CN102916743A - Time delay asymmetric difference accurate measurement method - Google Patents

Abstract

The invention discloses a time delay asymmetric difference accurate measurement method which performs analysis on the asymmetric difference accurate measurement method and provides a solution. According to the solution, no additional fine measuring instruments and meters are added, and only an HTF-BITS (high-precision time frequency-background intelligent transfer service) apparatus adopts a periodic bidirectional three-dimensional time coordinate comparison algorithm to perform automatic comparison, automatic calibration and asymmetric difference automatic balanced compensation of data links. Thus, an integrated three-stage synchronous network fused with extra-high-precision, ultra-high-precision and high-precision time frequencies (<=+/-1ns, <=+/-10ns and <=+/-20ns) throughout the country is realized. Through the popularization of the method, the extra-high-precision time frequency reference of 1-second difference per 200 million years can be transferred to any place in the world through a ground (underground) optical network, thereby providing required extra-high-precision time reference for various communication networks.

Description

The method that the asymmetric difference of a kind of time delay accurately measures

Technical field

The invention belongs to optical communication transmission network network field, relate to the method that the asymmetric difference of time delay accurately measures in a kind of optical communication transmission network network.

Background technology

It net refers to that the temporal frequency synchro system (being called for short a day net) in day space comprises two large classes: a class is GPS, GLONAIS, the Big Dipper and galileo satellite navigation system.In general add several quiet 33 in the whole world that add high-speed cruising of getting on the right track on the equator and just formed sky satellite navigation temporal frequency Synchronization Network.To the year two thousand twenty GPS three generations time service precision≤1ns; Positioning accuracy≤0.2 ~ 0.5 meter;

Another kind of is ACES(space atomic clock group).ACES came into effect to be transmitted into the upper satellite atomic clock group of future generation of international space station AIPHA in 2003, was by high frequency stability of the U.S., Russia, Japan, Europe and Canadian Joint Implementation and cesium-beam atomic clock or the hydrogen atomic clock of high accuracy.Set up timing experiment chamber, high performance space at the AIPHA station.ACES is an important temporal frequency research platform, if ground atomic clock and it compare, comparison accuracy is than high two orders of magnitude of GPS.The development of ACES atomic clock technology is beneficial to the development of follow-on Global Navigation Satellite System (GNSS).

It net temporal frequency precision is very high, the whole world Anywhere any time the receiver of any reception sky temporal frequency net Satellite than the time service precision and frequency stability and the accuracy (1 grade of clock level) that are easier to be better than GPS.

But a day net also has a lot of shortcomings simultaneously.Its maximum shortcoming is unsteadiness: the interference that is subject on the one hand atmospheric environment, the pulse of sun nuclear-magnetism etc.; Artificial disturbance or people are the damage of smashing of closing interruption or war on the other hand, must have antenna feeding system to collect mail from air interface in addition and cease and could work.

Earth mat: China is just building up the underground optical communication transmission network network of Eight Verticals and Eight Horizontals at the end of last century, has been to consist of the underground communication net that extends in all direction by three large telecommunications business companies and national defence private network, power communication private network etc. now.Therefore we will be underground be that supporting body establishment temporal frequency Synchronization Network is called earth mat by the optical communication transmission network network.

Not relying on GPS Big Dipper sky satellite navigation system to realize that underground optical communication transmission system is transmitted and the core in the synchronous split-second precision of slave station source, is to the propagation delay time of optical transmission communication network and the technology that accurately measures of asymmetric difference thereof.

The relevant split-second precision measuring instrument of current usefulness can measure certain precision and right title difference to optical communication transmission system time delay to carry out the once benefit of passive type and tastes.Because optical communication transmission network network aspect facts have proved that the propagation delay time of optical transmission communication network and asymmetric difference thereof are the numbers of a change at random, that is to say and must regularly measure and proofread and correct.

In the optical communication transmission network network, use two-way time code stream correlation technique to the reliable and stable operation of whole network, detect in advance the marginal performance of whole network, send marginal performance alarm, thereby ensure the low interruption rate of communication network.

Summary of the invention

The objective of the invention is to set up (≤± 1ns ,≤± 10ns ,≤± integrated three grades of synchronizing networks that national super high precision 20ns), superhigh precision, split-second precision frequency merge.By the popularization of the method, can the super high precision temporal frequency benchmark that differ from 200,000,000 years 1 second be delivered under the sun by ground (underground) optical-fiber network, for the various types of communication network provides required super high precision time reference.

