CN103699001B - Utilize clocking method and system that constant-temperature crystal oscillator realizes - Google Patents
Utilize clocking method and system that constant-temperature crystal oscillator realizes Download PDFInfo
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- CN103699001B CN103699001B CN201210373445.5A CN201210373445A CN103699001B CN 103699001 B CN103699001 B CN 103699001B CN 201210373445 A CN201210373445 A CN 201210373445A CN 103699001 B CN103699001 B CN 103699001B
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Abstract
The invention discloses a kind of clocking method utilizing constant-temperature crystal oscillator to realize and system, system includes GPS, MCU single-chip microcomputer, CPLD or FPGA, constant-temperature crystal oscillator；Described MCU single-chip microcomputer connects GPS and obtains the information of GPS, is assured that the 1PPS signal that described GPS exports is effective when finding that GPS receives when satellite reaches at least 4；Described CPLD or FPGA receives the 1PPS signal of GPS, and as standard signal, adds up the frequency of constant-temperature crystal oscillator, and statistical result is sent to MCU single-chip microcomputer when counting on prescribed threshold；Described MCU single-chip microcomputer carries out unitary Nonlinear regression equation formula according to described statistical result and calculates, calculate the data needing to adjust, control voltage by the output of MCU single-chip microcomputer and adjust voltage foot to the frequency of constant-temperature crystal oscillator, the precision making constant-temperature crystal oscillator is locked on the atomic clock of GPS, it is achieved timing.
Description
Technical field
The present invention relates to electronic equipment clock field, particularly relate to a kind of clocking method and system.
Background technology
The random error of existing crystal oscillator clock signal is less, but there are bigger cumulative errors.And GPS receiver
There is bigger random error in the pps pulse per second signal of machine output, but there are not cumulative errors.Crystal oscillator has difference to make
With requiring and feature, it is generally divided into following a few class: common crystals, temperature compensating crystal oscillator, VCXO, constant temperature are brilliant
Shake.The grade common crystals of degree of accuracy is worst, and constant-temperature crystal oscillator is the highest, reaches 10-8、10-9Deng.Along with wireless
The fast development of the communications field, the scheme such as micro-wave extension equipment in terms of telecommunications, 10-8、10-9Precision
Through not meeting requirement, advance works teacher solve with rubidium clock, and the precision of rubidium clock reaches 10-10Above, but should
Scheme cost is somewhat expensive, and RMB reaches more than 10,000 RMB even several ten thousand RMB, and the one-tenth of constant-temperature crystal oscillator
This is the cost of hundreds of yuan.
Summary of the invention
The present invention, according to the feature of GPS clock signal with the complementation of constant-temperature crystal oscillator clock signal precision, estimates
The statistical variance of gps clock random error and the cumulative errors of constant-temperature crystal oscillator；Constant-temperature crystal oscillator clock is carried out reality
Shi Xiuzheng, produces high precision clock, and predicts revised clock accuracy.Providing one utilizes constant temperature brilliant
The clocking method of oscillation body device realization and system.
A kind of clocking method utilizing constant-temperature crystal oscillator to realize, including step
1, system energization, completes Initialize installation, and MCU single-chip microcomputer connects GPS and obtains GPS
Information, when finding that GPS receives when satellite reaches at least 4 and is assured that described GPS receiver
The 1PPS signal of machine output is effective；
2, by CPLD (i.e. CPLD) or field programmable gate array device (i.e. FPGA)
Receive the 1PPS signal of GPS, and as standard signal, to constant-temperature crystal oscillator (i.e.
OCXO) frequency is added up, and statistical result is sent to MCU single-chip microcomputer when counting on prescribed threshold,
Such as prescribed threshold is 1000 times or 2000 times；
3, MCU single-chip microcomputer carries out the calculating of unitary Nonlinear regression equation formula according to described statistical result, calculates
Go out to need the data adjusted, control voltage by the output of MCU single-chip microcomputer and adjust to the frequency of constant-temperature crystal oscillator
Whole voltage foot, makes the precision of constant-temperature crystal oscillator be locked on the atomic clock of GPS, it is achieved high-precision timing,
Precision is 10-12Above.
