CN106383367A - Absolute gravity measurement method and apparatus thereof - Google Patents
Absolute gravity measurement method and apparatus thereof Download PDFInfo
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- CN106383367A CN106383367A CN201510462931.8A CN201510462931A CN106383367A CN 106383367 A CN106383367 A CN 106383367A CN 201510462931 A CN201510462931 A CN 201510462931A CN 106383367 A CN106383367 A CN 106383367A
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Abstract
The invention discloses an absolute gravity measurement method and an apparatus thereof. The absolute gravity measurement method comprises the following steps that a time acquisition unit detects falling time t of a detected falling body and sends the t to a host computer; an optical interferometer detects a falling displacement signal d1(t) of the detected falling body relative to a reference prism and sends the signal d1(t) to the host computer; a vibration detection unit detects a displacement signal d2(t) of the reference prism which is vibrated along with ground and sends the signal d2(t) to the host computer; the host computer uses the signal d2(t) to compensate the signal d1(t) so as to acquire a displacement signal d(t) of the detected falling body relative to the ground; and the host computer acquires a gravitational acceleration g according to the signal d(t) and the t. In the invention, a ground vibration signal is compensated to a falling displacement of the detected falling body, measurement of a detected falling body displacement is accurate, measurement times can be greatly reduced and the accurate gravitational acceleration is acquired.
Description
Technical field
The present invention relates to gravity measurement field, more particularly, to a kind of absolute gravity measurement method and dress
Put.
Background technology
The principle of current optical interference absolute gravimeter is accurate measurement in high vacuum conditions
Tested the falling bodies time of free-falling experience and displacement in gravitational field, then according to formula (1)：
S (t)=s0+v0t+1/2gt2(1)
It is calculated g, wherein t is the fall time of tested falling bodies, s (t) is that the tested falling bodies of t are relative
In the displacement on ground, s0For the initial displacement of tested falling bodies, v0Initial velocity for tested falling bodies.
Principle of optical interference detects that the principle of tested falling bodies displacement is as shown in Figure 1.The laser of optical interdferometer
Light beam sends from laser instrument 101, is divided into two bundles by spectroscope (Beam Splitter) 102,
Reflection a branch of for measuring beam (dotted line represents), transmission a branch of for reference beam (solid line table
Show).Measuring beam be irradiated to tested falling bodies 103 (tested falling bodies 103 are rectangular three-dimensional prism,
It is placed in vacuum intracavity) reflect, it is irradiated to reference prism 104 through spectroscope 102, and through ginseng
Examine prism 104 and reflex to spectroscope 102, converge with reference beam and be irradiated to photodetector 105
On.When tested falling bodies 103 freely falling body, the measuring beam reflecting and the reference light of transmission
Bundle interferes, and produces interference fringe.Photodetector 105 is by tested falling bodies 103 when falling
Between the interference fringe number that produces of t be converted to the signal of telecommunication, the number correspondence of wherein interference fringe is tested
The whereabouts displacement of falling bodies 103, the time set of absolute gravimeter records the time of whereabouts simultaneously.Neglect
Slightly in the case of gravity acceleration g change spatially, using formula (1), you can obtain
The numerical value of gravity acceleration g.
But in practical operation, due to reasons such as Earth Surface vibrations, reference prism 104 is relatively
Also displacement can be produced in earth center, this allows for the tested falling bodies 103 recording with respect to reference to rib
The displacement of mirror 104 and tested falling bodies 103 occur partially with respect between the actual displacement of earth center
Difference, the numerical value of the gravity acceleration g therefore obtaining is also not accurate enough.
Being accurately positioned by frame for movement in prior art can be by the horizontal amplitude of oscillation control of tested falling bodies
System is in allowed band, but cannot avoid the vertical direction that reference prism produces with ground vibration
Displacement.Fig. 2 is the principle schematic of vibration compensation method.As shown in Fig. 2 optical interdferometer records
Be the displacement d that tested falling bodies 103 are with respect to reference prism 1041, and in actual measurement, reference
Prism 104 also can produce displacement d with ground vibration2.Because reference prism 104 is with ground vibration
Cause the tested falling bodies actual whereabouts displacement that interferometer is surveyed inaccurate, cause final gravity to accelerate
Angle value measurement is inaccurate, and in prior art, a kind of method is to need to take multiple measurements, and result is made even
The method of average is eliminating the impact to degree of accuracy for the single measurement.Because the method needs to rely in a large number
Experiment number, and multiple measurement results dispersibility (in meterological A class uncertainty come
Weigh) ratio is larger, and effect is not ideal enough.Another kind of improved method is using low frequency vibration measuring sensing
Device, measurement reference prism, with respect to the displacement on ground, then compensates.However, as Fig. 3 institute
Show, the method medium and low frequency vibration-measuring sensor has difference to the vibration of different frequency, different directions again
Frequency response, exist decay and phase drift hence in so that vibration measurement is not accurate enough.
