CN103699001A - Method and system for realizing low-cost and high-precision timing through oven controlled crystal oscillator - Google Patents
Method and system for realizing low-cost and high-precision timing through oven controlled crystal oscillator Download PDFInfo
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- CN103699001A CN103699001A CN201210373445.5A CN201210373445A CN103699001A CN 103699001 A CN103699001 A CN 103699001A CN 201210373445 A CN201210373445 A CN 201210373445A CN 103699001 A CN103699001 A CN 103699001A
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Abstract
The invention discloses a method and a system for realizing low-cost and high-precision timing through an oven controlled crystal oscillator. The system comprises a GPS (global positioning system) receiver, an MCU single-chip microcomputer, a CPLD (complex programmable logic device) or a FPGA (field programmable gate array), and an oven controlled crystal oscillator, wherein the MCU single-chip microcomputer is connected with the GPS receiver to obtain GPS information, and that 1PPS signals output by the GPS receiver can be determined to be effective when the GPS receiver receivers at least 4 satellites; the CPLD or the FPGA receives the 1PPS signals of the GPS receiver, counts the frequency of the oven controlled crystal oscillator by taking the 1PPS signals as standard signals, and sends a statistical result to the MCU single-chip microcomputer when the statistical result reaches a specified threshold value; and the MCU single-chip microcomputer performs unitary nolinear regression equation calculation according to the statistical result, works out data required to be adjusted, and a voltage pin of the frequency of the oven controlled crystal oscillator is adjusted through output control voltage of the MCU single-chip microcomputer, so that the precision of the oven controlled crystal oscillator is locked on an atomic clock of the GPS, and the low-cost and high-precision timing is realized.
Description
Technical field
The present invention relates to the electronic equipment field of clocking, relate in particular to a kind of method and system that clock of low-cost and high-precision.
Background technology
The stochastic error of existing crystal oscillator clock signal is less, but has larger cumulative errors.And the pps pulse per second signal of GPS receiver output exists larger stochastic error, but there are not cumulative errors.Crystal oscillator has different request for utilizations and feature, is conventionally divided into following a few class: common crystals, temperature compensating crystal oscillator, VCXO, constant-temperature crystal oscillator etc.The grade common crystals of degree of accuracy is the poorest, and constant-temperature crystal oscillator is the highest, reaches
,
deng.Along with the fast development of wireless communication field, as the schemes such as micro-wave extension equipment of telecommunications aspect,
,
precision can not meet the demands, advance works teacher solve with rubidium clock, the precision of rubidium clock reaches
above, but this scheme cost compare is expensive, and Renminbi reaches 10,000 Renminbi even more than several ten thousand Renminbi, and the cost of constant-temperature crystal oscillator is the cost of hundreds of yuan.
Summary of the invention
The present invention, according to the feature of GPS clock signal and the complementation of constant-temperature crystal oscillator clock signal precision, estimates the statistical variance of GPS clock stochastic error and the cumulative errors of constant-temperature crystal oscillator; Constant-temperature crystal oscillator clock is revised in real time, produced high precision clock, and predicted revised clock accuracy.A kind of method and system that clock of utilizing constant-temperature crystal oscillator to realize low-cost and high-precision are provided.
Utilize constant-temperature crystal oscillator to realize the method that clocks of low-cost and high-precision, comprise step
1, system energising, completes initialization setting, and MCU single-chip microcomputer connects the information that GPS receiver obtains GPS, just can determine that the 1PPS signal of described GPS receiver output is effective when finding that GPS receiver receives that satellite reaches at least 4;
2, by CPLD (being CPLD) or field programmable gate array device (being FPGA), receive the 1PPS signal of GPS receiver, and as standard signal, frequency to constant-temperature crystal oscillator (being OCXO) is added up, statistics 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 monobasic Nonlinear regression equation formula according to described statistics, calculate the data that need adjustment, by the output of MCU single-chip microcomputer, control voltage and adjust voltage pin to the frequency of constant-temperature crystal oscillator, the precision of constant-temperature crystal oscillator is locked on the atomic clock of GPS, realize high precision and clock, precision exists
above.
