CN104122789A - High-precision distributed synchronous clock system and method - Google Patents
High-precision distributed synchronous clock system and method Download PDFInfo
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- CN104122789A CN104122789A CN201410369304.5A CN201410369304A CN104122789A CN 104122789 A CN104122789 A CN 104122789A CN 201410369304 A CN201410369304 A CN 201410369304A CN 104122789 A CN104122789 A CN 104122789A
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Abstract
The invention discloses a high-precision distributed synchronous clock system and method. A distributed synchronization method combining GPS (global positioning system) with a constant-temperature crystal oscillator is adopted, that is, a GPS receiver module resolves time information and positioning information and generates 1PPS (pulse per second) signals to rectify local 1PPS signals generated by a constant-temperature crystal oscillator module, so that the local 1PPS signals and the 1PPS signals are synchronous. Thus, a viewer with the high-precision distributed synchronous clock system is capable of realizing multipoint distributed synchronization, high in synchronization accuracy and capable of accurately recording time during synchronous acquisition of data. Furthermore, spatial dimension of data acquiring points can be accurately positioned. After one or more GPSs fail, pulse per second generated by the local constant-temperature crystal oscillator is used for synchronization instead of the 1PPS signals, and effective time of synchronization can reach more than half an hour.
Description
Technical field
The present invention relates to fine motion prospecting technique field, be specifically related to a kind of high precision distributed synchronization clock system and method.
Background technology
Epigeosphere constantly exists non-seismic faint vibrations and is called fine motion.Research shows, the structure of shallow crust medium is reflected in microtremor observation, can infer the structure on stratum by the weak vibration situation of geologize medium, forms fine motion investigation method.Fine motion investigation method utilizes the collection of microtremor observation instrument to receive the incoming wave of earth's surface all directions, by spatial autocorrelation (SPAC) method, extracts dispersion curve, obtains the geophysical reconnaissance method of S Wave Velocity Structure through inverting.By SPAC method during to the auspicious Leibo of fine motion signal extraction dispersion curve, not only require observation array be the regular circular array (as shown in Figure 1, each visualizer distributes along concentric circles, and at least on circumference, uniformly-spaced arrange three visualizers), and the collection of data is had to strict synchronous requirement.
Realizing each visualizer in the array is one of gordian technique of fine motion exploration to the high-precise synchronization of data acquisition.At present, realize the synchronous main method of each visualizer in the array for there being line locking, wireless telecommunications are synchronous, synchronous three kinds of high-precision quartz clock.And these three kinds of synchronous method all exist drawback separately, if any line locking, be difficult to realize remote synchronous; Wireless telecommunications are synchronously subject to such environmental effects; High-precision quartz clock is expensive and the presynchronization time is long, and these drawbacks all, by greatly reducing the precision of exploration, even cause the consequence that cannot survey.
Summary of the invention
Technical matters to be solved by this invention is to provide a kind of high precision distributed synchronization clock system and method, and it can carry out multiple spot distributed synchronization, and has the feature of synchronization accuracy height and good stability.
For addressing the above problem, the present invention is achieved by the following technical solutions:
High precision distributed synchronization clock system, is mainly comprised of GPS receiver module, stability judging module, constant-temperature crystal oscillator module, frequency multiplier module, allocator module, time interval measurement module and digital-to-analog conversion conditioning module; Wherein the temporal information output terminal of GPS receiver module connects visualizer, and the 1PPS signal output part of GPS receiver module is connected with an input end of time interval measurement module through stability judging module; The output terminal of constant-temperature crystal oscillator module connects the input end of allocator module through frequency multiplier module; The output terminal of allocator module is divided into two-way, and a road connects visualizer, another input end of another road tie-time interval measurement module; The output terminal of time interval measurement module connects the input end of digital-to-analog conversion conditioning module, and the output terminal of digital-to-analog conversion conditioning module is connected with the control end of constant-temperature crystal oscillator module.
In said system, described GPS receiver module is also provided with locating information output terminal.
In said system, the temporal information output terminal of described GPS receiver module is connected with a liquid crystal display with locating information output terminal simultaneously.
High precision distributed synchronization clock method based on above-mentioned high precision distributed synchronization clock system, comprises the steps:
Step 1, GPS receiver module calculates temporal information, and this temporal information is sent into visualizer as time mark, and GPS receiver module also produces 1PPS signal and sends into stability judging module simultaneously;
Step 2, stability judging module is carried out stability judgement to 1PPS signal, obtains stable 1PPS signal;
Step 3, the crystal oscillator signal that constant-temperature crystal oscillator module produces, after frequency multiplier module frequency multiplication, then is sent into allocator module and is carried out frequency division and obtain local pps pulse per second signal, and sends into respectively time interval measurement module and visualizer;
Step 4, time interval measurement module is measured the mistiming of 1PPS signal and local pps pulse per second signal;
Step 5, mistiming filtration module carried out after Kalman filtering the measured mistiming, obtained digital-to-analog conversion deviation control amount;
Step 6, digital-to-analog conversion conditioning module, according to obtaining digital-to-analog conversion deviation control amount, is carried out adjustment to the frequency of constant-temperature crystal oscillator, and local pps pulse per second signal is synchronizeed with 1PPS signal.
