invention, instead of all the embodiments.Below
Description only actually at least one exemplary embodiment is illustrative, is never used as to the present invention and its application or makes
Any restrictions.Based on the embodiments of the present invention, those of ordinary skill in the art are not making creative work premise
Lower all other embodiments obtained, shall fall within the protection scope of the present invention.
Unless specifically stated otherwise, the component and positioned opposite, the digital table of step otherwise illustrated in these embodiments
It is not limited the scope of the invention up to formula and numerical value.
Fig. 4 is the schematic diagram of one embodiment of absolute gravity measurement method of the present invention.Preferably, the method for the present embodiment
Step can be performed by the absolute gravity measurement device of the present invention, including：
Step 401, the fall time t of the tested falling bodies of time collecting unit detection1, and by t1It is sent to host computer.
Preferably, time collecting unit uses high-precision rubidium clock, to improve the precision of time measurement.And using synchronous triggering
Signal ensures the synchro measure of optical interdferometer and vibration measuring unit.
Step 402, optical interdferometer detection is tested whereabouts displacement signal d of the falling bodies relative to reference prism1It (t), and will
Signal d1(t) it is sent to host computer.
Preferably, optical interdferometer is Michelson laser interferometer.
Step 403, vibration measuring unit detects displacement signal d of the reference prism with ground vibration2(t), and by signal d2(t) it sends out
Give host computer.
Step 404, host computer utilizes signal d2(t) to signal d1(t) it compensates, obtains tested falling bodies relative to ground
Displacement signal d (t).
For example, host computer according to reference prism with the displacement signal d of ground vibration2(t) to tested falling bodies relative to reference
The whereabouts displacement signal d of prism1(t) it compensates, obtains displacement signal d (t) of the tested falling bodies relative to ground.When with reference to rib
Mirror with ground vibration displacement signal d2(t) with tested falling bodies relative to the whereabouts displacement signal d of reference prism1(t) when in the same direction, d
(t)=d1(t)+|d2(t)|；When reversed, d (t)=d1(t)-|d2(t)|。
Step 405, host computer obtains gravity acceleration g according to signal d (t) and t.
For example, host computer chooses three time point t respectively on signal d (t) and t1, t2And t3, corresponding three displacement point d
(t1), d (t2) and d (t3), term coefficient twice is obtained using least square fitting according to formula (1), it is that gravity adds to be multiplied by 2
Speed g1.Test of repeatedly falling is carried out, by taking n times are tested as an example, obtains acceleration gi, wherein 1≤i≤N, is averaged n times result
Value, you can obtain the value of gravity acceleration g.Those skilled in the art are it will be appreciated that can be according to required precision and experiment
Situation, determine choose time point number and measure number and how using least square fitting obtain gravity accelerate
Spend g.
The absolute gravity measurement method of the present invention, by reference prism under the bit shift compensation to tested falling bodies of ground vibration
On dropping place is moved, so that the whereabouts displacement measured can be substantially reduced closer to the whereabouts displacement of practical tested falling bodies
Pendulous frequency obtains more accurate acceleration of gravity.
Fig. 5 is the schematic diagram of one embodiment of absolute gravity measurement method of the present invention.Preferably, the method for the present embodiment
Step can be performed by the absolute gravity measurement device of the present invention, including：
Step 501, the fall time t of the tested falling bodies of time collecting unit detection, and t is sent to host computer.
Preferably, the fall time t of tested falling bodies is detected using high-precision rubidium clock, to improve the precision of time measurement.
Step 502, optical interdferometer detection is tested whereabouts displacement signal d of the falling bodies relative to reference prism1It (t), and will
Signal d1(t) it is sent to host computer.
Step 503, vibration measuring unit detects displacement signal d of the reference prism with ground vibration2(t) and it is sent to host computer.
Step 504, host computer is tested using test signal, obtains the transfer function H (f) of vibration measuring unit in frequency point k
Amplitude versus frequency characte Hk(f) and phase-frequency characteristic Φk(f), wherein 1≤k≤n, n are the frequency point number for needing to test.