Content of the invention
The invention provides a kind of absolute gravity measurement method and apparatus, ground vibration signal is mended
Repay in tested falling bodies whereabouts displacement, the measurement of tested falling bodies displacement is more accurate, and then can
More accurately measure acceleration of gravity.
According to an aspect of the invention, it is provided a kind of absolute gravity measurement method, including：
Time collecting unit detects fall time t of tested falling bodies, and t is sent to host computer；
Optical interdferometer detects the whereabouts displacement signal d that tested falling bodies are with respect to reference prism1(t),
And by signal d1T () is sent to host computer；
Vibration measuring unit detects the displacement signal d with ground vibration for the reference prism2(t), and by signal
d2T () is sent to host computer；
Host computer utilizes signal d2T () is to signal d1T () compensates, obtain tested falling bodies with respect to
Displacement signal d (t) on ground；
Host computer obtains gravity acceleration g according to signal d (t) and t.
In one embodiment, host computer utilizes signal d2T () is to signal d1T () compensates, obtain
Include to tested falling bodies with respect to the step of displacement signal d (t) on ground：
Tested using test signal, the transfer function H (f) obtaining vibration measuring unit is in frequency k
Amplitude-frequency characteristic Hk(f) and phase-frequency characteristic ΦkF (), wherein 1≤k≤n, n are the frequency needing test
Points；
According to Hk(f) and ΦkF () is to signal d2T () carries out inverting, obtain inverting signal d2’(t)；
Using inverting signal d2' (t) to signal d1T () compensates, obtain tested falling bodies with respect to
Displacement signal d (t) on ground.
In one embodiment, tested using test signal, obtained the transmission of vibration measuring unit
Function H (f) is in amplitude-frequency characteristic H of frequency kk(f) and phase-frequency characteristic ΦkF the step of () includes：
By test signal x (t) and corresponding output signal y (t), and x (t) and y (t) is transformed to frequency
Domain signal X (f) and Y (f)；
The transfer function H (f) obtaining vibration measuring unit according to X (f) and Y (f) is special in the amplitude-frequency of frequency k
Property Hk(f) and phase-frequency characteristic Φk(f), wherein, H (f)=Y (f)/X (f).
In one embodiment, according to Hk(f) and ΦkF () is to signal d2T () carries out inverting, obtain
Inverting signal d2' step of (t) includes：
To signal d2T () carries out digital collection；
By the signal d after digital collection2T () is multiplied by the first window function, and be transformed to frequency-region signal
D2(f)；
On each frequency k, by signal D2F the range value of () is divided by HkF (), phase value deducts
ΦkF (), obtains revised 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) be transformed to time-domain signal, traveling wave of going forward side by side shape is spelled
Connect 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 a further aspect in the invention, there is provided a kind of absolute gravity measurement device, including：
Time collecting unit, optical interdferometer, vibration measuring unit and host computer, wherein：
Time collecting unit, for detecting fall time t of tested falling bodies, and t is sent to
Position machine；
Optical interdferometer, for detecting the whereabouts displacement signal that tested falling bodies are with respect to reference prism
d1(t), and by signal d1T () is sent to host computer；
Vibration measuring unit, for detecting the displacement signal d with ground vibration for the reference prism2(t), and will
Signal d2T () is sent to host computer；
Host computer, for using signal d2T () is to signal d1T () compensates, obtain tested fall
Body phase is for displacement signal d (t) on ground；Gravity acceleration g is obtained according to signal d (t) and t.