In said method, described step 1 also further comprises, GPS receiver module calculates locating information, the step of laying with supplementary observation instrument.
In said method, described step 1 also further comprises, the temporal information that GPS receiver module is calculated and locating information are sent into the step that display shows.
Compared with prior art, the present invention has following features:
1, high, the good stability of precision, compares with the synchronous clock that traditional GPS produces, and has higher synchronous clock precision, and after one or many GPS lost efficacy, the effective time that can continue high-precise synchronization is long.
2, multiple spot distributed synchronization, for meeting the needs of data acquisition, can realize at a distance and carrying out synchronously with in-plant a plurality of points simultaneously.
3, location and time interocclusal record, can carry out correct time record and space orientation to distributed each data collection point, the sampling instant of knowing data that can be more cheer and bright, arranges clearer and more definite dimensional orientation is provided for scopic field.
Accompanying drawing explanation
Fig. 1 is microtremor observation array schematic diagram.In figure ,-represent survey line, zero represents measuring point, ● center measuring point represented.
Fig. 2 is high precision distributed synchronization clock system schematic diagram.
Fig. 3 is 1PPS judgement of stability schematic diagram.
Fig. 4 is clock phase-splitting sequential chart.
Embodiment
A kind of high precision distributed synchronization clock system, as shown in Figure 2, mainly by GPS receiver module, stability judging module, constant-temperature crystal oscillator module, frequency multiplier module, allocator module, time interval measurement module, digital-to-analog conversion conditioning module and liquid crystal display, formed.Wherein the locating information output terminal of GPS receiver module is connected with liquid crystal display, and by the locating information calculating, laying that can supplementary observation instrument can be equally spaced each visualizer on circumference.The temporal information output terminal of GPS receiver module connects visualizer, and by the temporal information calculating, the data that can collect visualizer are carried out time mark.The 1PPS signal output part of GPS receiver module is connected with an input end of time interval measurement module through stability judging module.In order can intuitively to show time and locating information, the temporal information output terminal of described GPS receiver module is also connected with a liquid crystal display with locating information output terminal simultaneously.The output terminal of constant-temperature crystal oscillator module connects the input end of frequency multiplier module.The output terminal of frequency multiplier module connects the input end of allocator module.The output terminal of allocator module is divided into two-way, and a road connects visualizer, another input end of another road tie-time interval measurement module.The output terminal of time interval measurement module connects the input end of digital-to-analog conversion conditioning module, and the output terminal of digital-to-analog conversion conditioning module is connected with the control end of constant-temperature crystal oscillator module.
Each visualizer in the fine motion array adopts independently observed pattern, and scopic geophone amplifies by prime amplifier after receiving signal, then by AD converter to synchronous data sampling, can effectively reduce data acquisition error like this.The synchronizing function of synchronous data sampling is completed by GPS and the complementary co-ordination of constant-temperature crystal oscillator.By a high precision distributed synchronization clock system is all installed on every visualizer, can allow many visualizers in same observation array, can carry out multiple spot distributed synchronization, and have very high synchronization accuracy, synchronization accuracy is better than 200ns.And when synchronous data sampling, can carry out correct time record, and can locate accurately the dimensional orientation of data collection point.In addition, the present invention, after one or many GPS receiver modules lost efficacy, utilizes the pulse per second (PPS) that local constant-temperature crystal oscillator produces to replace 1PPS signal to carry out synchronously, more than synchronous working can reach half an hour effective time.
High precision distributed synchronization clock method based on above-mentioned high precision distributed synchronization clock system, comprises the steps:
Step 1, GPS receiver module calculates temporal information and locating information, and this temporal information and locating information are all sent into display and are shown, and temporal information also needs to send into visualizer as time mark.Meanwhile, GPS receiver module also produces 1PPS signal and sends into stability judging module.
Due to the complicacy in field exploration geographic position, synchronized clock system inside comprises locating information, can read locating information from LCDs, by locating information, the exploration point of field regulation is arranged.Be that GPS receiver module calculates locating information, can lay by supplementary observation instrument, can guarantee that like this each visualizer in the same fine motion array can distribute along concentric circles, and uniformly-spaced arrange on circumference.And the temporal information that GPS receiver module calculates, the data that can collect visualizer are carried out time mark.