The objective of the invention is to solve by the following technical programs:

The method that the asymmetric difference of a kind of time delay accurately measures:

1) set up the optical communication transmission network network in split-second precision frequency BITS equipment, lead-stand and pass through optical communication transmission network network passing time reference signal between the synchronizer, main website and slave station time synchronized adopt the two-way mode of comparing;

2) time interval deviation of the following calculated with mathematical model MS master-slave synchronizer of employing:

In 1. formula, Es represents principal and subordinate's relative time spacing bias;

E0 represents principal and subordinate's initial time spacing bias;

The remaining time drift error of expression principal and subordinate Frequency Synchronization after using frequency and phase discrimination zero passage detection Phase Lock Technique;

Δ T _Xy(t) represent asymmetric difference, i.e. Δ T _Xy(t)=| T _x(t)-T _y(t) |, T wherein _x(t) expression is passed through the optical communication transmission network network to the time interval value between the slave station clock synchronization device signal, T by the signal of main website clock synchronization device transmission _y(t) signal process optical communication transmission network network to the main website clock synchronization device of expression slave station clock synchronization device transmission receives the time interval value between the signal;

The randomized jitter noise that the expression optical-fiber network is introduced when the passing time benchmark;

1. first three items is finished by long-distance remote control loose coupling frequency and phase discrimination zero passage detection Phase Lock Technique in the formula, and error is controlled at ± 5X10 ^-14/ day;

3) adopt the three-dimensional time coordinate to accurately measure Δ T _Xy(t): in main website, measure loopback cycle C value, loopback cycle C value is: C=T _Xi(t)+T _Yi(t), i represents bit quantity, chooses nominal period C according to C values different in the table 1 _MarkValue,

Table 1

Loopback cycle C

<125us

<250us

<1ms

...

<10ms

<100ms

...

Nominal period C Mark

125us

250us

1ms

...

10ms

100ms

...

[0025]Work as T _Xi(t)=T _Yi(t), △ T _Xiyi(t) during ≈ 0, realize that the propagation delay time of the two-way comparison transmission of master station and follow station and back equates;

Work as T _Xi(t)＞T _Yi(t) time,

Work as T _Xi(t)＜T _Yi(t) time,

With △ T _Xiyi(t) precisely measure, realize that the MS master-slave relative time is synchronous;

，

The two-way comparison mode of further above-mentioned employing is two-way time code stream comparison;

Further realize the synchronous precision of MS master-slave relative time be≤± 20ns ,≤± 10ns ,≤± 5ns ,≤± 2ns or≤± 1ns; Further adopt the low phase noise platform of split-second precision frequency BITS equipment, improve so that measure precision

Doubly, wherein N represents the number of times of duplicate measurements in 1 second, the time of τ observation test.

The present invention is directed to asymmetric difference △ T _Xy(t) solution is analyzed and proposed to the method for accurately measuring, this solution does not increase extra precision measuring instrument instruments and meters, only by HTF-BITS(split-second precision frequency BITS equipment) adopt regular two-way three-dimensional time coordinate alignment algorithm, carry out the automatic equalization compensation of automatic comparison, automatic calibration and the asymmetric difference of data link.

Description of drawings

Fig. 1 a-1b is three-dimensional coordinate C _Mark=1ms instrumentation plan;

Fig. 2 is the two-way timing code flow data of 1000km link comparison schematic diagram;

Fig. 3 is for taking in Chengdu as the schematic diagram of example.

Embodiment

Below in conjunction with accompanying drawing the present invention is done and to describe in further detail:

The method that the asymmetric difference of a kind of time delay accurately measures:

1) set up the optical communication transmission network network in split-second precision frequency BITS equipment, lead-stand and pass through optical communication transmission network network passing time reference signal between the synchronizer, main website and slave station time synchronized adopt the two-way mode of comparing;

2) time interval deviation of the following calculated with mathematical model MS master-slave synchronizer of employing:

In 1. formula, Es represents principal and subordinate's relative time spacing bias;

E0 represents principal and subordinate's initial time spacing bias;

The remaining time drift error of expression principal and subordinate Frequency Synchronization after using frequency and phase discrimination zero passage detection Phase Lock Technique;

Δ T _Xy(t) represent asymmetric difference, i.e. Δ T _Xy(t)=| T _x(t)-T _y(t) |, T wherein _x(t) expression is passed through the optical communication transmission network network to the time interval value between the slave station clock synchronization device signal, T by the signal of main website clock synchronization device transmission _y(t) signal process optical communication transmission network network to the main website clock synchronization device of expression slave station clock synchronization device transmission receives the time interval value between the signal;

The randomized jitter noise that the expression optical-fiber network is introduced when the passing time benchmark;

1. first three items is finished by long-distance remote control loose coupling frequency and phase discrimination zero passage detection Phase Lock Technique in the formula, and error is controlled at ± 5X10 ^-14/ day;

The three-dimensional time coordinate accurately measures T _Xi(t), T _Yi(t), reach Principle.

In the two-way timing code flow data comparison

C=T _xi(t)+T _yi(t) ②

In the measurement of the loopback C of main website (MASTER) value shown in Fig. 1 a, Fig. 1 b.

In a pair of Optical Fiber Transmission, Frequency Synchronization is better than 1X10 ^-11Level is worked as F _Main=F _From, namely the time interval measurement at two ends is identical.

C _{Ring is main}=C _{Ring from}=T _Xi(t)+T _Yi(t) 3.