Preferably, according to the range of ground vibration, n frequency point is chosen in transfer function H (f), obtains H (f) in each frequency point
Amplitude versus frequency characte Hk(f) and phase-frequency characteristic Φk(f) it and preserves, for use in signal d2(t) inverting.
Step 505, host computer is according to Hk(f) and Φk(f) to signal d2(t) inverting is carried out, obtains inverting signal d2’(t)。
Carry out the inverting signal d obtained after inverting2' (t) more accurate.
Step 506, host computer utilizes inverting signal d2' (t) to signal d1(t) compensate, obtain tested falling bodies relative to
The displacement signal d (t) on ground.
For example, host computer is according to inverting signal d2' (t) to be tested falling bodies relative to reference prism whereabouts displacement signal d1
(t) it compensates, obtains displacement signal d (t) of the tested falling bodies relative to ground.As inverting signal d2' (t) and tested falling bodies phase
For the whereabouts displacement signal d of reference prism1(t) when in the same direction, d (t)=d1(t)+|d2’(t)|；When reversed, d (t)=d1(t)-
|d2’(t)|。
Step 507, host computer obtains gravity acceleration g according to signal d (t) and t.
For example, host computer chooses three time point t respectively on signal d (t) and t1, t2And t3, corresponding three displacement point d
(t1), d (t2) and d (t3), term coefficient twice is obtained using least square fitting according to formula (1), it is that gravity adds to be multiplied by 2
Speed g1.Test of repeatedly falling is carried out, by taking n times are tested as an example, obtains acceleration gi, wherein 1≤i≤N, is averaged n times result
Value, you can obtain the value of gravity acceleration g.Those skilled in the art are it will be appreciated that can be according to required precision and experiment
Situation, determine choose time point number and measure number and how using least square fitting obtain gravity accelerate
Spend g.
The absolute gravity measurement method of the present invention, by signal d2(t) inverting, to the amplitude and phase in frequency domain of signal
Position is modified, and obtains more accurate inverting signal d2' (t), so that the whereabouts displacement measured is closer to practical
The whereabouts displacement of tested falling bodies, can substantially reduce pendulous frequency, obtain more accurate acceleration of gravity.
Fig. 6 is the side that transmission function Frequency Response is tested in one embodiment of the absolute gravity measurement method of the present invention
The schematic diagram of method, as shown in fig. 6, including：
Step 601, test signal x (t) and corresponding output signal y (t) are transformed to frequency domain signal X (f) and Y (f).
Preferably, the methods of Fourier transformation, Fast Fourier Transform (FFT), Laplace transform may be used is by time-domain signal
X (t) and y (t) are transformed to frequency domain signal X (f) and Y (f).
Step 602, amplitude versus frequency characte H of the transfer function H (f) in frequency point k of vibration measuring unit is obtained according to X (f) and Y (f)k
(f) and phase-frequency characteristic Φk(f), wherein, H (f)=Y (f)/X (f).
Preferably, according to the frequency characteristic of ground vibration and required precision, the frequency of frequency points n and each frequency point k is chosen
Rate value.After those skilled in the art are it will be appreciated that obtain the transfer function H (f) of vibration measuring unit, can further it obtain
The amplitude versus frequency characte H of frequency point kk(f) and phase-frequency characteristic Φk(f)。
Fig. 7 is in one embodiment of the absolute gravity measurement method of the present invention, to the schematic diagram of signal inversion method.It is excellent
Choosing, the method for the present embodiment is carried out by host computer in the present invention, including：
Step 701, to signal d2' (t) progress digital collection.
Step 702, by the signal d after digital collection2(t) the first window function is multiplied by, and is transformed to frequency-region signal D2(f).Its
In, by signal d2(t) it is transformed to frequency-region signal D2(f) Fourier transformation, Fast Fourier Transform (FFT), Laplce's change may be used
The methods of changing.
Preferably, the first window function is Hanning window function.
Step 703, on each frequency point k, by signal D2(f) range value divided by Hk(f), phase value subtracts Φk(f), it obtains
To revised frequency-region signal D2’(f).By to signal D2(f) it is modified, amplitude and phase is compensated, so as to get
Signal D2' planarization of (f) signal, frequency range is wider, measurement accuracy higher.
