CN108768506B - Multi-element multi-frequency common-view comparison time service method based on common threshold - Google Patents

Abstract

The invention discloses a multi-element multi-frequency common-view comparison time service method based on a common threshold, which adopts more than three optical routes as a plurality of time frequency transmission routes participating in the common-view comparison, adopts time interval codes of more than two frequencies to transmit time frequencies, selects an equal time delay wavelength pair of an optical fiber O wave band to obtain the time from a main station through static cross transmission as the common threshold, and realizes the time service of a slave station through the common-view comparison. The usability and the reliability of the synchronization technology realized by the phase comparison intelligent control phase locking of the honeycomb star-shaped strip multi-element multi-frequency co-vision 'common threshold' ratio are as high as more than 99.99997%.

Description

Multi-element multi-frequency common-view comparison time service method based on common threshold

Technical Field

The invention belongs to the technical field of precision measurement and precision intelligent phase-locking synchronization, relates to a time service method, and particularly relates to a multivariate multi-frequency common-view comparison time service method based on a common threshold.

Background

The continuous development of information technology, the demand for the time frequency reference accuracy has gradually increased to picosecond level, and a high-precision time service technology is urgently needed to be researched and developed, a high-precision time service network is built, a high-quality clock source in a laboratory is transmitted to a line node without damage, the high-precision time service network is served to the national civilization, and high-precision basic guarantee is provided for various industries.

From the physical characteristics of the optical fiber, the parasitic random noise of the optical fiber transmission along with temperature and the like standardizes the optical fiber length optical route, normalizes the comparison of the time interval reference signal of landing to a multi-frequency multiple common-view 'common threshold', and the actual transmission distance of the optical fiber length L (x, y, z) also changes randomly, (the point to be explained here is that the geographic position coordinates of a certain point N (x, y, z) and the optical fiber transmission optical route lengths of two certain points L (x, y, z) are two concepts which are not completely the same), so the method is a technical problem which needs to be considered in ultra-precise measurement, ultra-precise control and master-slave synchronization; but the random variation of the optical fiber time delay value of the length of N km is measured by using an extremely accurate time frequency reference (more than 1E-15), and the single fiber bidirectional performance can reach and realize that the measurement precision of the ps-level comparison measurement time interval is less than 5 ps. The physical micro-change DeltaL of the length of an optical fiber A → B which is thinner than hair and is away from N km (N is 20-200) is researched, the dimension of the physical micro-change DeltaL is DeltaL/km. ℃, and the physical micro-change DeltaL is one kind of parasitic random noise change which changes along with the transmission distance and the temperature, so the ultra-high precision time-frequency transmission needs to research the extremely slow change rule of the optical fiber transmission and can also be generally considered as the synthetic comprehensive result of time delay random noise change and aging drift. If the drift accumulated random variation noise of optical fiber transmission is not divided, stripped, compressed and filtered, the high-precision high-grade clock of the master station in the foundation time service system cannot transmit the real stability and frequency accuracy better than the time frequency reference of 1E-16/day to 1E-17/day to the slave station clock nodes in the same-grade clock mutual synchronization and master-slave synchronization beyond more than 2000km, so that the local clock cannot distinguish the high-grade ultrahigh-precision time frequency reference of the real and fake master stations, and the application of cellular star-shaped strip-shaped multi-frequency multivariate co-view 'common threshold' comparison intelligent control phase locking can be realized, and the ultrahigh-precision time frequency reference of 1E-16/day can be transmitted to the nodes beyond 2000km seamlessly, transparently, accurately, stably, safely, reliably and robustly.

The negative effects of dispersion drift accumulation (the dispersion coefficient is xps/nm.km, and the dispersion drift accumulation is xps/nm2.km) in fiber transmission are caused by random changes of the optical frequency transmitted by the fiber and the length of the fiber, which are not extremely slow changes of the master station clock source and must be divided, stripped, compressed and filtered. The system also needs compensation and control, but the special performance of optical fiber transmission has many advantages compared with wireless communication, the method and means for telemetering, remote control and intelligent control are easy to realize, the visible and visible device is simple and convenient, the detection and measurement are not directly influenced by weather, and the equipment cost is low. Therefore, the ultra-high precision time frequency reference can be transmitted by fully utilizing the fiber resources.