According to the IEEE1588one-step principle main website code stream output panel of two-way time take main website 1PPS initial point be the 1PPS rising edge as starting point, send T to slave station _Xi(t) code stream is realized two-way contrast the remote measurement time interval.

Choose C according to different loopback C values _MarkValue, as shown in table 1:

Table 1:C _MarkValue converts with loopback C value

C _MarkCycle

The frequency time code stream is exactly the nominal time interval code stream that main website sends, and its effect has: (with C＜1ms, C _Mark=1ms, the 50Km optical communication is end-to-end to be example)

Use C _Mark=1ms, namely

With the 1PPS of main website (MASTER) initial point with The alignment of some rising edges after (error≤1ns, and formed the 1000PPS initial point of the five equilibrium of 1,000 1000PPS, and take this 1000PPS initial point as starting point, sending to slave station (SLAVER).

MS master-slave station light transmission delay Txi (t), 1 second average delay value

$T_{\mathrm{xi}}\left(\stackrel{\&OverBar;}{t}\right)=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{T}_{\mathrm{xi}}\left(t\right)/N$

From-the light transmission delay value Tyi of main website (t), the average delay value in 1 second

$T_{\mathrm{yi}}\left(\stackrel{\&OverBar;}{t}\right)=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{T}_{\mathrm{yi}}\left(t\right)/N$

1 second send to the nominal time interval code stream standard average of slave station by main website

Wherein, N determining apart from length by optical communication transmission network MS master-slave station.

T _Xi(t) definition is that the 1PPS of main website rising edge of a pulse is that the regeneration UTC1PPS rising edge of a pulse that starting point arrives slave station is the time interval difference between the point, and it is the end-to-end propagation delay time value at MS master-slave two ends.At C _MarkT in cycle _Xi(t) only occur once

Cycle is judgement T _Xi(t)〉T _Yi(t) or T _Xi(t)＜T _Yi(t) dimension one coordinate.C _MarkCycle namely

The time interval then the corresponding bit frequency of leading be starting point (can be with frame head or not be with frame head) with the 1PPS rising edge alignment of main website.Be that this leads complete " 1 " code that bit frequency is 1KHz, namely main website is toward the 1MS standard time interval code stream of downstream broadcast.T _Xi(t),

With

Only occur once in the cycle at 1ms, do not have second pulse and occur.Although this rising edge can be introduced Randomized jitter may be very large, but per second has 10-8000 time retest, obviously directly comparing precision than two station 1PPS will increase many times, thereby effectively filtering

The randomized jitter value.

Survey accurate T _Xi(t) the modulation /demodulation error all equilibrium compensation during the meaning of value can will be transmitted in SDH and other optical communication transmission network network the time is continuous continual characteristics with the characteristics that keep TID＜1ns time interval code stream.Time reference 1PPS+TOD from main website to all own synchronous slave stations transmissions, 1PPS, E1+1PPS, E1+DCLS etc. from.

Arrive slave station take master clock regeneration UTC atomic time (synchronously more high-grade after) time reference 1PPS initial point as starting point (band timestamp frame head) after through the optical communication transmission network bearer network in main website, from clock will set up from clock regeneration UTC atomic time time reference point 1PPS _FromThe initial point place demodulates this point.

t ₂=1PPS _FromInitial point+T _Xi(t) be t ₂-t ₁=T _Xi(t)

Loopback is measured C value: C=T _Xi(t)+T _Yi(t)

In main website,, send by regeneration UTC atomic time time reference 1PPS initial point from main website

This value of cycle is not integer, and it is irrealizable relying on synchronization frequency division, and adopts the DDS technology to realize, but the clutter interference of introducing then is to introduce error TID level to increase phenomenon.And adopt The time interval code stream of frequency, the two-way comparison of carrying out of the slave station that goes directly.

Regeneration UTC atomic time split-second precision Frequency Synchronization net is exactly the technology of graduation transmission and purification temporal frequency precision.Utilize high accuracy Frequency Synchronization technology with differed from 200,000,000 years one second the atomic clock oscillator be better than 1X10 ^-15The graduate level Four Synchronization Network node that is formed by HTF-BITS equipment that is delivered to of stability:

Caesium≤± 5X10 ^-14/ day, rubidium≤± 5X10 ^-14/ day, X ₀₁≤ ± 1X10 ^-13/ day, X _O2≤ ± 5X10 ^-13/ day, X _O3≤ ± 1X10 ^-12/ day.

Because the particularity of this physical quantity of time, it must be continuously continual, if produced phase jumping in the transmittance process, the frequency kick, in the TID of actual measurement (time interval deviation), just have kick to occur, serious just might now lose second or the jump second generation.And the time step is an event that can't reverse recovery.Obviously the transmission, the particularly rule of the transmission in fiber medium of super high precision time reference must be perfectly clear.If the super high precision time reference of main website is damaged the minimum slave station that is delivered to, this is only the essence of time transmission.