Described step 3 also includes by MCU single-chip microcomputer output control signal and GPS communication, really
The 1PPS signal protecting GPS output is locked out on the atomic clock of GPS, and precision is 10-12, pass through
MCU single-chip microcomputer and the computing of CPLD, show that high-precision 1PPS exports.
The described method that clocks also comprises the steps:
GPS provides normal frequency signal when, remembered 2 every time adjusted every 2 hours
Individual value PWM1, PWM2；After gps data is lost, computing formula is as follows:
T=2*60/ (PWM2 PWM1)
The situation of change of PWM after can drawing how many minutes, controls constant temperature by the adjustment of PWM brilliant
The ageing rate change of oscillation body device so that it is high accuracy output, until gps data is again by MCU single-chip microcomputer
Detect, return again GPS and tame clock control.
The present invention also provides for a kind of timekeeping system utilizing constant-temperature crystal oscillator to realize, including GPS receiver
Machine, MCU single-chip microcomputer, CPLD or field programmable gate array device, constant temperature crystal vibration
Device；Described MCU single-chip microcomputer connects GPS, CPLD or scene respectively and can compile
Journey gate array device, constant-temperature crystal oscillator, described GPS is sequentially connected with CPLD
Or field programmable gate array device, constant-temperature crystal oscillator；
Described MCU single-chip microcomputer connects GPS and obtains the information of GPS, when finding GPS
Receive satellite to reach when at least 4, to be assured that the 1PPS signal that described GPS exports is effective；
Described CPLD or field programmable gate array device receive the 1PPS of GPS
Signal, and as standard signal, the frequency of constant-temperature crystal oscillator is added up, when counting on regulation
During threshold values, statistical result is sent to MCU single-chip microcomputer；
Described MCU single-chip microcomputer carries out unitary Nonlinear regression equation formula according to described statistical result and calculates, meter
Calculate the data needing to adjust, control voltage to the frequency of constant-temperature crystal oscillator by the output of MCU single-chip microcomputer
Adjust voltage foot, make the precision of constant-temperature crystal oscillator be locked on the atomic clock of GPS, it is achieved high accuracy meter
Time.
The present invention utilizes constant-temperature crystal oscillator (OCXO), common single-chip microcomputer or MCU single-chip microcomputer, CPLD/FPGA
Deng device, coordinate GPS or Big Dipper isochronon system, by the simplest, the method for least cost, 10-8、
10-9The constant-temperature crystal oscillator (OCXO) of magnitude tames into high accuracy output, is directly locked on the atomic clock of GPS,
Precision is up to 10-12Above, the problem simultaneously solving crystal oscillator self existence: ageing rate, because constant-temperature crystal oscillator
Locking onto on atomic clock, the ageing rate of crystal oscillator will be controlled, and frequency will not be long along with the conduction time of crystal oscillator
And change.
Method and the timing system operating cost of the present invention are low, are designed by scientific and reasonable system, it is provided that high
Accuracy clock signals exports, and precision can be 10-12Above, it has been applied successfully to electrical power system transient changed
The strange land synchronous recording of journey.
Accompanying drawing explanation
Fig. 1 is the timekeeping system structural representation utilizing constant-temperature crystal oscillator to realize that the embodiment of the present invention provides
Figure.
Fig. 2 is the clocking method part schematic flow sheet that the embodiment of the present invention provides.
Fig. 3 is that in the embodiment of the present invention, degree of accuracy is an OCXO crystal oscillator signal table of 10.0000005.
Detailed description of the invention
For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing to the present invention
It is described in further detail.