The method adopts the MRT main station loopback + optical fiber 'on-line monitoring' patent technology (an on-line monitoring method of optical fiber transmission time delay of an optical communication network) (patent application No. 201310384396 publication No. CN103441795A) to segment and strip various random variation noises of the optical wave optical route optical fiber time delay when the optical fiber is transmitted: the multiple random variation noises have daily fluctuation and monthly drift accumulation caused by temperature random variation, and the drift slope caused by annual drift accumulation (positive drift accumulation from severe winter to summer and negative drift accumulation from summer to severe winter) optical fiber transmission optical path dispersion drift accumulation … … and the like is equivalent to 1E-13/day to 1E-16/day or even higher slow drift variation.

Disclosure of Invention

The present invention is directed to overcome the above disadvantages of the prior art, and provides a multi-component multi-frequency co-view comparison timing method based on a common threshold.

The purpose of the invention is realized by the following technical scheme:

the multi-element multi-frequency common-view comparison time service method based on the common threshold adopts more than three optical routes as a plurality of time frequency transmission routes participating in the common-view comparison, adopts time interval codes of more than two frequencies to transmit time frequencies, selects the time from a master station obtained by static cross transmission of an equal delay wavelength pair of an optical fiber O wave band as the common threshold, and realizes the time service to a slave station through the common-view comparison.

Further, the above specific scheme that three optical routes are used as the multiple time-frequency transmission routes for the co-view comparison is as follows: one optical route conveys 1PPS + TOD, and the other two optical routes are used for conveying frequency signals with the same frequency.

The frequency range of the frequency signals transmitted by the other two optical routes is 100Hz to 10 kHz.

Further, the static cross-propagation is to use a static wavelength cross-dispersion compensation method to propagate the time.

Furthermore, when the time frequency is transmitted, the intelligent control phase locking technology is used for dividing, stripping, compressing and filtering a plurality of kinds of randomly changed parasitic noise transmitted by the optical fiber, so that the time delay value of the optical fiber is constantly controlled within an allowed tolerance range.

Further, the static cross-forwarding is: by utilizing the inherent characteristic of optical wave transmission during optical fiber transmission, when the equal time delay wavelengths on two sides of the zero dispersion center 1310nm of the O wave band in the G.652 optical cable are subjected to single-fiber bidirectional transmission or simultaneous static cross transmission in the same optical fiber, the dispersion coefficient slopes of two optical waves slowly change along with the temperature and are the inherent regularity of mutual positive and negative differential change all the time, and the optical fiber dispersion accumulation adaptive compensation is realized by utilizing an intelligent control phase locking technology and a static cross transmission method.

Further, the time delay asymmetry difference of the optical route is controlled within the range of 20ps to 5 ps.

Further, more than three optical routes are transmitted simultaneously and compared, and local adjacent clocks or clock groups at the same level also need to have three optical routes to be transmitted back to the master station, compared with each other, and most of the decisions are made.

The invention has the following beneficial effects:

(1) the tiny deviation in the transmission process of one route (or two routes) is not easy to find, and particularly, the judgment of who is correct and who is bad is very difficult for the time frequency reference information transmitted by wireless communication. The ' common threshold ' judged by the ' common threshold ' of the multi-element multi-frequency common vision ' of the optical fiber honeycomb star-shaped strip transmission is an assembly (or unit plug-in card) formed by a ' chip ' (or FPGA) special for electrical port hardware and the like, and the multi-element multi-frequency input interface has at least 16 paths of comparison of the ' common threshold ' of the common vision, so the usability and the reliability of the synchronization technology realized by the comparison of the ' common threshold ' of the multi-element multi-frequency common vision of the honeycomb star-shaped strip and the phase-locked intelligent control are higher than 99.99997 percent.

(2) Slow drift in the transfer process of one route (or two routes) is difficult to split and strip, and in master-slave synchronization: the optical fiber length in the optical fiber transmission is two-dimensional second-order random variation along with extremely slow daily fluctuation, month drift accumulation, accumulated year drift accumulation and dispersion drift accumulation of temperature, the level of a clock source at a slave station is generally lower by one level than that of a master station, the aging rate of the time base is high, extremely slow random variation noise cannot be segmented and stripped, the cellular star-shaped strip transmission and the multi-element multi-frequency co-view comparison are carried out, and the beneficial technical effects brought by the MRT loopback detection of the master station are as follows:

the master station is eHPRTC noise which can be divided and stripped randomly and has a frequency of more than 8.64 ps/day;

the master station is HPRTC noise with random variation capable of being split and stripped for more than 86.4 ps/day;

therefore, the network platform of the four-stage master-slave synchronous optical fiber transmission uniform time frequency reference support network of eHPRTC → HPRTC → ePLRTC → PRTC → LPRC → DCXO can avoid the transmission damage caused by the inherent random variation noise of the error tracking optical fiber, and the best synchronous effect can be obtained