The Frequency Synchronization that the present invention adopts with the frequency of main website and the frequency relative bias of slave station≤± 5X10- ¹⁴/ day.Relative phase deviation PD≤± 2ns/ days≤± 5ns/ days≤± 20ns/ days, wherein, the MS master-slave frequency and phase discrimination zero passage detection Phase Lock Technique of 8KHz.Be successfully completed slave station and (be generally X from clock ₀) " flex point " follow the tracks of master lock due to master clock (caesium clock for example, rubidium clock) " zero point ", here " flex point " and " zero point " are specific terms of zero passage detection Phase-Locked Synchronous technology, tell that on the one hand we are that the steady track that slave station enters the desirable second-order loop of loose coupling is compared ± MX10 with master clock after the stage zero point from " flex point " of station clock ^-N/ day, change point, that is to say, the control word of controlling clock when us carve at a time into ± when (1 ~ 2) bit changes, the fundamental frequency accuracy is positive and negative two the corresponding points that swing from the clock highest stabilizing, because it is the same that the mirror image of pendulum swings zero crossing, Here it is eliminates the Optimal Control technology of drifting about, on the other hand, be exactly " flex point " of its synchronously more high-grade master clock " zero point " " zero point " of main website clock, flex point be zero point corresponding, also change with the difference of place node location in Synchronization Network.That is to say, all be relative with flex point " zero point " of various grades, and the flex point of caesium clock is the regeneration UTC atomic time temporal frequency " zero point " behind it and national time service center " zero point " synchronizing comparison.The rest may be inferred, forms the node of level Four split-second precision Frequency Synchronization net.

The 8000PPS-1000PPS-100PPS-10PPS-1PPS series that is formed as benchmark by (take the UTC1PPS initial point) of main website clock generating

The synchronization of time intenals code stream is realized two-way transmission transmission and reception in optical fiber, and realizes two-way comparison, synchronous technology.Principle and the part technology of the two-way temporal frequency comparison of Time Tech TWSTFT satellite were transmitted for the optical fiber communication transmission system time of carrying out, received.Design that a kind of special optic fibre optical communication time interval code stream based on FPGA transmits and receiving chip (＜1ns).

The key element of precise synchronization:

(1) because Frequency Synchronization does not have too much requirement to time delay, so finishing of high-precision Frequency Synchronization is controlled at 5X10 with the first three items error of formula in 1. ^-14/ day be PD＜± 1ns/ days in.

(2) thus the low phase noise platform of HTF-BITS equipment has guaranteed what in a short time (10-10000 second) can realize from station clock

Duplicate measurements will be measured precision and be improved Doubly, N is the number of times of duplicate measurements in 1 second; τ is the time (unit second) of observation test, according to the clock of different stage, can be 10-10000 second or longer, can select according to specific requirement, makes

(shake of 3-5us) filtering, this just make three key index FD of the UTC atomic time temporal frequency benchmark of slave station clock regeneration＜=± 5X10 ^-14/ day, PD＜=± 2ns, TID＜=± 1ns.

Have certain length of delay from main website clockwork elapsed time benchmark output unit to the optical transmission device interface, also there is a very little length of delay in the light E/O optical fiber of making a start.The E/O of main website interface is the transmission delay value of optical fiber to slave station E/O interface, this value generally equal people of engineering opening starting stage for compensating to Txi (t)=Tyi (t).The optical fiber communications receiving equipment outputs to temporal frequency equipment input port and also has certain length of delay.

The propagation delay time asymmetry change of optical fiber is main.Also proof in the practice, the propagation delay time of optical fiber is with external environment and the reason such as aging thereof, long-term temporal evolution, rather than a definite value.A passive type compensation carrying out asymmetric difference when only relying on engineering opening is far from being enough.Therefore the Changing Pattern of measuring adopts the compensation of front end fiber optic network automatic equalization.

Advantage:

(1) balanced asymmetric difference makes T _Xi(t)=T _Yi(t), △ T _Xiyi(t) ≈ 0.

(2) reduce simultaneously or increase the one direction drift value of introducing owing to reasons such as temperature, remain the nominal (C of A → B or B → A _Mark) time delay value remains unchanged for a long period of time.Guarantee the identical of bidirectional service data link channel, and the constant intelligent locking of long term maintenance steady state value.

(3) change T _Xi(t) value namely changes the slope of MS master-slave coordinate and is split into scope such as Fig. 1 a, Fig. 1 b Interior back and forth variation.For accurately determining

Put and find accurately

The mirror image symmetric points are significant.