As it is shown in figure 1, a kind of timing system utilizing constant-temperature crystal oscillator to realize that the embodiment of the present invention provides
System, including GPS, MCU single-chip microcomputer, CPLD or field programmable gate array
Device, constant-temperature crystal oscillator；Described MCU single-chip microcomputer connects GPS respectively, complex programmable is patrolled
Collecting device or field programmable gate array device, constant-temperature crystal oscillator, described GPS is sequentially connected with multiple
Miscellaneous PLD or field programmable gate array device, constant-temperature crystal oscillator；The side of clocking of the present invention
Method is used in a system of the invention.
After system energization, described MCU single-chip microcomputer connects GPS and obtains the information of GPS, MCU
Single-chip microcomputer waits constant-temperature crystal oscillator (OCXO) temperature stabilization and inquires about whether GPS is provided with
The 1PPS signal of effect；Described in discovery GPS receives and is assured that when satellite reaches at least 4
The 1PPS signal of GPS output is effective；
As in figure 2 it is shown, described CPLD (i.e. CPLD) or field programmable gate array
Device (i.e. FPGA) receives the 1PPS signal of GPS, and as standard signal, to constant temperature crystal
The frequency of agitator (OCXO) is added up, and when counting on prescribed threshold, statistical result is sent to MCU
Single-chip microcomputer；Such as prescribed threshold is 1000 times or 2000 times；
Described MCU single-chip microcomputer carries out unitary Nonlinear regression equation formula according to described statistical result and calculates, meter
Calculate the data needing to adjust, utilize One-place 2-th Order regression mathematical model to adjust rapidly the OCXO of 10MHz defeated
Go out frequency, and the output frequency of the 1PPS of CPLD or FPGA, by the PWM/DA of MCU single-chip microcomputer
Foot output controls voltage and adjusts voltage foot to the frequency of constant-temperature crystal oscillator, makes the essence of constant-temperature crystal oscillator
Degree is locked on the atomic clock of GPS, it is achieved high-precision timing, precision can be 10-12Above.Pass through simultaneously
MCU single-chip microcomputer output control signal, to GPS, makes the 1PPS signal accuracy that GPS exports
10-12Above.
Specific algorithm is described as follows:
If the crystal oscillator of a nominal f0=10000000M, survey with the 53220A frequency counter of Agilent
The frequency of examination is f1=10000000.11000, and degree of accuracy is
(f0-f1)/f0=(10000000-10000000.11)/10000000=-1.1E-08 (10-8)
Finding out from above formula, perfect precision is 10-8, but it is because either that MCU single-chip microcomputer is still
CPLD/FPGA, arithmetic point data below all can not process, so the frequency of f1 at MCU single-chip microcomputer and
Being 10000000 (arithmetic point is read the most out) inside CPLD/FPGA computing, Practical Calculation is as follows:
(f0-f1)/f0=(10000000-10000000)/10000000=-0E-07 (10-7)
Can only be 10-7Precision, then prior art to accomplish 10-12, only way can be with frequency multiplication, because high frequency pair
Hardware requirement is higher, has run counter to the scheme of the low cost that the present invention advocates, so this frequency-doubling method cannot
Use.
The present invention improves in existing method, and such as we have the degree of accuracy of an OCXO crystal oscillator to be
10.0000005, from Fig. 3 it may be seen that:
The frequency of 1 second CPLD meter is 10000000, and arithmetic point data below are removed；
After the frequency separately counting CPLD in 2 seconds is 20000000 (10000000+10000000) arithmetic point
The data in face are removed；
Assume that the frequency oscillograph of a crystal oscillator tests out the frequency of each second and is
10000000.5000Hz, because CPLD can only count integer part, then will lose fractional part, if prolonged
Grow the counting cycle to 2 seconds, then CPLD will be counted as
F=f1+f2=10000000.5000+10000000.5000=2000001；Assume that the counting cycle is 100 seconds:
F=f1+f2+...+ f100=10000000.5000+10000000.5000+...