Because exploration in the wild needs long-time measurement, what collect is a large amount of data, need to store data, by temporal information, the moment of data acquisition is identified, and guarantees not entanglement of data.Be GPS receiver module generation time information, so that each visualizer in the same fine motion array can be synchronized with gps time accurately in time.
Step 2, the 1PPS signal that stability judging module produces GPS receiver module carries out stability judgement, to obtain stable 1PPS signal.
As shown in Figure 3, the counter module in this stability judging module is designed by CPLD the principle of stability judgement, and CLK clock is provided by constant-temperature crystal oscillator.According to constant-temperature crystal oscillator degree of stability in a short time, can reach 10
-12therefore Hz will be very high at the counting precision of 1s inside counting device.At a high level of then counter module output of counting 1s time, open one " wicket " and send into AND circuit, only when effectively second signal arrives, just can obtain real 1PPS signal, eliminate the stochastic error of 1PPS signal, by this thought design, realized 1PPS hardware anti-interference method.
Step 3, the crystal oscillator signal that constant-temperature crystal oscillator module produces, after frequency multiplier module frequency multiplication, then is sent into allocator module and is carried out frequency division and obtain local pps pulse per second signal, and sends into respectively time interval measurement module and visualizer.
Allocator module frequency division out be two frequencies: one for 1PPS comparison, and local pulse per second (PPS) is synchronizeed with 1PPS gradually; The sample frequency of another one during as image data, scopic synchronous data sampling module gathers data by data collection synchronous pulse.
Step 4, time interval measurement module is measured the mistiming of 1PPS signal and local pps pulse per second signal.
In the present embodiment, time measurement module utilizes clock phase-splitting method to measure the mistiming of local pulse per second (PPS) and 1PPS signal.Clock phase-splitting method is that clock is done after certain time-delay, then with the clock after former clock and time delay, signal is counted respectively simultaneously, thereby improves the method for measuring accuracy.Its realization depends on the stability of delay unit, and resolution depends on the delay time of unit delay unit.Fig. 4 is the sequential chart of 4 grades of clock phase-splittings.If clock frequency is 100MHz, the cycle is 10ns.By the clock signal of 100MHz, through 3 time delays, each phase place lags behind 90 °, and delay time is 2.5ns, obtains clock CLK2, CLK3, CLK4, and time delay sum just covers one-period.With the rising edge of SIG, as counting commencing signal, the negative edge of SIG is as count end signal, and CLK1 can remember 4 clocks (rising edge clock number), and measurement result is 40ns, and its resolution is 10ns.Adopt clock phase-splitting method to calculate, 4 road clocks amount to obtain 15 clock period, and rising edge number is 15.Clock is superposed to a road and calculates, Δ T=15 * 2.5=37.5ns, resolution is 2.5ns, by 4 road clock phase-splitting mensuration resolution, compared with 1 road clock, has improved 4 times.
In time interval module, the rising edge that 1PPS signal and local pps pulse per second signal first arrive is as counting commencing signal, and the signal of rear arrival, as count end signal, obtains both mistiming △ T.
Step 5, mistiming filtration module carried out after Kalman filtering the measured mistiming, obtained digital-to-analog conversion (DAC) deviation control amount.
The general expression that the recursion type of Kalman filter is estimated is:
x(k)＝ax(k-1)+ω(k-1) (1)
y(k)＝cx(k)+v(k) (2)
ω (k) is white noise sequence, and a (k), b (k) are the weighting coefficients of estimator,
represent k-1 estimated value constantly, i.e. the k-1 estimated value of △ T constantly,
represent k estimated value constantly, i.e. the estimated value of k △ T constantly, y (k) is k observed reading constantly, i.e. the observed reading of k △ T constantly.All square evaluated error minimums of take are criterion.All square evaluated error is:
X (k) is k signal value constantly, i.e. the k signal value of △ T constantly, and by (3) formula substitution (4) formula, the partial derivative that makes a (k), b (k) be zero, must
Solve:
a(k)＝a[1-cb(k)] (7)
Initial state estimation value
optimal estimation value be the mean value of the x zero hour (k) sequence, start, after a period of time, △ T to be stored, the mean value that obtains △ T is exactly
optimal estimation, thus all square evaluated error initialization value P (0) further can be obtained.
system noise covariance, minimum for guaranteeing the square error of estimator,
can be determined by experiment,
observation noise covariance,
value is 1.In native system, because the short-term stability of constant-temperature crystal oscillator is fine, frequency change is very little, so observed parameter c value is 1, and in signal model, constant a value is also 1.Determine these parameters, Kalman filter is carried out filtering to mistiming △ T, obtains DAC deviation control amount.