Step 704, by signal D2' (f) be multiplied by the second window function.
Step 705, the signal D that the second window function will be multiplied by2' (f) is transformed to time-domain signal, and carries out waveform concatenation and base
Line amendment obtains inverting signal d2’(t)。
Preferably, the second window function is Hanning window function.By the amendment of step 703-704, inverting that step 705 obtains
Signal d2' (t) more accurate.Wherein, by frequency-region signal D2' (f) be transformed to signal d2' (t) may be used inverse Fourier transform,
The methods of inverse fast Fourier transform, inverse Laplace transformation.
The absolute gravity measurement method of the present invention, can be by reference prism relative to the displacement on ground by the inverting of signal
In real-time compensation to the whereabouts displacement of tested falling bodies, obtained tested falling bodies are more accurate relative to the displacement on ground, effectively subtract
Few experiment number, the numerical value of the gravity acceleration g of fitting are also more accurate.
Fig. 8 is the schematic diagram of one embodiment of the absolute gravity measurement device of the present invention.As shown in figure 8, including：Time
Collecting unit 801, optical interdferometer 802, vibration measuring unit 803 and host computer 804, wherein：
Time collecting unit 801 is used to detect the fall time t of tested falling bodies, and t is sent to host computer 804.
Preferably, time collecting unit 801 is high-precision rubidium clock, to improve the precision of time measurement.
Optical interdferometer 802 is used to detect whereabouts displacement signal d of the tested falling bodies relative to reference prism1It (t), and will letter
Number d1(t) it is sent to host computer 804.
Preferably, optical interdferometer 802 is Michelson laser interferometer.
Vibration measuring unit 803 is used to detect displacement signal d of the reference prism with ground vibration2(t), and by signal d2(t) it sends
To host computer 804.
Preferably, vibration measuring unit 803 is low frequency vibration measuring unit.
Preferably, optical interdferometer 802 and vibration measuring unit 803 are triggered by synchronous triggering signal and measured, ensure to measure when
Between it is synchronous.
Host computer 804 is used to utilize signal d2(t) to signal d1(t) it compensates, obtains tested falling bodies relative to ground
Displacement signal d (t), and gravity acceleration g is obtained according to signal d (t) and t.
For example, in one embodiment, host computer 804 is according to reference prism with the displacement signal d of ground vibration2(t) it is right
It is tested whereabouts displacement signal d of the falling bodies relative to reference prism1(t) it compensates, obtains position of the tested falling bodies relative to ground
Shifting signal d (t).When reference prism is with the displacement signal d of ground vibration2(t) with tested falling bodies relative to the whereabouts of reference prism
Displacement signal d1(t) when in the same direction, d (t)=d1(t)+|d2(t)|；When reversed, d (t1)=d1(t)-|d2(t)|.Host computer 804 exists
Three time point t are chosen respectively on signal d (t) and t1, t2And t3, corresponding three displacement point d (t1), d (t2) and d (t3), according to
Formula (1) obtains term coefficient twice using least square fitting, and it is gravity acceleration g to be multiplied by 21.Repeatedly fall and survey
Examination, by taking n times are tested as an example, obtains acceleration gi, wherein 1≤i≤N, to n times, results are averaged, you can obtains gravity acceleration
Spend the value of g.Those skilled in the art are it will be appreciated that according to required precision and experimental conditions can be determined the time chosen
Point number and the number measured and how using least square fitting to obtain gravity acceleration g.
The absolute gravity measurement device of the present invention, by reference prism with respect under the vibration displacement compensation to tested falling bodies on ground
On dropping place is moved, so that the whereabouts displacement measured can be substantially reduced closer to the whereabouts displacement of practical tested falling bodies
Pendulous frequency obtains more accurate acceleration of gravity.
Fig. 9 is the exemplary plot of one embodiment of host computer 804 in absolute gravity measurement device of the invention.Such as Fig. 9 institutes
Showing, host computer 804 includes test module 8041, inverting module 8042 and compensation calculation module 8043, wherein：
For being tested using test signal, the transfer function H (f) for obtaining vibration measuring unit 803 exists test module 8041
The amplitude versus frequency characte H of frequency point kk(f) and phase-frequency characteristic Φk(f), wherein 1≤k≤n, n are the frequency point number for needing to test.