In one embodiment, host computer specifically includes test module, inverting module and compensates meter
Calculate module, wherein：
Test module, for being tested, obtains the transmission letter of vibration measuring unit using test signal
Number H (f) is in amplitude-frequency characteristic H of frequency kk(f) and phase-frequency characteristic Φk(f), wherein 1≤k≤n, n
For needing the frequency number of test；
Inverting module, for according to Hk(f) and ΦkF () is to signal d2T () carries out inverting, obtain anti-
Drill signal d2’(t)；
Compensation calculation module, for using inverting signal d2' (t) to signal d1T () compensates,
Obtain displacement signal d (t) that tested falling bodies are with respect to ground；Gravity is obtained according to signal d (t) and t
Acceleration g.
In one embodiment, test module is specifically for by test signal x (t) and defeated accordingly
Go out signal y (t) and be transformed to frequency domain signal X (f) and Y (f)；Vibration measuring list is obtained according to X (f) and Y (f)
The transfer function H (f) of unit is in amplitude-frequency characteristic H of frequency kk(f) and phase-frequency characteristic Φk(f), wherein,
H (f)=Y (f)/X (f).
In one embodiment, inverting module is specifically for signal d2T () carries out digital collection；Will
Signal d after digital collection2T () is multiplied by the first window function, and be transformed to frequency-region signal D2(f)；?
On each frequency k, by signal D2F the range value of () is divided by HkF (), phase value deducts Φk(f),
Obtain revised frequency-region signal D2’(f)；By signal D2' (f) be multiplied by the second window function；To be multiplied by
The signal D of the second window function2' (f) be transformed to time-domain signal, and carry out waveform concatenation and baseline is repaiied
Just, obtain inverting signal d2’(t).
In one embodiment, the first window function and the second window function are Hanning window function.
The invention provides a kind of absolute gravity measurement method and apparatus, ground vibration signal is mended
Repay in tested falling bodies whereabouts displacement, so that the whereabouts displacement recording is closer to actual
The whereabouts displacement of tested falling bodies, can substantially reduce pendulous frequency, obtain more accurate gravity
Acceleration.
Brief description
For the technical scheme being illustrated more clearly that in the embodiment of the present invention, below will to embodiment or
In description the accompanying drawing of required use be briefly described it should be apparent that, below describe in attached
Figure is only some embodiments of the present invention, for those of ordinary skill in the art, is not paying
On the premise of going out creative labor, other accompanying drawings can also be obtained according to these accompanying drawings.
Fig. 1 is the schematic diagram of optical interference Cleaning 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 an 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 testing vibration measuring unit transmission function Frequency Response in the present invention.
Fig. 7 is the method schematic diagram that in the present invention, signal is carried out with inverting.
Fig. 8 is the schematic diagram of an embodiment of absolute gravity measurement device of the present invention.
Fig. 9 is the schematic diagram of absolute gravity measurement one embodiment of device host computer of the present invention.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, to the technical scheme in the embodiment of the present invention
It is clearly and completely described it is clear that described embodiment is only present invention part reality
Apply example, rather than whole embodiments.Description at least one exemplary embodiment is real below
It is merely illustrative on border, never as any limit to the present invention and its application or use
System.Based on the embodiment in the present invention, those of ordinary skill in the art are not making creative labor
The every other embodiment being obtained under the premise of dynamic, broadly falls into the scope of protection of the invention.
Unless specifically stated otherwise, the part otherwise illustrating in these embodiments and the phase of step
Arrangement, numerical expression and numerical value are not limited the scope of the invention.
Fig. 4 is the schematic diagram of an embodiment of absolute gravity measurement method of the present invention.Preferably
, the method and step of the present embodiment can be executed by the absolute gravity measurement device of the present invention, including：
Step 401, time collecting unit detects fall time t of tested falling bodies1, and by t1Send out
Give host computer.
Preferably, time collecting unit adopts high accuracy rubidium clock, to improve the precision of measure of time.
And using synchronous triggering signal it is ensured that the synchro measure of optical interdferometer and vibration measuring unit.
Step 402, optical interdferometer detects the whereabouts displacement that tested falling bodies are with respect to reference prism
Signal d1(t), and by signal d1T () is sent to host computer.
Preferably, optical interdferometer is Michelson laser interferometer.
Step 403, vibration measuring unit detects the displacement signal d with ground vibration for the reference prism2(t),
And by signal d2T () is sent to host computer.
Step 404, host computer utilizes signal d2T () is to signal d1T () compensates, obtain by
Survey displacement signal d (t) that falling bodies are with respect to ground.