Described step 3 also comprises by MCU single-chip microcomputer output control signal communicates by letter with GPS receiver, guarantees that the 1PPS signal of GPS receiver output is to lock onto on the atomic clock of GPS, and precision is
, by the computing of MCU single-chip microcomputer and CPLD, draw high-precision 1PPS output.
The described method that clocks also comprises the steps:
When GPS receiver provides normal frequency signal, every 2 hours, remember each 2 value PWM1 that adjust, PWM2; After gps data is lost, computing formula is as follows:
T=2*60/( PWM2 – PWM1)
The situation of change that can draw PWM after how many minutes, the ageing rate of controlling constant-temperature crystal oscillator by the adjustment of PWM changes, and makes its high precision output, until gps data is detected by MCU single-chip microcomputer again, returns again GPS and tames clock control.
The present invention also provides a kind of timing system that utilizes constant-temperature crystal oscillator to realize low-cost and high-precision, comprises GPS receiver, MCU single-chip microcomputer, CPLD or field programmable gate array device, constant-temperature crystal oscillator; Described MCU single-chip microcomputer connects respectively GPS receiver, CPLD or field programmable gate array device, constant-temperature crystal oscillator, and described GPS receiver connects CPLD or field programmable gate array device, constant-temperature crystal oscillator successively;
Described MCU single-chip microcomputer connects the information that GPS receiver obtains GPS, just can determine that the 1PPS signal of described GPS receiver output is effective when finding that GPS receiver receives that satellite reaches at least 4;
Described CPLD or field programmable gate array device receive the 1PPS signal of GPS receiver, and as standard signal, the frequency of constant-temperature crystal oscillator are added up, and statistics are sent to MCU single-chip microcomputer when counting on prescribed threshold;
Described MCU single-chip microcomputer carries out monobasic Nonlinear regression equation formula according to described statistics and calculates, calculate the data that need adjustment, by the output of MCU single-chip microcomputer, control voltage and adjust voltage pin to the frequency of constant-temperature crystal oscillator, the precision of constant-temperature crystal oscillator is locked on the atomic clock of GPS, realizes high precision and clock.
The present invention utilizes the devices such as constant-temperature crystal oscillator (OCXO), common single-chip microcomputer or MCU single-chip microcomputer, CPLD/FPGA, coordinates GPS or Big Dipper isochronon system, by method the simplest, least cost,
,
the constant-temperature crystal oscillator of magnitude (OCXO) is tamed into high precision output, directly locks onto on the atomic clock of GPS, and precision can reach
above, solved the problem that crystal oscillator self exists simultaneously: ageing rate, because constant-temperature crystal oscillator locks onto on atomic clock, the ageing rate of crystal oscillator will be controlled, frequency can be along with grow and change the conduction time of crystal oscillator.
Method of the present invention and timing system operating cost are low, by scientific and reasonable system, provide high accurate clock signal output, and precision can be
above, be successfully applied to the strange land synchronous recording of electrical power system transient change procedure.
Accompanying drawing explanation
Fig. 1 is that the constant-temperature crystal oscillator that utilizes that the embodiment of the present invention provides is realized the timing system structural representation of low-cost and high-precision.
Fig. 2 is the method that the clocks part schematic flow sheet that the embodiment of the present invention provides;
Fig. 3 is the OCXO crystal oscillator signal table that in the embodiment of the present invention, degree of accuracy is 10.0000005.
Embodiment
For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing, the present invention is described in further detail.
As shown in Figure 1, a kind of timing system that utilizes constant-temperature crystal oscillator to realize low-cost and high-precision that the embodiment of the present invention provides, comprises GPS receiver, MCU single-chip microcomputer, CPLD or field programmable gate array device, constant-temperature crystal oscillator; Described MCU single-chip microcomputer connects respectively GPS receiver, CPLD or field programmable gate array device, constant-temperature crystal oscillator, and described GPS receiver connects CPLD or field programmable gate array device, constant-temperature crystal oscillator successively; The method of clocking of the present invention is used in system of the present invention.