Preferably, test signal x (t) and corresponding output signal y (t) are transformed to frequency domain signal X by test module 8041
(f) and Y (f)；Amplitude versus frequency characte H of the transfer function H (f) in frequency point k of vibration measuring unit 803 is obtained according to X (f) and Y (f)k(f) and
Phase-frequency characteristic Φk(f), wherein, H (f)=Y (f)/X (f).
Inverting module 8042 is used for according to Hk(f) and Φk(f) to signal d2(t) inverting is carried out, obtains inverting signal d2’
(t)。
Preferably, inverting module 8042 is to signal d2(t) digital collection is carried out；By the signal d after digital collection2(t) it is multiplied by
First window function, and it is transformed to frequency-region signal D2(f)；On each frequency point k, by signal D2(f) range value divided by Hk(f), phase
Place value subtracts Φk(f), revised frequency-region signal D is obtained2’(f)；By signal D2' (f) be multiplied by the second window function；Will be multiplied by
The signal D of two window functions2' (f) is transformed to time-domain signal, and carries out waveform concatenation and base wavelet, obtain inverting signal d2’
(t)。
In one embodiment, the first window function and the second window function are Hanning window function.
Compensation calculation module 8043 is used to utilize inverting signal d2' (t) to signal d1(t) it compensates, obtains tested falling bodies
Relative to the displacement signal d (t) on ground；Gravity acceleration g is obtained according to signal d (t) and t.
For example, in one embodiment, as inverting signal d2' (t) and tested falling bodies relative to reference prism lower dropping place
Shifting signal d1(t) when in the same direction, d (t)=d1(t)+|d2’(t)|；When reversed, d (t)=d1(t)-|d2’(t)|.In signal d (t) and
Three time point t are chosen on t respectively1, t2And t3, corresponding three displacement point d (t1), d (t2) and d (t3), it is utilized according to formula (1)
Least square fitting obtains term coefficient twice, and it is gravity acceleration g to be multiplied by 21.Test of repeatedly falling is carried out, is tested with n times
For, obtain acceleration gi, wherein 1≤i≤N, to n times, results are averaged, you can obtains the value of gravity acceleration g.Ability
Field technique personnel are it will be appreciated that the time point number chosen and measurement can be determined according to required precision and experimental conditions
Number and how using least square fitting to obtain gravity acceleration g.
The absolute gravity measurement method of the present invention, by signal d2(t) inverting, to the amplitude and phase in frequency domain of signal
Position is modified, and obtains more accurate inverting signal d2' (t), so that the whereabouts displacement measured is closer to practical
The whereabouts displacement of tested falling bodies, can substantially reduce pendulous frequency, obtain more accurate acceleration of gravity.
With reference to Fig. 5-Fig. 9, the absolute gravity measurement method and apparatus of the present invention are illustrated.
Time collecting unit 801 carries out timing, and ensure optical interference using synchronous triggering signal using high-precision rubidium clock
803 synchro measure of instrument 802 and vibration measuring unit.When tested falling bodies do the movement of falling object in vacuum chamber, optical interdferometer 802
Detection is tested whereabouts displacement signal d of the falling bodies relative to reference prism1(t), and by signal d1(t) it is sent to host computer 804.It surveys
The unit 803 that shakes detects signal d of the reference prism with the displacement of ground vibration2(t) and it is sent to host computer 804.
The test module 8041 of host computer 804 tests vibration measuring unit 803.Test signal x (t) is inputted into vibration measuring list
Member 803, obtains corresponding output signal y (t), and using Fast Fourier Transform (FFT) method, time-domain signal x (t) and y (t) is converted
For frequency domain signal X (f) and Y (f), and then obtain the transfer function H (f) of vibration measuring unit 803.According to the frequency range of ground vibration
With measuring accuracy requirement, n frequency point is chosen, obtains the amplitude versus frequency characte H of each frequency point kk(f) and phase-frequency characteristic Φk(f), wherein 1
≤k≤n.By Hk(f) and Φk(f) it preserves, to be used for signal inverting later.