For example, host computer according to reference prism with ground vibration displacement signal d2T () is to tested
Falling bodies are with respect to the whereabouts displacement signal d of reference prism1T () compensates, obtain tested falling bodies
Displacement signal d (t) with respect to ground.When reference prism is with the displacement signal d of ground vibration2(t)
With tested falling bodies with respect to reference prism whereabouts displacement signal d1(t) in the same direction when,
D (t)=d1(t)+|d2(t)|；When reversely, 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 on signal d (t) and t respectively1, t2And t3,
Corresponding three displacement point d (t1), d (t2) and d (t3), method of least square is utilized according to formula (1)
Matching obtains term coefficient twice, is multiplied by 2 and is gravity acceleration g1.Repeatedly fallen to surveying
Examination, taking n times test as a example, obtains acceleration gi, wherein 1≤i≤N, n times result is taken
Meansigma methodss, you can obtain the value of gravity acceleration g.Those skilled in the art it will be appreciated that
Can be according to required precision and experimental conditions, it is secondary with measure to determine the time point number chosen
Number, and how to obtain gravity acceleration g using least square fitting.
The absolute gravity measurement method of the present invention, by reference prism with ground vibration bit shift compensation
To in the whereabouts displacement of tested falling bodies, so that the whereabouts displacement recording is closer to actual
The whereabouts displacement of tested falling bodies, can substantially reduce pendulous frequency, obtain more accurate gravity
Acceleration.
Fig. 5 is the schematic diagram of an embodiment of absolute gravity measurement method of the present invention.Preferably
, the method and step of the present embodiment can be executed by the absolute gravity measurement device of the present invention, including：
Step 501, time collecting unit detects fall time t of tested falling bodies, and t is sent out
Give host computer.
Preferably, detect fall time t of tested falling bodies using high accuracy rubidium clock, during improving
Between measurement precision.
Step 502, optical interdferometer detects the whereabouts displacement that tested falling bodies are with respect to reference prism
Signal d1(t), and by signal d1T () is sent to host computer.
Step 503, vibration measuring unit detects the displacement signal d with ground vibration for the reference prism2(t)
And it is sent to host computer.
Step 504, host computer is tested using test signal, obtains the transmission of vibration measuring unit
Function H (f) is in amplitude-frequency characteristic H of frequency kk(f) and phase-frequency characteristic Φk(f), wherein 1≤k≤n,
N is the frequency number needing test.
Preferably, the scope according to ground vibration, chooses n frequency in transfer function H (f),
Obtain amplitude-frequency characteristic H in each frequency for the H (f)k(f) and phase-frequency characteristic Φk(f) preserve, to use
In signal d2The inverting of (t).
Step 505, host computer is according to Hk(f) and ΦkF () is to signal d2T () carries out inverting, obtain
Inverting signal d2’(t).The inverting signal d obtaining after carrying out inverting2' (t) more accurate.
Step 506, host computer utilizes inverting signal d2' (t) to signal d1T () compensates, obtain
To tested falling bodies with respect to ground displacement signal d (t).
For example, host computer is according to inverting signal d2' (t) to tested falling bodies with respect to reference prism
Whereabouts displacement signal d1T () compensates, obtain the displacement signal that tested falling bodies are with respect to ground
d(t).As inverting signal d2' (t) and tested falling bodies with respect to reference prism whereabouts displacement signal
d1(t) in the same direction when, d (t)=d1(t)+|d2’(t)|；When reversely, 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 on signal d (t) and t respectively1, t2And t3,
Corresponding three displacement point d (t1), d (t2) and d (t3), method of least square is utilized according to formula (1)
Matching obtains term coefficient twice, is multiplied by 2 and is gravity acceleration g1.Repeatedly fallen to surveying
Examination, taking n times test as a example, obtains acceleration gi, wherein 1≤i≤N, n times result is taken
Meansigma methodss, you can obtain the value of gravity acceleration g.Those skilled in the art it will be appreciated that
Can be according to required precision and experimental conditions, it is secondary with measure to determine the time point number chosen
Number, and how to obtain gravity acceleration g using least square fitting.
The absolute gravity measurement method of the present invention, by signal d2T () inverting, to signal
It is modified in the amplitude of frequency domain and phase place, obtain more accurate inverting signal d2' (t), from
And make the whereabouts displacement that records closer to the whereabouts displacement of actual tested falling bodies, Neng Gouxian
Write and reduce pendulous frequency, obtain more accurate acceleration of gravity.