After system energising, described MCU single-chip microcomputer connects the information that GPS receiver obtains GPS, and MCU single-chip microcomputer is waited for constant-temperature crystal oscillator (OCXO) temperature stabilization and inquire about GPS receiver whether provide effective 1PPS signal; The 1PPS signal that just can determine described GPS receiver output when finding that GPS receiver receives that satellite reaches at least 4 is effective;
As shown in Figure 2, described CPLD (being CPLD) or field programmable gate array device (being FPGA) receive the 1PPS signal of GPS receiver, and as standard signal, frequency to constant-temperature crystal oscillator (OCXO) is added up, and statistics is sent to MCU single-chip microcomputer when counting on prescribed threshold; Such as prescribed threshold is 1000 times or 2000 times;
Described MCU single-chip microcomputer carries out monobasic Nonlinear regression equation formula according to described statistics and calculates, calculate the data that need adjustment, utilize One-place 2-th Order regression mathematical model to adjust rapidly the OCXO output frequency of 10MHz, and the output frequency of the 1PPS of CPLD or FPGA, by the PWM/DA pin output of MCU single-chip microcomputer, control voltage and adjust voltage pin to the frequency of constant-temperature crystal oscillator, the precision of constant-temperature crystal oscillator is locked on the atomic clock of GPS, realizes high precision and clock, precision can be
above.By MCU single-chip microcomputer, export control signal to GPS receiver simultaneously, the 1PPS signal accuracy of GPS receiver output is existed
above.
Specific algorithm is described as follows:
If the crystal oscillator of a nominal f0=10000000M, is f1=10000000.11000 by the frequency that the 53220A frequency counter of Agilent is tested, degree of accuracy is
(f0 - f1)/ f0=(10000000-10000000.11)/10000000= -1.1E-08（
）
From above formula, find out, perfect precision is
, but because be no matter MCU single-chip microcomputer or CPLD/FPGA, radix point data below all can not be processed, so the frequency of f1 in MCU single-chip microcomputer and CPLD/FPGA computing the inside, be the reading of 10000000(decimal not out), actual computation is as follows:
(f0 - f1)/ f0=(10000000-10000000)/10000000= -0E-07（
）
Can only be
precision, prior art will be accomplished so
, only way can frequency multiplication, because high frequency is higher to hardware requirement, has run counter to the scheme cheaply that the present invention advocates, so this frequency-doubling method cannot adopt.
The present invention improves in existing method, such as we have the degree of accuracy of an OCXO crystal oscillator, is 10.0000005, and from Fig. 3, we can see:
The frequency that 1 second, CPLD counted is 10000000, and radix point data are below removed;
The frequency of separately counting CPLD 2 seconds is 20000000(10000000+10000000) radix point data are below removed;
The frequency of supposing a crystal oscillator is 10000000.5000Hz by the frequency that oscillograph tests out p.s., because CPLD can only count integral part, will lose fraction part so, if extended the count cycle to 2 second, CPLD will be counted as so
F=f1+f2=10000000.5000+10000000.5000=2000001; Suppose that the count cycle is 100 seconds:
F= f1+f2+。。。+f100=10000000.5000+10000000.5000+。。。+10000000.5000=1000000050;
By that analogy, test when continuous 1000 seconds, CPLD's is counted as 10 000 000 500 so, these data can be processed by CPLD and MCU single-chip microcomputer, thereby can calculate by One-place 2-th Order regression equation the value of the PWM/DA needing, by adjusting the voltage-controlled voltage of OCXO, make its precision reach the value that the present invention wants.
The present invention program's way is to utilize the shake of eliminating GPS for 1000 seconds, find the frequency drift characteristic of OCXO, by the calculating of MCU single-chip microcomputer and CPLD/FPGA, find a control law that meets this crystal oscillator, make the precision of OCXO lock onto GPS upper, solved the expensive problem of bringing of rubidium clock, atomic clock.