Inverting module 8042 is to signal d2(t) the first window function (for example, Hanning window function) is multiplied by after carrying out digital collection,
And Fast Fourier Transform (FFT) is used as frequency-region signal D2(f).On each frequency point k, inverting module 8042 is by signal D2(f) width
Angle value divided by Hk(f), phase value subtracts Φk(f), and then revised frequency-region signal D is obtained2' (f), by signal D2' (f) be multiplied by
Second window function (such as Hanning window function) carries out inverse fast Fourier transform afterwards, and the time domain waveform obtained after transformation is carried out nothing
Seam splicing and base wavelet, obtain inverting signal d2’(t)。
Compensation calculation module 8043 utilizes inverting signal d2' (t) to signal d1(t) it compensates, it is opposite to obtain tested falling bodies
Displacement signal d (t) in ground；For example, three time point t are chosen respectively on signal d (t) and t1, t2And t3, it is three corresponding
Displacement point d (t1), d (t2) and d (t3), term coefficient twice is obtained using least square fitting according to formula (1), being multiplied by 2 is
Gravity acceleration g1.Test of repeatedly falling is carried out, by taking n times are tested as an example, obtains acceleration gi, wherein 1≤i≤N, to n times result
It is averaged, you can obtain the value of gravity acceleration g.Those skilled in the art are it will be appreciated that can be according to required precision
And experimental conditions, it determines the time point number chosen and the number measured and how to be obtained again using least square fitting
Power acceleration g.
The absolute gravity measurement method and apparatus of the present invention, can be by reference prism relative to ground by the inverting of signal
Displacement real-time compensation to the whereabouts displacement of tested falling bodies in so that the whereabouts displacement measured is closer to practical tested
The whereabouts displacement of falling bodies, can substantially reduce pendulous frequency, obtain more accurate acceleration of gravity.
One of ordinary skill in the art will appreciate that hardware can be passed through by realizing all or part of step of above-described embodiment
It completes, relevant hardware can also be instructed to complete by program, the program can be stored in a kind of computer-readable
In storage medium, storage medium mentioned above can be read-only memory, disk or CD etc..
Description of the invention provides for the sake of example and description, and is not exhaustively or will be of the invention
It is limited to disclosed form.Many modifications and variations are obvious for the ordinary skill in the art.It selects and retouches
It states embodiment and is to more preferably illustrate the principle of the present invention and practical application, and those of ordinary skill in the art is enable to manage
The solution present invention is so as to design the various embodiments with various modifications suitable for special-purpose.
Claims (8)
- A kind of 1. absolute gravity measurement method, which is characterized in that including：The fall time t of the tested falling bodies of time collecting unit detection, and t is sent to host computer；Optical interdferometer detection is tested whereabouts displacement signal d of the falling bodies relative to reference prism1(t), and by signal d1(t) it sends To host computer；Vibration measuring unit detects displacement signal d of the reference prism with ground vibration2(t), and by signal d2(t) it is sent to host computer；Host computer utilizes signal d2(t) to signal d1(t) it compensates, obtains displacement signal d of the tested falling bodies relative to ground (t)；Host computer obtains gravity acceleration g according to signal d (t) and t；Wherein, host computer utilizes signal d2(t) to signal d1(t) it compensates, obtains tested falling bodies and believe relative to the displacement on ground The step of number d (t), includes：It is tested using test signal, obtains amplitude versus frequency characte H of the transfer function H (f) in frequency point k of vibration measuring unitk(f) and phase Frequency characteristic Φk(f), wherein 1≤k≤n, n are the frequency point number for needing to test；According to Hk(f) and Φk(f) to signal d2(t) inverting is carried out, obtains inverting signal d2’(t)；Utilize inverting signal d2' (t) to signal d1(t) it compensates, obtains displacement signal d of the tested falling bodies relative to ground (t)。
- 2. according to the method described in claim 1, it is characterized in that, tested using test signal, vibration measuring unit is obtained Transfer function H (f) is in the amplitude versus frequency characte H of frequency point kk(f) and phase-frequency characteristic Φk(f) the step of, includes：Test signal x (t) and corresponding output signal y (t) are transformed to frequency domain signal X (f) and Y (f)；Amplitude versus frequency characte H of the transfer function H (f) in frequency point k of vibration measuring unit is obtained according to X (f) and Y (f)k(f) and phase-frequency characteristic Φk(f), wherein, H (f)=Y (f)/X (f).