(4) from A → B → C → ... → N step by step equalizing fiber compensation guarantees 2000Km(or 1000Km) direct route of distance, i.e. transmission line time delay value between two big cities

△ T _Xiyi(t)≤± 1ns or (± 5ns) technically, be of great immediate significance economically.Also can 1000Km, direct route between two big cities, final slave station (slave station that cesium-beam atomic clock or rubidium atomic clock form) comes isostatic compensation.Front end optical-fiber time-delay automatic equalization phase-locking compensation and rear end electricity mouth, based on the time-delay network that FPGA forms, the electricity mouthful time interval delay equalization phase-locking compensation of composition.The balanced phase-locking compensation of electricity mouthful is deadline Frequency Synchronization between the HTF-BITS of primary HTF-BITS in the MS master-slave station and slave station, finishes without interior and carry out two-way time interval bit stream data link list, does not change T _Xi(t) ≠ T _Yi(t) out and out situation, the i.e. in esse actual state T of transmission line between the MS master-slave station _Xi(t) ≠ T _Yi(t) asymmetrical state still exists.Bidirectional service data code stream passage is still asymmetric, finishes and only have on the two-way time interval bit stream data comparison passage

Work as T _Xi(t)＞T _Yi(t) time,

Work as T _Xi(t)＜T _Yi(t) time

Utilize in a word the mirror image symmetry principle in the FPGA design, to utilize 8000PPS-1000PPS-100PPS, main website is synchronized with 125us cycle of 1PPS ~ 10ms cycle criterion time interval is delivered to the realization of slave station, and the realization of two frequency and phase discrimination zero passage detection of front, will

The randomized jitter noise filtering.With △ T _Xiyi(t) precisely measure, realize the synchronous Jing Du＜=1ns of MS master-slave relative time.

The time delay value T of optical fiber _Xi(t), T _YiAccurately measuring (t) also has other measures (instrumentation) to accurately measure out in engineering construction.Returned by electric choma again and measure the C value, its error be the optical terminus machine equipment electricity mouthful at two ends time delay value (although this value is very little, by light-electricity, electrical-optical conversion generation.C=T _Xi(t)+T _Xi(t)+T _{Equipment sends}(t)+T _{Equipment receives}(t)

Wherein, T _{Equipment sends}(t), T _{Equipment receives}(t) general value should be very little, and asymmetric difference is less, may be slightly variant for the equipment of different manufacturers, should say employing

Calculate the propagation delay time with the correction-compensation terminal equipment, in the super high precision time synchronized or in the superhigh precision time synchronized, give correction-compensation, make T _{Equipment sends}(t)=T _{Equipment receives}(t) also be easy to realize.Thereby when engineering opening, precisely measure optical fiber T _Xi(t), T _Yi(t), make the asymmetric Cha Zhi＜=1ns of propagation delay time at MS master-slave two ends neither difficult matter, this method also can be pressed the three-dimensional coordinate algorithm at the MS master-slave two ends, make the 1PPS initial point of main website and slave station, and relative time interval Wu is Cha＜=1ns.

The super high precision time interval deviation of long-term Wei Chi＜=1ns is set up Synchronization Network networking principle and the method for reliable and stable level Four temporal frequency benchmark.

Embodiment 1:

Experiment lab simulation 50km optical transport network, frequency and phase discrimination zero passage remote control " loose coupling " the frequency of phase locking simultaneous techniques 10mhz low phase noise output system platform of resurveying, asymmetric difference, the balanced phase-locking compensation of three-dimensional time coordinate remote measuring and controlling loose coupling, experimental result: Frequency Synchronization: ± 5x10 ^-14/ day, time synchronized:＜± 20ns/ days.

The cesium-beam atomic clock of (private network that comprises configuration caesium atom) of three caesium atoms at the national communication network center in the underground optical communication transmission system and drug in some provinces and national time service center (Shaanxi Observatory) and take the time service center as main website.Set up China's key Synchronization Network in the super high precision temporal frequency whole nation, finish the high-quality atomic clock and (be better than 1x10 ^-15/ day) synchronous with principal and subordinate's temporal frequency, the super high precision of technical grade cesium-beam atomic clock.As shown in Figure 2, main website: Shaanxi Observatory, time service central laboratory of country embeds the asymmetric poor unit that claims of the balanced phase-locking compensation propagation delay time of reception three-dimensional time coordinate remote measuring and controlling " loose coupling " that has two-way timing code flow data link to send output unit and also embedded by the outer slave station cesium-beam atomic clock of 1000km, and returns main website and realize that two-way timing code fluxion is accordingly to the unit.

The precision of temporal frequency is better than 1x10 ^-15~ 1x10 ^-16Level (or higher) that is to say that main website clock (Shaanxi time) is higher than 2 to 3 orders of magnitude of technical grade caesium clock at least.

The T of main website _Xi(t)+T _Yi(t)=C _i(t) or slave station T _Xi(t)+T _Yi(t)=C _i(t)

Select C _Mark＞C _i(t) value, the 1000km optical fiber one way propagation delay time of 1550.12 wavelength is about 4897619.5ns, namely about 4.897ms.Be C _i(t)＜and 10ms, so C _Mark=10ms; C _Mark-C _i(t)=20.4761us.

T from the main website to the slave station _Xi(t) and slave station to the T of main website _Yi(t) value, the instantaneous value that objectively is any moment all is definitely unequal.That is, the asymmetric difference of propagation delay time is absolute being.

Two passages

Equate it is relative, temporary transient, want to make

The changing value that must regularly measure it carries out phase-locked isostatic compensation and proofreaies and correct.