(3) The uncertainty of the transmission route in the transmission process of one route (or two routes) can not be distinguished:

the optical cable with more than 3000 kilometers is built in China, the current G.652 optical cable with the type of G.652G.655 … … and the like has more stable performance and better consistent performance accounting for 95 percent, and the distances of all the relay sections cannot be completely the same, so that accidents in the transmission process are uncertain and possibly occur at any time, and the comparison of cellular star-shaped strip-shaped multi-element multi-frequency co-view 'common threshold' is a key means for strongly judging the uncertainty;

(4) after the optical fiber system is switched in the transmission process of one route (or two routes), the time delay jump, the stability of the switched optical fiber route, and the like can not be judged. The cellular star-shaped strip-shaped multi-element multi-frequency co-view 'common threshold' comparison does not need to worry about the problem.

(5) One route (or both routes) delivery is unexpectedly interrupted, "on the fly" is a big problem. And the cellular star-shaped strip-shaped multi-element multi-frequency co-view 'common threshold' comparison shows that except for irresistible natural disasters (such as major earthquakes), the probability of occurrence in time is almost nonexistent.

(6) The cellular star-shaped strip-shaped multi-element multi-frequency common-view 'common-threshold' time service method is a good method for constructing a seamless, transparent, stable, precise, safe, reliable and robust optical fiber support network platform with national uniform time frequency reference.

Drawings

FIG. 1 is a schematic diagram illustrating changes in transmission delay values of static cross optical routes of 2 × 50km 1270nm and 1350nm in an O waveband of one optical fiber of a G.652 optical cable;

FIG. 2 is a diagram of a regular hexagonal star topology unit structure transfer optical network;

FIG. 3 is a schematic diagram of a G652Nx2x50km honeycomb star-shaped strip-shaped multi-view "caged-trap" transfer network;

fig. 4 is a schematic diagram of differential burst delay wavelength versus + static cross long-distance optical transmission information;

FIG. 5 is a block diagram of the comparison and matching transmission of the G.652 optical cable, optical fiber, single fiber, bi-directional 1270nm and 1350nm 2 × 50km + static cross multi-frequency multi-component common view 'common threshold';

FIG. 6 is a diagram of a square cabinet comparing five-point normalization differential common-gate threshold comparison with intelligent control phase locking for multi-frequency multi-element bidirectional matching transmission of honeycomb star-shaped ribbon single-fiber less than 5ps to 10 ps.

Detailed Description

The invention relates to a multi-element multi-frequency common-view comparison time service method based on a common threshold, which adopts more than three optical routes as a plurality of time frequency transmission routes participating in the common-view comparison, adopts time interval codes of more than two frequencies to transmit time frequencies, selects an equal delay wavelength pair of an optical fiber O wave band to obtain the time from a main station through static cross transmission as the common threshold, and realizes the time service of a slave station through the common-view comparison.

The specific scheme of using three optical routes as a plurality of time frequency transmission routes for reference and common view comparison is as follows: one optical route conveys 1PPS + TOD, and the other two optical routes are used for conveying frequency signals with the same frequency. The frequency range of the frequency signals transferred by the other two optical routes is 100Hz to 10 kHz. The three optical routes are transmitted and compared at the same time, and local adjacent clocks or clock groups at the same level also need to have the three optical routes to be transmitted back to the master station, compared with each other and mostly judged.

When the time frequency is transmitted, the intelligent control phase-locking technology is used for dividing, stripping, compressing and filtering a plurality of kinds of randomly-changed parasitic noise transmitted by the optical fiber, so that the time delay value of the optical fiber is constantly controlled within an allowed tolerance range.

Static cross-propagation is to use static wavelength cross-dispersion compensation method to propagate the time of day. The static cross-propagation is: by utilizing the inherent characteristic of optical wave transmission during optical fiber transmission, when the equal-time-delay wavelength pairs on two sides of a zero-dispersion center 1310nm in a G.652 optical cable are subjected to single-fiber bidirectional transmission or simultaneous static cross transmission in the same optical fiber, the dispersion coefficient slopes of two optical waves slowly change along with the temperature and are the inherent regularity that the dispersion coefficient slopes change in a positive-negative difference mode from beginning to end, and the optical fiber dispersion accumulation adaptive compensation is realized by utilizing an intelligent phase-locking technology and a static cross transmission method.