- 3. according to the method described in claim 1, it is characterized in that, according to Hk(f) and Φk(f) to signal d2(t) inverting is carried out, Obtain inverting signal d2' (t) the step of include：To signal d2(t) digital collection is carried out；By the signal d after digital collection2(t) the first window function is multiplied by, and is transformed to frequency-region signal D2(f)；On each frequency point k, by signal D2(f) range value divided by Hk(f), phase value subtracts Φk(f), revised frequency is obtained Domain signal D2’(f)；By signal D2' (f) be multiplied by the second window function；The signal D of the second window function will be multiplied by2' (f) is transformed to time-domain signal, and carries out waveform concatenation and base wavelet, it obtains anti- Drill signal d2’(t)。
- 4. according to the method described in claim 3, it is characterized in that, the first window function and the second window function are Hanning window function.
- 5. a kind of absolute gravity measurement device, which is characterized in that including：Time collecting unit, optical interdferometer, vibration measuring unit and Host computer, wherein：T for detecting the fall time t of tested falling bodies, and is sent to host computer by time collecting unit；Optical interdferometer, for detecting whereabouts displacement signal d of the tested falling bodies relative to reference prism1(t), and by signal d1(t) It is sent to host computer；Vibration measuring unit, for detecting displacement signal d of the reference prism with ground vibration2(t), and by signal d2(t) it is sent to upper Machine；Host computer, for utilizing signal d2(t) to signal d1(t) it compensates, obtains tested falling bodies and believe relative to the displacement on ground Number d (t)；Gravity acceleration g is obtained according to signal d (t) and t；Wherein, host computer includes test module, inverting module and compensation calculation module, wherein：Test module for being tested using test signal, obtains amplitude-frequency of the transfer function H (f) in frequency point k of vibration measuring unit Characteristic Hk(f) and phase-frequency characteristic Φk(f), wherein 1≤k≤n, n are the frequency point number for needing to test；Inverting module, for according to Hk(f) and Φk(f) to signal d2(t) inverting is carried out, obtains inverting signal d2’(t)；Compensation calculation module, for utilizing inverting signal d2' (t) to signal d1(t) compensate, obtain tested falling bodies relative to The displacement signal d (t) on ground；Gravity acceleration g is obtained according to signal d (t) and t.
- 6. device according to claim 5, which is characterized in that test module is specifically for by test signal x (t) and accordingly Output signal y (t) be transformed to frequency domain signal X (f) and Y (f)；The transfer function H of vibration measuring unit is obtained according to X (f) and Y (f) (f) in the amplitude versus frequency characte H of frequency point kk(f) and phase-frequency characteristic Φk(f), wherein, H (f)=Y (f)/X (f).
- 7. device according to claim 5, which is characterized in that inverting module is specifically used for signal d2(t) number is carried out to adopt Collection；By the signal d after digital collection2(t) the first window function is multiplied by, and is transformed to frequency-region signal D2(f)；On each frequency point k, By signal D2(f) range value divided by Hk(f), phase value subtracts Φk(f), revised frequency-region signal D is obtained2’(f)；It will letter Number D2' (f) be multiplied by the second window function；The signal D of the second window function will be multiplied by2' (f) be transformed to time-domain signal, traveling wave of going forward side by side shape is spelled It connects and base wavelet, obtains inverting signal d2’(t)。
- 8. device according to claim 7, which is characterized in that the first window function and the second window function are Hanning window function.
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| CN111413749A (en) * | 2020-04-03 | 2020-07-14 | 自然资源部第二海洋研究所 | Antarctic ship-borne gravity measurement calibration method |
| CN111505727A (en) * | 2020-04-16 | 2020-08-07 | 清华大学 | Vibration compensation method and system based on multi-sensor data fusion |
| CN111679334A (en) * | 2020-06-19 | 2020-09-18 | 中国地震局地震预测研究所 | Absolute gravitational acceleration compensation method and device |
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