In GPS receiver, there is certain error ε in output second clock and UCT.Investigate a certain second time series, the time error ε x of x second clock, ε x Normal Distribution:
εx～ N (0, б
2) (1)
The GPS receiver of different class, б numerical values recited is different.
Due to the stochastic error of the High Precision Crystal Oscillator stochastic error (clock stochastic error second that the crystal oscillator frequency division that is 10-9 as degree of stability produces is less than 1 n s) much smaller than GPS clock second, therefore do not consider the stochastic error of crystal oscillator clock second.Only consider the frequency departure of crystal oscillator and the linear drift of frequency, the time error μ (x) that is produced x second clock of second seasonal effect in time series by crystal oscillator frequency division can be expressed as:
μ(x ) = a + bx + cx
2 (2)
In formula: a is a second seasonal effect in time series initial error; B is for considering the error coefficient of frequency departure; C is for considering the error coefficient of frequency linearity drift.
The deviation being obtained between crystal oscillator frequency division clock second (being called for short crystal oscillator clock second) and GPS clock second by formula (1) and formula (2) is:
YX=a+bx+c x
2+ε
X （x ∈ n ） (3)
The deviation of crystal oscillator clock second and GPS clock second can be measured, and establish measurement result sequence Y and be expressed as: Y 1, and Y 2 ..., Y x ..., Y n.Time series by Y estimates regression coefficient a by the One-place 2-th Order regression analysis model shown in formula (3), b, c, x of crystal oscillator output second clock and UCT between error estimate μ (x) be:
μ (x ) = a+ bx + cx
2 (4)
According to error estimate μ (x), the frequency of crystal oscillator is compensated, obtain high-precision crystal oscillator frequency and produce high precision clock.
The method that clocks of the present invention also comprises precision and the punctual step that keeps after OCXO losing lock:
As everyone knows, the frequency of crystal oscillator, also can change along with the aging of time changing except meeting variation with temperature.This method is because the frequency of OCXO is the second on signal that locks onto GPS; using the 1PPS of GPS as timing reference input; the variation of adjusting frequency by PWM mode; can say the aging problem that do not exist; but after gps data is lost; 1PPS timing reference input also will be lost; tame and will lose meaning; OCXO will be with ageing rate free oscillation so; in order to guarantee that gps clock signal continues to provide high-precision frequency signal; when providing normal frequency signal, GPS remembered each 2 value PWM1 that adjust every 2 hours, PWM2; After gps data is lost, computing formula is as follows:
T=2*60/( PWM2 – PWM1);
The variation that can draw PWM after how many minutes, the ageing rate of controlling OCXO by the adjustment of PWM changes, and makes its high precision output, until GPS is detected by MCU single-chip microcomputer again, returns again GPS and tames clock control.
The above is the preferred embodiment of the present invention; certainly can not limit with this interest field of the present invention; for those skilled in the art; under the premise without departing from the principles of the invention; can also make some improvement and change, these improvement and change are also considered as protection scope of the present invention.
Claims (5)
1. utilize constant-temperature crystal oscillator to realize the method that clocks of low-cost and high-precision, comprise step
One, system energising, completes initialization setting, and MCU single-chip microcomputer connects the information that GPS receiver obtains GPS, just can determine that the 1PPS signal of described GPS receiver output is effective when finding that GPS receiver receives that satellite reaches at least 4;
Two, by CPLD or field programmable gate array device, receive the 1PPS signal of GPS receiver, and as standard signal, frequency to constant-temperature crystal oscillator is added up, and statistics is sent to MCU single-chip microcomputer when counting on prescribed threshold;
Three, MCU single-chip microcomputer carries out the calculating of monobasic Nonlinear regression equation formula according to described statistics, calculate the data that need adjustment, by the output of MCU single-chip microcomputer, control voltage and adjust voltage pin to the frequency of constant-temperature crystal oscillator, the precision of constant-temperature crystal oscillator is locked on the atomic clock of GPS, realizes high precision and clock.