+ 10000000.5000=1000000050；
By that analogy, when the test of continuous 1000 seconds, then CPLD is counted as 10 000 000 500,
These data can be processed by CPLD and MCU single-chip microcomputer, such that it is able to by One-place 2-th Order regression equation
Calculate the value of the PWM/DA of needs, make its precision reach the present invention by adjusting the voltage-controlled voltage of OCXO
The value wanted.
The way of the present invention program is the shake utilizing 1000 seconds to eliminate GPS, finds the frequency of OCXO
Drift characteristic, by the calculating of MCU single-chip microcomputer Yu CPLD/FPGA, finds a control meeting this crystal oscillator
Rule processed, makes the precision of OCXO lock onto on GPS, solves the high cost brought of rubidium clock, atomic clock
Problem.
In the gps receiver, there is certain error ∈ with UCT in output second clock.When investigating a certain second
Between sequence, the time error ∈ of x-th second clockx, x Normal Distribution:
∈x～N (0, б2) (1)
The GPS of different class, б numerical values recited is different.
Owing to the random error of High Precision Crystal Oscillator is much smaller than the random error of GPS second clock (as degree of stability is
The second clock random error that the crystal oscillation fractional frequency of 10-9 produces is less than 1ns), the most do not consider crystal oscillator second clock
Random error.Only consider the frequency departure of crystal oscillator and the linear drift of frequency, crystal oscillation fractional frequency produce time second sequence
Time error μ (x) of the x-th second clock of row can be expressed as:
μ (x)=a+bx+cx2 (2)
In formula: a is second seasonal effect in time series initial error；B is the error coefficient considering frequency departure；C is for examining
Consider the error coefficient of frequency linearity drift.
By formula (1) and formula (2) crystal oscillation fractional frequency second clock (being called for short crystal oscillator second clock) and GPS second clock it
Between deviation be:
YX=a+bx+c x2+∈x x∈n (3)
The deviation of crystal oscillator second clock and GPS second clock can be measured, if measurement result sequence Y table
It is shown as: Y1,Y2,…,Yx,…,Yn.By the One-place 2-th Order regression analysis as shown in formula (3) of the time series of Y
Model estimates regression coefficient a, b, c, then the error between x-th second clock and the UCT of crystal oscillator output is estimated
Evaluation μ (x) is:
μ (x)=a+bx+cx2 (4)
According to error estimate μ (x), the frequency of crystal oscillator is compensated, obtain high-precision crystal oscillator frequency with
And generation high precision clock.
The method that clocks of the present invention also includes the precision after OCXO losing lock and the punctual step that keeps:
It is known that in addition to the frequency of crystal oscillator changes except meeting variation with temperature, also can be over time
Aging and change.This method is because the frequency of OCXO and is locked out on the second signal of GPS, with GPS
1PPS as timing reference input, adjusted the change of frequency by PWM mode, it may be said that do not exist aging
Problem, but when gps data lose after, 1PPS timing reference input also will lose, tame will lose meaning,
So OCXO will be with ageing rate free oscillation, in order to ensure that GPS clock signal continues to provide high-precision frequency
Rate signal, remembered 2 values every time adjusted GPS provides normal frequency signal when every 2 hours
PWM1,PWM2；After gps data is lost, computing formula is as follows:
T=2*60/ (PWM2 PWM1)；
After can drawing how many minutes, the change of PWM, controls the old of OCXO by the adjustment of PWM
Rate changes so that it is high accuracy output, until GPS is detected by MCU single-chip microcomputer again, returns again GPS
Tame clock control.
The above is the preferred embodiment of the present invention, certainly can not limit the power of the present invention with this
Profit scope, for those skilled in the art, under the premise without departing from the principles of the invention,
Can also make some improvement and variation, these improve and variation is also considered as protection scope of the present invention.