And controlling the time delay asymmetry difference of the optical route within the range of 20 ps-5 ps.

The invention is described in further detail below with reference to the accompanying drawings:

fig. 1 is a schematic diagram of the comparison transmission technique of the equal delay wavelength pair + static cross multi-frequency multi-element differential common view "common threshold" as follows:

1350nm (50km) +1270nm (50km) for one set (2X 50km) +1270nm (50km) +1350nm (50km) for a second set (2+50km) of ten … …

Description of the drawings: the Group Delay-Wavelength optical fiber optical wave transmission Delay-optical wave lambda i characteristic curve of the G.652 optical cable exists in the optical Wavelength of a 1310nm zero dispersion center:

the delay values in the 2X50km range, for example 1270nm and 1350nm, are substantially the same but with little dispersion drift and a dispersion slope variation law: one is that

The other is

The dispersion coefficient is measured as Δ Dd/nm.km (only the 1260nm to 1360nm O band centered around 1310 nm). Therefore, a transmission time signal which is a differential change rule is maintained from beginning to end along with temperature change in the simultaneous in-phase transmission of one single fiber; if 2x50km of "50 km" is servo-locked and accurately controlled within a certain allowed range from the master Tx → slave Rx optical routing total delay value MRT loopback measurement "on-line monitoring" fiber delay value, as reflected in L (x, y, z) ═ Tao when two "50 km" length error values are ≦ ± 1mm (< 5ps) after being measured by "5 ps" time interval resolution (resolution), when the fiber delay servo-locking and fine control technique splits, strips, compresses, filters to < 5ps the six types of randomly varying noise that change very slowly, i.e., β λ 1270nm × 0L1+ β λ 1350nm × 1L 2+ 36ps + (-36 ps) adaptively compensates to +5ps (or-5 ps) while the optical routing of the other fiber is: β λ 1270.00nm × 2L2+ β λ 1350.00nm × 4L1 (-36 ps) + (+36ps) is adaptively compensated to-5 ps (or +5ps), so that two optical fibers are used and the equal time delay optical wave λ is transformed, one set is statically cross-compensated from O → F → a for 2 × 550km at 1270nm and 1350nm, the other set is statically cross-compensated from O → B → a for 2 × 650km at 1350nm and 1270nm, and thus two different sets of statically cross-optical routes from O → F → a and O → B → a to point a also follow the law of differential transmission. The two groups of Txk code pairs after being segmented, stripped, compressed and filtered to remove various random variation noises are transmitted to 2 × 50km, which is formed by the inherent characteristics of optical fiber transmission, and the smaller difference variation with Eo (t) as the center of a zero point crosses the zero-crossing variation from beginning to end, in other words, Eo (t) common threshold is controlled in the difference variation, and Eo (t) cascade banded transmission is maintained in the range of +/-3 xps from the center of the common threshold by multi-frequency multi-element difference common vision common threshold comparison, and is transmitted to the outside of 2000 by N × 2 × 50 km. Without the 2x Nkm static cross-transfer patented technique, the extremely slow and small drift (mainly dispersion accumulated drift) is a diverging drift accumulated error.

As shown in the transfer in the cellular star-band topology of fig. 2: the diagram is a regular hexagon star topology unit structure transmission optical network diagram, and illustrates that:

the eHPRTC '0-level clock group' -is called as an eHPRTC standard time frequency reference node by assuming that the eHPRTC '0-level clock group' is composed of two 'optical clocks' + at least more than three fountain cesium atomic clock architectures, wherein the time frequency stability and accuracy of the '0-level clock group' are better than 1E-16/day; is the Master of the national 'level 0' synchronization. The realization of mutual synchronous comparison of national '0-level' Master > 2000km optical fiber transmission firstly solves the technical problem that the ultra-high precision time frequency reference of more than two '0-level' masters is accurately, surely, transparently, stably and robustly transmitted to the opposite end. The invention adopts honeycomb star-shaped strip-shaped transmission multi-element (multi-optical route) equal time delay optical wave pair differential static crossing 2x Nkm three time sequence transmission 'five points are unified' multi-frequency multi-element common vision 'common threshold' comparison intelligent control phase locking + smooth equalization fine adjustment time delay compensation to compress the original reference 'threshold' at the time moment to '0' point 'zero crossing' swing, 'the threshold' is set to four grades of +/-40 ps, +/-20 ps, +/-10 ps, +/-5 ps, and the time interval measurement resolution thereof is divided into: 8ps, 4ps, 2ps, 1 ps.