Step 6, digital-to-analog conversion conditioning module, according to obtaining digital-to-analog conversion deviation control amount, is finely tuned the frequency of constant-temperature crystal oscillator, local pps pulse per second signal is synchronizeed, so that the data collection synchronous pulse that each visualizer obtains is also synchronous with 1PPS signal.
Complicacy and unpredictability due to field geology exploration, after one or many GPS lost efficacy, by utilizing local pps pulse per second signal to replace 1PPS signal, record the GPS out-of-service time simultaneously, the data that gather are also carried out to mark, represent that these data are to gather after GPS loses efficacy.When again receiving after gps signal, by the mistiming of local pulse per second (PPS) and 1PPS signal is carried out to Kalman filtering, synchronous clock precision can revert to rapidly the synchronization accuracy before GPS lost efficacy.
The distributed synchronization mode that this method has adopted GPS to combine with constant-temperature crystal oscillator, this synchronous clock can carry out multiple spot distributed synchronization, and there is very high synchronization accuracy, synchronization accuracy is better than 200ns, when synchronous data sampling, can carry out correct time record, and can locate accurately the dimensional orientation of data collection point.After one or many GPS lost efficacy, utilize the pulse per second (PPS) that local constant-temperature crystal oscillator produces to replace 1PPS signal to carry out synchronously, more than synchronous working can reach half an hour effective time.
Claims (6)
1. high precision distributed synchronization clock system, is characterized in that: mainly GPS receiver module, stability judging module, constant-temperature crystal oscillator module, frequency multiplier module, allocator module, time interval measurement module and digital-to-analog conversion conditioning module, consist of; Wherein the temporal information output terminal of GPS receiver module connects visualizer, and the 1PPS signal output part of GPS receiver module is connected with an input end of time interval measurement module through stability judging module; The output terminal of constant-temperature crystal oscillator module connects the input end of allocator module through frequency multiplier module; The output terminal of allocator module is divided into two-way, and a road connects visualizer, another input end of another road tie-time interval measurement module; The output terminal of time interval measurement module connects the input end of digital-to-analog conversion conditioning module, and the output terminal of digital-to-analog conversion conditioning module is connected with the control end of constant-temperature crystal oscillator module.
2. high precision distributed synchronization clock system according to claim 1, is characterized in that: described GPS receiver module is also provided with locating information output terminal.
3. high precision distributed synchronization clock system according to claim 2, is characterized in that: the temporal information output terminal of described GPS receiver module is connected with a liquid crystal display with locating information output terminal simultaneously.
4. the high precision distributed synchronization clock method based on high precision distributed synchronization clock system described in claim 1, is characterized in that comprising the steps:
Step 1, GPS receiver module calculates temporal information, and this temporal information is sent into visualizer as time mark, and GPS receiver module also produces 1PPS signal and sends into stability judging module simultaneously;
Step 2, stability judging module is carried out stability judgement to 1PPS signal, obtains stable 1PPS signal;
Step 3, the crystal oscillator signal that constant-temperature crystal oscillator module produces, after frequency multiplier module frequency multiplication, then is sent into allocator module and is carried out frequency division and obtain local pps pulse per second signal, and sends into respectively time interval measurement module and visualizer;
Step 4, time interval measurement module is measured the mistiming of 1PPS signal and local pps pulse per second signal;
Step 5, mistiming filtration module carried out after Kalman filtering the measured mistiming, obtained digital-to-analog conversion deviation control amount;
Step 6, digital-to-analog conversion conditioning module, according to obtaining digital-to-analog conversion deviation control amount, is carried out adjustment to the frequency of constant-temperature crystal oscillator, and local pps pulse per second signal is synchronizeed with 1PPS signal.
5. high precision distributed synchronization clock method according to claim 4, is characterized in that: described step 1 also further comprises, GPS receiver module calculates locating information, the step of laying with supplementary observation instrument.
6. high precision distributed synchronization clock method according to claim 5, is characterized in that: described step 1 also further comprises, the temporal information that GPS receiver module is calculated and locating information are sent into the step that display shows.
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| CN105549379A (en) * | 2015-12-23 | 2016-05-04 | 中国电子科技集团公司第四十一研究所 | Synchronous measurement apparatus based on high precision time reference triggering and method thereof |
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| CN110850763A (en) * | 2019-11-01 | 2020-02-28 | 中国科学院合肥物质科学研究院 | Distributed timing synchronization method and system for neutral beam injector |
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| CN112782725A (en) * | 2020-12-30 | 2021-05-11 | 华清瑞达（天津）科技有限公司 | High-precision GPS synchronization maintaining module |
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