Claims (4)
1. utilize the clocking method that constant-temperature crystal oscillator realizes, including step
One, system energization, completes Initialize installation, and MCU single-chip microcomputer connects GPS and obtains GPS
Information, when finding that GPS receives when satellite reaches at least 4 and is assured that described GPS receiver
The 1PPS signal of machine output is effective；
Two, GPS is received by CPLD or field programmable gate array device
1PPS signal, and as standard signal, the frequency of constant-temperature crystal oscillator is added up, when counting on
During prescribed threshold, statistical result is sent to MCU single-chip microcomputer；
Three, MCU single-chip microcomputer carries out the calculating of unitary Nonlinear regression equation formula, meter according to described statistical result
Calculate the data needing to adjust, control voltage to the frequency of constant-temperature crystal oscillator by the output of MCU single-chip microcomputer
Adjust voltage foot, make the precision of constant-temperature crystal oscillator be locked on the atomic clock of GPS, it is achieved high accuracy meter
Time；
GPS provides normal frequency signal when, remembered 2 every time adjusted every 2 hours
Individual value PWM1, PWM2；After gps data is lost, computing formula is as follows:
T=2*60/ (PWM2 PWM1)
The situation of change of PWM after can drawing how many minutes, controls constant temperature by the adjustment of PWM brilliant
The ageing rate change of oscillation body device so that it is high accuracy output, until gps data is again by MCU single-chip microcomputer
Detect, return again GPS and tame clock control.
Clocking method the most according to claim 1, it is characterised in that described step 3 also includes
By MCU single-chip microcomputer output control signal and GPS communication, it is ensured that GPS is defeated
The 1PPS signal gone out is locked out on the atomic clock of GPS, and precision is 10-12, by MCU single-chip microcomputer with multiple
The computing of miscellaneous PLD, show that high-precision 1PPS exports.
Clocking method the most according to claim 1, it is characterised in that the regulation valve in described step 2
Value is 1000 times or 2000 times.
4. the timekeeping system using claim 1 method, it is characterised in that include GPS,
MCU single-chip microcomputer, CPLD or field programmable gate array device, constant-temperature crystal oscillator；
Described MCU single-chip microcomputer connects GPS, CPLD or field programmable gate respectively
Array device, constant-temperature crystal oscillator, described GPS is sequentially connected with CPLD or existing
Field programmable gate array device, constant-temperature crystal oscillator；
Described MCU single-chip microcomputer connects GPS and obtains the information of GPS, when finding GPS
Receive satellite to reach when at least 4, to be assured that the 1PPS signal that described GPS exports is effective；
Described CPLD or field programmable gate array device receive the 1PPS of GPS
Signal, and as standard signal, the frequency of constant-temperature crystal oscillator is added up, when counting on regulation
During threshold values, statistical result is sent to MCU single-chip microcomputer；
Described MCU single-chip microcomputer carries out unitary Nonlinear regression equation formula according to described statistical result and calculates, meter
Calculate the data needing to adjust, control voltage to the frequency of constant-temperature crystal oscillator by the output of MCU single-chip microcomputer
Adjust voltage foot, make the precision of constant-temperature crystal oscillator be locked on the atomic clock of GPS, it is achieved high accuracy meter
Time.
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| CN105824232B (en) * | 2016-05-25 | 2018-09-25 | 北京理工大学 | A kind of portable self calibration time service device and time service method |
| JP6772700B2 (en) * | 2016-09-15 | 2020-10-21 | カシオ計算機株式会社 | Positioning equipment, electronic clocks, positioning control methods, and programs |
| CN107229217A (en) * | 2017-06-01 | 2017-10-03 | 中船航海科技有限责任公司 | A kind of time synchronism apparatus and its synchronous method |
| CN108599758B (en) * | 2018-02-10 | 2022-11-22 | 国网河南省电力公司郑州供电公司 | Algorithm and device for generating high-precision trigger pulse based on GPS |
| CN108667546B (en) * | 2018-04-20 | 2019-09-10 | 武汉虹信通信技术有限责任公司 | A kind of soft-lock phase method moving fuzzy self-adaption in small base station equipment |
| CN109597297B (en) * | 2018-12-11 | 2020-09-08 | 烟台持久钟表有限公司 | Crystal oscillator compensation method and device |
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