Set up following three-dimensional time coordinate:

(finished Frequency Synchronization ± 5x10 for sending to the clock of slave station with a starting point by the introduction of front from 1pps master's initial point time reference point of main website ^-14/ day more than), with from this low noise of the low phase noise output system of station clock (＜1ns) regular two-way comparison realizes relative remote measuring and controlling " loose coupling " Phase-Locked Synchronous from the three-dimensional time coordinate that main website sends take me as main high-speed and high-efficiency.Set up the relative time precision to be better than ± basis of the slave station time base station of 2ns is precisely to measure With

Mean value or root mean square and balanced phase-locking compensation correction, set up the 1pps of slave station from the relative time deviation of initial point (if measurement＜1ns) then:

Here refer to the backbone node of key Synchronization Network and the relative Long-term that waves at national time service center.Certainly be better than ± prerequisite of 2ns is that the scale of measurement in the time interval is to be better than 1ns.Background phase noise and the reverse isolation degree of principal and subordinate's low phase noise system are respectively:

Phase noise (10MHZ radio frequency)

1Hz	-115dBc/Hz~-125dBc/Hz
		10Hz	-135dBc/Hz~-145dBc/Hz
100Hz	-145dBc/Hz~-155dBc/Hz
		1KHz	-155dBc/Hz~-160dBc/Hz
10KHz	Be background below the-165dBc/Hz(to make an uproar mutually-165dBc/Hz)

The reverse isolation attenuation is better than 125dB, and rubidium clock and crystal clock will relax.The purpose of setting up the low phase noise platform is to guarantee that clock (refers to that jittering noise and the shake of the time interval of time between the 10s ~ 10000s) are better than 1ns in a short time.

Embodiment 2:

Rely on level Four temporal frequency Synchronization Network to form national split-second precision Frequency Synchronization net.By national time service center with have each specialized communication industry that three cesium-beam atomic clocks (hydrogen atomic clock) form (such as China Mobile, CHINAUNICOM, national defence time service center ... .) etc. form national (0 grade of super high precision temporal frequency reference frequency≤± 5X10 ^-15/ day time≤± 1ns/ days ,≤± 5X10- ¹⁵/ 7 days time≤± 1ns/7 days ,≤± 5X10 ^-15/ the year≤± 1ns/.

1) from the superfine backbone network of automatically tracing to the source at national time service central master station-national communication center, realize that by three above direct routes frequencies realize that frequency and phase discriminations " zero passage " detect, remote control " loose coupling " is phase-locked traces to the source automatically, make frequency≤± 5X10 ^-15Regularly interior (1 day or 7 days) by the bit stream data chain comparison of the two-way time interval of direct route, is found out because of the Changing Pattern of optical transport network propagation delay time, the △ T that had both produced again in/sky _XiT _Yi(t) situation of change, slave station adopt front end optical-fiber time-delay automatic equalization correction-compensation phase-locked, make T _Xi(t)=T _Yi(t)

The frequency discrimination here refers to C _MarkThe frequency in cycle

Comparison 8000PPS-10PPPS-1PPS, to begin to the relative time interval error that makes eventually the vertical 1PPS initial point of slave station construction and main website≤± 1ns/ days (or≤± 2ns/ days).Because the variation of time does not affect the Frequency Synchronization benchmark, time delay only is that the asymmetric difference that the time delay value of the transmission channel of optical transmission communication network has occured to increase or reduce or draw changes, this can not lean on the Frequency Synchronization reference frequency to change or phase change is realized, and must keep slave station-main website between the two by optical fiber automatic equalization from the end front end

This nominal definite value realize (perhaps in the slave station rear end by the electricity mouthful, being in the bit stream data comparison of the two-way time interval of slave station, to realize after the opto-electronic conversion) all time data code stream transmission of the UTC atomic time that an important link is the slave station clock regeneration in the two-way time interval bit stream data comparison return the intention and meaning that main website carries out time check, i.e. steady track " loose coupling " Phase Lock Technique.

At national time service center and every profession and trade optical transmission communication network center, embed the two-way time interval data code stream contrast of HTF-BITS split-second precision Frequency Synchronization unit, variation after national super high precision backbone network (hundreds of kilometer ~ several thousand kilometers) distance realizes " loose coupling " frequency and phase discrimination zero passage detection, adopt two-way slave station to return main website and check that verification unit has plurality of advantages:

Relative frequency deviation and the phase deviation of the clock of the node that it is synchronous known very accurately by periodic check main website (both national time service center).

Main website can measure the relative time spacing bias between its product of each slave node 1PPS backtrack test accurately.

Whether main website can detect slave station regeneration UTC atomic time time message accurately automatically has error code to produce that jump second is lost second and bit error probability is much.

If slave station clock setting limit performance alarm will report main website from the operating state of station clock.Whether main website just can be sent the early warning indication to marginal state by the clock of synchronous slave node to each so, keeps stability, the reliability of super high precision temporal frequency Synchronization Network.Realize the low interruption rate of the whole network.Like this by national time service center be delivered to the whole nation each communication hub super high precision temporal frequency benchmark keep long-term reliable and stable work.