Fig. 6 is in an embodiment of absolute gravity measurement method of the present invention, test transmission letter
The schematic diagram of the method for number Frequency Response, as shown in fig. 6, include：
Step 601, test signal x (t) and corresponding output signal y (t) are transformed to frequency domain letter
Number X (f) and Y (f).
Preferably, Fourier transformation, fast Fourier transform, Laplace transform can be adopted
Etc. method, time-domain signal x (t) and y (t) are transformed to frequency domain signal X (f) and Y (f).
Step 602, obtains the transfer function H (f) of vibration measuring unit in frequency according to X (f) and Y (f)
Amplitude-frequency characteristic H of kk(f) and phase-frequency characteristic Φk(f), wherein, H (f)=Y (f)/X (f).
Preferably, the frequency characteristic according to ground vibration and required precision, chooses frequency points n
And the frequency values of each frequency k.Those skilled in the art are it will be appreciated that obtain vibration measuring
After the transfer function H (f) of unit, amplitude-frequency characteristic H in frequency k can be obtained furtherk(f)
With phase-frequency characteristic Φk(f).
Fig. 7 is in an embodiment of absolute gravity measurement method of the present invention, to signal inverting
The schematic diagram of method.Preferably, the method for the present embodiment is carried out by host computer in the present invention, bag
Include：
Step 701, to signal d2' (t) carry out digital collection.
Step 702, by the signal d after digital collection2T () is multiplied by the first window function, and be transformed to
Frequency-region signal D2(f).Wherein, by signal d2T () is transformed to frequency-region signal D2F () can adopt Fu
In the method such as leaf transformation, fast Fourier transform, Laplace transform.
Preferably, the first window function is Hanning window function.
Step 703, on each frequency k, by signal D2F the range value of () is divided by Hk(f),
Phase value deducts ΦkF (), obtains revised frequency-region signal D2’(f).By to signal D2(f)
Be modified, amplitude and phase place are compensated so as to get signal D2' planarization of (f) signal,
Frequency range is wider, and certainty of measurement is higher.
Step 704, by signal D2' (f) be multiplied by the second window function.
Step 705, will be multiplied by the signal D of the second window function2' (f) be transformed to time-domain signal, and
Carry out waveform concatenation and base wavelet, obtain inverting signal d2’(t).
Preferably, the second window function is Hanning window function.Through the correction of step 703-704,
The inverting signal d that step 705 obtains2' (t) more accurate.Wherein, by frequency-region signal D2’(f)
It is transformed to signal d2' (t) can adopt inverse Fourier transform, inverse fast Fourier transform, La Pu
The methods such as Lars inverse transformation.
The inverting by signal for the absolute gravity measurement method of the present invention, can be by reference prism phase
For ground displacement real-Time Compensation in the whereabouts displacement of tested falling bodies, the tested falling bodies that obtain
More accurate with respect to the displacement on ground, effectively reduce experiment number, the acceleration of gravity of matching
The numerical value of g is also more accurate.
Fig. 8 is the schematic diagram of an embodiment of absolute gravity measurement device of the present invention.As figure
Shown in 8, including：Time collecting unit 801, optical interdferometer 802, vibration measuring unit 803
With host computer 804, wherein：
Time collecting unit 801 is used for detecting fall time t of tested falling bodies, and t is sent to
Host computer 804.
Preferably, time collecting unit 801 is high accuracy rubidium clock, to improve the essence of measure of time
Degree.
Optical interdferometer 802 is used for detecting the displacement letter in whereabouts with respect to reference prism for the tested falling bodies
Number d1(t), and by signal d1T () is sent to host computer 804.
Preferably, optical interdferometer 802 is Michelson laser interferometer.
Vibration measuring unit 803 is used for detecting the displacement signal d with ground vibration for the reference prism2(t), and
By signal d2T () is sent 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 survey
Measure the time synchronized it is ensured that measuring.
Host computer 804 is used for using signal d2T () is to signal d1T () compensates, obtain tested fall
Body phase is for displacement signal d (t) on ground, and obtains gravity acceleration g according to signal d (t) and t.