2. the method that clocks according to claim 1, is characterized in that, described step 3 also comprises
By MCU single-chip microcomputer output control signal, communicate by letter with GPS receiver, guarantee that the 1PPS signal of GPS receiver output is to lock onto on the atomic clock of GPS, precision is
, by the computing of MCU single-chip microcomputer and CPLD, draw high-precision 1PPS output.
3. the method that clocks according to claim 1, is characterized in that, also comprises the steps:
When GPS receiver provides normal frequency signal, every 2 hours, remember each 2 value PWM1 that adjust, PWM2; After gps data is lost, computing formula is as follows:
T=2*60/( PWM2 – PWM1)
The situation of change that can draw PWM after how many minutes, the ageing rate of controlling constant-temperature crystal oscillator by the adjustment of PWM changes, and makes its high precision output, until gps data is detected by MCU single-chip microcomputer again, returns again GPS and tames clock control.
4. the method that clocks according to claim 1, is characterized in that, the prescribed threshold in described step 2 is 1000 times or 2000 times.
5. utilize constant-temperature crystal oscillator to realize a timing system for low-cost and high-precision, it is characterized in that, comprise GPS receiver, MCU single-chip microcomputer, CPLD or field programmable gate array device, constant-temperature crystal oscillator; Described MCU single-chip microcomputer connects respectively GPS receiver, CPLD or field programmable gate array device, constant-temperature crystal oscillator, and described GPS receiver connects CPLD or field programmable gate array device, constant-temperature crystal oscillator successively;
Described MCU single-chip microcomputer connects the information that GPS receiver obtains GPS, just can determine that the 1PPS signal of described GPS receiver output is effective when finding that GPS receiver receives that satellite reaches at least 4;
Described CPLD or field programmable gate array device receive the 1PPS signal of GPS receiver, and as standard signal, the frequency of constant-temperature crystal oscillator are added up, and statistics are sent to MCU single-chip microcomputer when counting on prescribed threshold;
Described MCU single-chip microcomputer carries out monobasic Nonlinear regression equation formula according to described statistics and calculates, calculate the data that need adjustment, by the output of MCU single-chip microcomputer, control voltage and adjust voltage pin to the frequency of constant-temperature crystal oscillator, the precision of constant-temperature crystal oscillator is locked on the atomic clock of GPS, realizes high precision and clock.
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| CN105824232A (en) * | 2016-05-25 | 2016-08-03 | 北京理工大学 | Portable self-calibration time service device and time service method |
| CN105867107A (en) * | 2016-04-08 | 2016-08-17 | 唐道勇 | Low-power high-precision time service system |
| 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 |
| CN107831647A (en) * | 2016-09-15 | 2018-03-23 | 卡西欧计算机株式会社 | Positioner, electronic watch, position control method and storage medium |
| CN108599758A (en) * | 2018-02-10 | 2018-09-28 | 国网河南省电力公司郑州供电公司 | The algorithm and device of high-precision trigger pulse are generated based on GPS |
| CN108667546A (en) * | 2018-04-20 | 2018-10-16 | 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 |
| CN109597297A (en) * | 2018-12-11 | 2019-04-09 | 烟台持久钟表有限公司 | A kind of crystal oscillator compensation method and device |
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| CN107831647A (en) * | 2016-09-15 | 2018-03-23 | 卡西欧计算机株式会社 | Positioner, electronic watch, position control method and storage medium |
| CN107831647B (en) * | 2016-09-15 | 2019-12-13 | 卡西欧计算机株式会社 | Positioning device, electronic timepiece, positioning control method, and storage medium |
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| CN108599758A (en) * | 2018-02-10 | 2018-09-28 | 国网河南省电力公司郑州供电公司 | The algorithm and device of high-precision trigger pulse are generated based on GPS |
| 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 |
| CN108667546A (en) * | 2018-04-20 | 2018-10-16 | 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 |
| 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 |
| CN109597297A (en) * | 2018-12-11 | 2019-04-09 | 烟台持久钟表有限公司 | A kind of crystal oscillator compensation method and device |
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