2) the superhigh precision Frequency Synchronization of automatically tracing to the source at national communication hub-all provinces, municipalities and autonomous regions center.

Communication center, the whole nation refers to China Mobile, China Telecom, CHINAUNICOM, national defence communication network, powerline network center .... etc., they are by jointly setting up superfine backbone network with national time service center.At national communication center (comprising alternative communication center) three atomic clocks are arranged, and the air navigation satellite system (Big Dipper, GPS etc.) of reception temporal frequency benchmark is arranged, and participation " day net " is in-flight time frequency Frequency Synchronization net.The star atomic clock detection check comparison work of single satellite, the state that can be the controlled atomic clock in the satellite in China's Beidou satellite navigation system provides regularly unsteadiness, auxiliary national time service center.。Deng, the change in long term of checking Big Dipper temporal frequency Synchronization Network and the super thresholding situation of control system.

The Main Function of each message center then be provide in the communication network zone of administering separately for them regeneration UTC atomic clock time and frequency standards (being so-called main website clock " zero point ") and national time service center compare relative frequency Zhun Que Du＜=± 5X10 ^-15/ day, relative phase Pian is Cha＜=± 1ns/ days, relative time interval Pian is Cha＜=± 1ns/ days.

As the technical indicator standard of main website " zero point ", set up the regeneration UTC atomic time temporal frequency benchmark of communication network separately, be all provinces, municipalities and autonomous regions communication network management center, temporal frequency " zero point " is provided.Some provinces and cities' center configuration of synchronizer configuration rubidium atomic clock (Rb) of (or claiming one-level node benchmark) general provinces and cities message center has cesium-beam atomic clock.Consist of the national one-level backbone communications network of every profession and trade communication network.Intown synchronizer generally remains with the purpose of the synchronous time service receiving element of GPS/ Beidou satellite navigation temporal frequency and is many one and joins synchronously just input channel by " day net " temporal frequency in the each province.Add three ground direct routes " earth mat " and with face mutually provinces, cities and autonomous regions to few two and realize that temporal frequency detects, in order to verify the long base stability of self, the method of such 1 grade of node verification is objectively judged the timing unsteadiness of all transmission lines timing labile states of the people and node, and that what is called " third party " comparison technology adopts this measure to guarantee stability and the low interruption rate of the superhigh precision temporal frequency of optical transport network.

Be as shown in Figure 3 the schematic diagram of example take Chengdu.

By above measure, HTF-BITS equipment configuration rubidium clock realize with the relative frequency Pian of main website (national communication network message center) Cha＜=± 5X10 ^-14/ day, relative phase Pian is Cha＜=± 2ns/ days relative time interval Pian is Cha＜=± 2ns/ days.

And the regeneration UTC atomic time of " zero point " temporal frequency benchmark of the key Synchronization Network of the secondary in take this technical indicator as provinces, cities and autonomous regions' scope the prefecture-level message center node time frequency reference when producing secondary regeneration UTC (comparing with the provinces, cities and autonomous regions message centers) that desynchronizes.Relative frequency Pian is Cha＜=± 1X10 ^-13/ day, relative phase Pian is Cha＜=± 5ns/ days, relative time interval Pian is Cha＜=± 5ns/ days.

The communications industry that condition is good such as China Mobile all configure rubidium clock, and the general configurable highly stable crystal clock Xo that is enhanced to: three grades of nodes should be counties and districts' message center.The level HTF-BITS of counties and districts, the reinforced Xo of a general configuration ₁Or the relative frequency Pian that its its standard of regeneration UTC atomic time temporal frequency of plain edition Xo is master clock Cha＜=± 2.3X10 ^-13/ day, relative phase Pian is Cha＜=± 10ns/ days, relative time interval Pian is Cha＜=± 10ns/ days.

The level Four node is base station and residential quarter, small towns HTF-BITS, generally with Xo ₂And Xo ₃(the cheap crystal clock of single constant temperature low phase noise is from clock.Regeneration UTC atomic time temporal frequency benchmark and main website compare relative frequency Pian Cha＜=± 5X10 ^-13/ day, relative phase Pian is Cha＜=± 20ns/ days, relative time interval Pian is Cha＜=± 20ns/ days.Suggestion about the distribution method of 1us-1.5us split-second precision reference index:

" day net " in-flight time Frequency Synchronization net, rely on the Big Dipper or GPS after receiving four satellites, to set up Three-Dimensional Solution algorithm equation, the Big Dipper/GPS receiver all can obtain with UTC Bi Dui＜=± the split-second precision benchmark of 300ns.The receiver of excellent performance, Ke Huo De＜=± the superhigh precision time reference of 50ns.Unique defective is the limited and cost of the security reliability height of comparing with earth mat.