For example, in one embodiment, host computer 804 according to reference prism with ground vibration
Displacement signal d2(t) to tested falling bodies with respect to reference prism whereabouts displacement signal d1(t) carry out
Compensate, obtain displacement signal d (t) that tested falling bodies are with respect to ground.When reference prism is with ground
The displacement signal d of vibration2T () and tested falling bodies are with respect to the whereabouts displacement signal of reference prism
d1(t) in the same direction when, d (t)=d1(t)+|d2(t)|；When reversely, d (t1)=d1(t)-|d2(t)|.Host computer
804 choose three time point t on signal d (t) and t respectively1, t2And t3, corresponding three positions
Move point d (t1), d (t2) and d (t3), obtain two according to formula (1) using least square fitting
Secondary term coefficient, is multiplied by 2 and is gravity acceleration g1.Repeatedly fallen to testing, with n times
As a example test, obtain acceleration gi, wherein 1≤i≤N, to n times results 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 essence
Degree requires and experimental conditions, determines the time point number chosen and the number of times of measurement, and how
Obtain gravity acceleration g using least square fitting.
The absolute gravity measurement device of the present invention, reference prism is mended relative to the vibration displacement on ground
Repay in tested falling bodies whereabouts displacement, so that the whereabouts displacement recording is closer to actual
The whereabouts displacement of tested falling bodies, can substantially reduce pendulous frequency, obtain more accurate gravity
Acceleration.
Fig. 9 is an embodiment of host computer 804 in the absolute gravity measurement device of the present invention
Exemplary plot.As shown in figure 9, host computer 804 includes test module 8041, inverting module 8042
With compensation calculation module 8043, wherein：
Test module 8041 is used for being tested using test signal, obtains vibration measuring unit 803
Transfer function H (f) frequency k amplitude-frequency characteristic Hk(f) and phase-frequency characteristic Φk(f), wherein
1≤k≤n, n are the frequency number needing test.
Preferably, test module 8041 is by test signal x (t) and corresponding output signal y (t)
It is transformed to frequency domain signal X (f) and Y (f)；Obtain the biography of vibration measuring unit 803 according to X (f) and Y (f)
Delivery function H (f) is in amplitude-frequency characteristic H of frequency kk(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 ΦkF () is to signal d2T () carries out inverting, obtain
To inverting signal d2’(t).
Preferably, inverting module 8042 is to signal d2T () carries out digital collection；By digital collection
Signal d afterwards2T () is multiplied by the first window function, and be transformed to frequency-region signal D2(f)；In each frequency
On point k, by signal D2F the range value of () is divided by HkF (), phase value deducts ΦkF (), obtains
Revised frequency-region signal D2’(f)；By signal D2' (f) be multiplied by the second window function；Will be multiplied by
The signal D of two window functions2' (f) be transformed to time-domain signal, and carry out waveform concatenation and baseline is repaiied
Just, 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 for using inverting signal d2' (t) to signal d1T () is mended
Repay, obtain displacement signal d (t) that tested falling bodies are with respect to ground；Obtained according to signal d (t) and t
To gravity acceleration g.
For example, in one embodiment, as inverting signal d2' (t) and tested falling bodies are with respect to ginseng
Examine the whereabouts displacement signal d of prism1(t) in the same direction when, d (t)=d1(t)+|d2’(t)|；When reversely,
D (t)=d1(t)-|d2’(t)|.Choose three time point t respectively on signal d (t) and t1, t2And t3,
Corresponding three displacement point d (t1), d (t2) and d (t3), method of least square is utilized according to formula (1)
Matching obtains term coefficient twice, is multiplied by 2 and is gravity acceleration g1.Repeatedly fallen to surveying
Examination, taking n times test as a example, obtains acceleration gi, wherein 1≤i≤N, n times result is taken
Meansigma methodss, you can obtain the value of gravity acceleration g.Those skilled in the art it will be appreciated that
Can be according to required precision and experimental conditions, it is secondary with measure to determine the time point number chosen
Number, and how to obtain gravity acceleration g using least square fitting.
The absolute gravity measurement method of the present invention, by signal d2T () inverting, exists to signal
The amplitude of frequency domain and phase place are modified, and obtain more accurate inverting signal d2' (t), so that
The whereabouts displacement that must record, closer to the whereabouts displacement of actual tested falling bodies, can significantly subtract
Few pendulous frequency, obtains more accurate acceleration of gravity.
With reference to Fig. 5-Fig. 9, the absolute gravity measurement method and apparatus of the present invention is shown
Example property explanation.
Time collecting unit 801 carries out timing using high accuracy rubidium clock, and using synchronous triggering letter
Number guarantee optical interdferometer 802 and vibration measuring unit 803 synchro measure.When tested falling bodies are in vacuum
When intracavity does the movement of falling object, optical interdferometer 802 detects tested falling bodies with respect to reference to rib
The whereabouts displacement signal d of mirror1(t), and by signal d1T () is sent to host computer 804.Vibration measuring list
Unit 803 detection reference prism is with the signal d of the displacement of ground vibration2(t) it is sent to host computer
804.
The test module 8041 of host computer 804 is tested to vibration measuring unit 803.To test
Signal x (t) inputs vibration measuring unit 803, obtains corresponding output signal y (t), using quick Fu
In leaf transformation method, time-domain signal x (t) and y (t) are transformed to frequency domain signal X (f) and Y (f),
And then obtain the transfer function H (f) of vibration measuring unit 803.Frequency range according to ground vibration
Require with measuring accuracy, choose n frequency, obtain amplitude-frequency characteristic H of each frequency kk(f)
With phase-frequency characteristic Φk(f), wherein 1≤k≤n.By Hk(f) and ΦkF () preserves, to use afterwards
In signal inverting.
Inverting module 8042 is to signal d2T () is multiplied by the first window function (example after carrying out digital collection
As Hanning window function), and be frequency-region signal D using fast Fourier transform2(f).Every
On individual frequency k, inverting module 8042 is by signal D2F the range value of () is divided by Hk(f), phase place
Value deducts Φk(f), and then obtain revised frequency-region signal D2' (f), by signal D2' (f) be multiplied by
Carry out inverse fast Fourier transform, after converting after second window function (such as Hanning window function)
The time domain waveform obtaining carries out seamless spliced and base wavelet, obtains inverting signal d2’(t).
Compensation calculation module 8043 utilizes inverting signal d2' (t) to signal d1T () compensates,
Obtain displacement signal d (t) that tested falling bodies are with respect to ground；For example, on signal d (t) and t
Choose three time point t respectively1, 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), is multiplied by 2 and attaches most importance to
Power acceleration g1.Repeatedly fallen to testing, taking n times test as a example, obtained acceleration gi,
Wherein 1≤i≤N, to n times results averaged, you can obtain the value of gravity acceleration g.
Those skilled in the art are it will be appreciated that can determine according to required precision and experimental conditions
The time point number chosen and the number of times of measurement, and how to be obtained using least square fitting
Gravity acceleration g.
The inverting by signal for the absolute gravity measurement method and apparatus of the present invention, can be by reference
Prism with respect to ground displacement real-Time Compensation in the whereabouts displacement of tested falling bodies so that
The whereabouts displacement recording, closer to the whereabouts displacement of actual tested falling bodies, can substantially reduce
Pendulous frequency, obtains more accurate acceleration of gravity.
One of ordinary skill in the art will appreciate that realizing all or part step of above-described embodiment
Suddenly can be completed it is also possible to the hardware being instructed correlation by program is completed by hardware, institute
The program stated can be stored in a kind of computer-readable recording medium, and storage mentioned above is situated between
Matter can be read only memory, disk or CD etc..
Description of the invention is given for the sake of example and description, and is not exhaustively
Or limit the invention to disclosed form.Many modifications and variations are for the common skill of this area
It is obvious for art personnel.Select and describe the principle that embodiment is in order to the present invention is more preferably described
And practical application, and make those of ordinary skill in the art it will be appreciated that the present invention is thus design is suitable
In the various embodiments with various modifications for the special-purpose.
Claims (10)
1. a kind of absolute gravity measurement method is it is characterised in that include：
Time collecting unit detects fall time t of tested falling bodies, and t is sent to host computer；
Optical interdferometer detects the whereabouts displacement signal d that tested falling bodies are with respect to reference prism1(t),
And by signal d1T () is sent to host computer；
Vibration measuring unit detects the displacement signal d with ground vibration for the reference prism2(t), and by signal
d2T () is sent to host computer；
Host computer utilizes signal d2T () is to signal d1T () compensates, obtain tested falling bodies with respect to
Displacement signal d (t) on ground；
Host computer obtains gravity acceleration g according to signal d (t) and t.