And " earth mat " by the optical communication network that extends in all direction be the split-second precision frequency equipment of supporting body form " " proposed specifications of the frequency drift value of G811, G813 distribution 18us press in frequency synchronization section existing clear and definite suggestion in ITU to earth mat.The overwhelming majority has been left terminal and last " several kilometers " communication network clock for, and time synchronized has two reasons, and the overwhelming majority is the time server that relies on GPS to form, and is kept by " day net ", is equivalent to the accurate method of synchronization.In case GPS, namely " day net " breaks down, and keeping of time precision is very difficult, in 3G epoch and forthcoming 4G epoch, to the very high 1 ~ 1.5us of the requirement of time precision.The time drift index of this 1 ~ 1.5us refers to the air interface stomion.Wireless and wired, or the time interval deviation between wireless and the wave point, whenever all necessary≤1 ~ 1.5us.In the integrated Synchronization Network of the novel unification that level Four super high precision temporal frequency Synchronization Network forms, the time of equipment and transmission network, its accurate transmission damage was $\&le;\&PlusMinus;\sqrt{1^2+1^2+2^2+5^2+{10}^2+{20}^2+{20}^2}=\&PlusMinus;30.52\mathrm{ns}.$ That is to say that adjacent base station two adjacent provinces, cities and autonomous regions joins.Obviously the maximum of leaving the time interval deviation permission of base station air interface for is 960ns ~ 1460ns.Namely relax the time drift tolerance limit amount of last " one kilometer " network, can arrive the flexibly space of tolerance of all kinds of air interfaces to the base station, thereby guaranteed the reliability of whole temporal frequency Synchronization Network.

Claims (8)

1. claim 1 is asked for protection the method that the asymmetric difference of a kind of time delay accurately measures, and it is characterized in that:

1) set up the optical communication transmission network network in split-second precision frequency BITS equipment, lead-stand and pass through optical communication transmission network network passing time reference signal between the synchronizer, main website and slave station time synchronized adopt the two-way mode of comparing;

2) time interval deviation of the following calculated with mathematical model MS master-slave synchronizer of employing:

①

In 1. formula, Es represents principal and subordinate's relative time spacing bias;

E0 represents principal and subordinate's initial time spacing bias;

The remaining time drift error of expression principal and subordinate Frequency Synchronization after using frequency and phase discrimination zero passage detection Phase Lock Technique;

Δ T _Xy(t) represent asymmetric difference, i.e. Δ T _Xy(t)=| T _x(t)-T _y(t) |, T wherein _x(t) expression is passed through the optical communication transmission network network to the time interval value between the slave station clock synchronization device signal, T by the signal of main website clock synchronization device transmission _y(t) signal process optical communication transmission network network to the main website clock synchronization device of expression slave station clock synchronization device transmission receives the time interval value between the signal;

The randomized jitter noise that the expression optical-fiber network is introduced when the passing time benchmark;

1. first three items is finished by long-distance remote control loose coupling frequency and phase discrimination zero passage detection Phase Lock Technique in the formula, and error is controlled at ± 5X10 ^-14/ day;

3) adopt the three-dimensional time coordinate to accurately measure Δ T _Xy(t): in main website, measure loopback cycle C value, loopback cycle C value is:

C=T _Xi(t)+T _Yi(t), i represents bit quantity, chooses nominal period C according to C values different in the following table _MarkValue,

Loopback cycle C <125us <250us <1ms ... <10ms <100ms ... Nominal period C 125us 250us 1ms ... 10ms 100ms ...

Work as T _Xi(t)=T _Yi(t), △ T _XiT _Yi(t) ≈ 0

The time, realize that the propagation delay time of the two-way comparison transmission of master station and follow station and back equates;

Work as T _Xi(t)＞T _Yi(t) time,

Work as T _Xi(t)＜T _Yi(t) time,

Namely

With △ T _XiT _Yi(t) precisely measure, realize that the MS master-slave relative time is synchronous.

2. the method that accurately measures of the asymmetric difference of a kind of time delay according to claim 1, it is characterized in that: described two-way comparison mode is two-way time code stream comparison.

3. the method that accurately measures of the asymmetric difference of a kind of time delay according to claim 1 is characterized in that: the synchronous precision of described realization MS master-slave relative time for≤± 20ns.

4. the method that accurately measures of the asymmetric difference of a kind of time delay according to claim 1 is characterized in that: the synchronous precision of described realization MS master-slave relative time for≤± 10ns.

5. the method that accurately measures of the asymmetric difference of a kind of time delay according to claim 1 is characterized in that: the synchronous precision of described realization MS master-slave relative time for≤± 5ns.

6. the method that accurately measures of the asymmetric difference of a kind of time delay according to claim 1 is characterized in that: the synchronous precision of described realization MS master-slave relative time for≤± 2ns.

7. the method that accurately measures of the asymmetric difference of a kind of time delay according to claim 1 is characterized in that: the synchronous precision of described realization MS master-slave relative time for≤± 1ns.

8. the method that accurately measures of the asymmetric difference of a kind of time delay according to claim 1 is characterized in that: adopt the low phase noise platform of split-second precision frequency BITS equipment, improve so that measure precision

Doubly, wherein N represents the number of times of duplicate measurements in 1 second, the time of τ observation test.

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