2. method according to claim 1 is it is characterised in that host computer utilizes signal
d2T () is to signal d1T () compensates, obtain displacement signal d (t) that tested falling bodies are with respect to ground
Step include：
Tested using test signal, the transfer function H (f) obtaining vibration measuring unit is in frequency k
Amplitude-frequency characteristic Hk(f) and phase-frequency characteristic ΦkF (), wherein 1≤k≤n, n are the frequency needing test
Points；
According to Hk(f) and ΦkF () is to signal d2T () carries out inverting, obtain inverting signal d2’(t)；
Using inverting signal d2' (t) to signal d1T () compensates, obtain tested falling bodies with respect to
Displacement signal d (t) on ground.
3. method according to claim 2 is it is characterised in that carried out using test signal
Test, obtains amplitude-frequency characteristic H in frequency k for the transfer function H (f) of vibration measuring unitk(f) and phase frequency
Characteristic ΦkF the step of () includes：
By test signal x (t) and corresponding output signal y (t) be transformed to frequency domain signal X (f) and
Y(f)；
The transfer function H (f) obtaining vibration measuring unit according to X (f) and Y (f) is special in the amplitude-frequency of frequency k
Property Hk(f) and phase-frequency characteristic Φk(f), wherein, H (f)=Y (f)/X (f).
4. method according to claim 2 is it is characterised in that according to Hk(f) and Φk(f)
To signal d2T () carries out inverting, obtain inverting signal d2' step of (t) includes：
To signal d2T () carries out digital collection；
By the signal d after digital collection2T () is multiplied by the first window function, and be transformed to frequency-region signal
D2(f)；
On each frequency k, by signal D2F the range value of () is divided by HkF (), phase value deducts
ΦkF (), obtains revised 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) be transformed to time-domain signal, traveling wave of going forward side by side shape is spelled
Connect and base wavelet, obtain inverting signal d2’(t).
5. method according to claim 4 is it is characterised in that the first window function and second
Window function is Hanning window function.
6. a kind of absolute gravity measurement device is it is characterised in that include：Time collecting unit,
Optical interdferometer, vibration measuring unit and host computer, wherein：
Time collecting unit, for detecting fall time t of tested falling bodies, and t is sent to
Position machine；
Optical interdferometer, for detecting the whereabouts displacement signal that tested falling bodies are with respect to reference prism
d1(t), and by signal d1T () is sent to host computer；
Vibration measuring unit, for detecting the displacement signal d with ground vibration for the reference prism2(t), and will
Signal d2T () is sent to host computer；
Host computer, for using signal d2T () is to signal d1T () compensates, obtain tested falling bodies
Displacement signal d (t) with respect to ground；Gravity acceleration g is obtained according to signal d (t) and t.
7. device according to claim 6 is it is characterised in that host computer specifically includes survey
Die trial block, inverting module and compensation calculation module, wherein：
Test module, for being tested, obtains the transmission letter of vibration measuring unit using test signal
Number H (f) is in amplitude-frequency characteristic H of frequency kk(f) and phase-frequency characteristic Φk(f), wherein 1≤k≤n, n
For needing the frequency number of test；
Inverting module, for according to Hk(f) and ΦkF () is to signal d2T () carries out inverting, obtain anti-
Drill signal d2’(t)；
Compensation calculation module, for using inverting signal d2' (t) to signal d1T () compensates,
Obtain displacement signal d (t) that tested falling bodies are with respect to ground；Gravity is obtained according to signal d (t) and t
Acceleration g.
8. device according to claim 7 it is characterised in that test module specifically for
Test signal x (t) and corresponding output signal y (t) are transformed to frequency domain signal X (f) and Y (f)；Root
Obtain amplitude-frequency characteristic H in frequency k for the transfer function H (f) of vibration measuring unit according to X (f) and Y (f)k(f)
With phase-frequency characteristic Φk(f), wherein, H (f)=Y (f)/X (f).
9. device according to claim 7 it is characterised in that inverting module specifically for
To signal d2T () carries out digital collection；By the signal d after digital collection2T () is multiplied by the first window function,
And it is transformed to frequency-region signal D2(f)；On each frequency k, by signal D2F the range value of () removes
With HkF (), phase value deducts ΦkF (), obtains revised 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) be transformed to time domain letter
Number, and carry out waveform concatenation and base wavelet, obtain inverting signal d2’(t).
10. device according to claim 9 is it is characterised in that the first window function and
Two window functions are Hanning window function.
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