The design scheme of comparing the differential common-view 'common-threshold' of multiple equal-delay optical waves of G.652 optical cables with 2x50km cellular star-shaped band transmission less than or equal to 2000km is shown in a general block diagram in figure 3:

(1) the "01" node is "ehhprtc node of level 0" ehhprtc node → 4 × 2 × 50km ← PRTC node → 8 × 2 × 50km ← "level 0" ehhprtc;

(2) setting that the node 01 and the node 02 are both configured with a clock group atomic clock device of a level 0 clock group, namely eHPRTC (eHPRTC time frequency stability and accuracy are 1E-16/day), and configuring a3 and an Ani at a distance of 2000km with a PRTC node composed of two cesium atomic clocks and two rubidium atomic clocks of a PRTC time reference node device;

(3) the optical fibers can be respectively used for bidirectional transmission to opposite ends, two pairs of equal time-delay light waves of 1270nm and 1350nm or 1290nm and 1330nm are selected for transmitting 1600 km-2000 km according to the star-shaped ribbon shown in figure 2;

(4) according to the optical fiber D-W curve of the G.652 optical cable and the current optical module production process CWDM:

1290nm1330nm and 1270nm1350nm have + -3 nm variations, and we use the method of appropriate matching pairs to improve the matching pair consistency to the accuracy of + -1 nm, respectively, for example:

matching and matching 1270nm +/-0.5 nm with 1350 nm- (+/-) 0.5 nm;

matching and matching 1271nm +/-0.5 nm with 1349 nm- (+/-) 0.5 nm;

1269nm +/-0.5 nm is matched and matched with 1351 nm- (+/-) 0.5 nm;

……

1264nm +/-0.5 nm is matched and matched with 1356 nm- (+/-) 0.5 nm;

matching and matching 1263nm +/-0.5 nm with 1357 nm- (+/-) 0.5 nm;

……

if the above requirement is satisfied, the theoretical estimate of the initial fixed relative deviation of the time delay by the time delay light wave is:

the Δ Dmax at 1270nm and 1350nm 50km (at 25 ℃) is:

0.072ps/nm2.km×1nm×50km＝3.6ps/nm

1290nm and 1330nm 50km (at 25 ℃) Δ Dmax is:

0.030ps/nm2.km×1nm×50km＝1.5ps/nm

the optical wave Δ Dmax introduced by the laser transmission may be increased by 3 times if matching pairing selection is not performed, i.e., the transmission noise is deteriorated by 3 times.

(5) The technology for reducing transmission damage by using equal time delay optical wave pair and static cross secondary compression comprises the following steps:

three time sequence step test:

the first step is as follows: the loop-back + on-line monitoring optical fiber time delay servo locking and accurate control of the MRT master station are realized by taking the ultra-high precision time frequency reference of '0 level of a clock group' 1E-16/day as a monitoring comparison reference signal, and when the ultra-high precision time frequency reference is used as a monitoring comparison reference signal, the negative influence introduced by the optical fiber transmission of an optical cable is divided, the temperature … … and other random variation noises during the optical fiber transmission are peeled off, the effective compression and filtering effects of the random variation noises which can reach +/-100 ps to +/-1 ps, particularly the aging drift accumulation is more than or equal to 8.64 ps/day are good or bad, and the transmission effect of the time frequency reference. Therefore, the capability of filtering various random noise strengths depends on the time interval resolution measurement scale, the level of a 'clock group' and the accurate strength of segmentation, stripping, compression and filtering.

Second step (sequence): the technical difficulty focus of the mutually synchronous multi-frequency multivariate difference common view "common threshold" comparison intelligent control phase locking transmitted from "01" to "02" or from "02" to "01" is the compensation of the time delay asymmetry of the optical wave optical route introduced by the dispersion drift of the optical wave optical route, and the like, while the time delay optical wave has slight accumulated damage of the transmission dispersion drift to the transmission delay, but after the self-adaptive intelligent control compensation is realized through the accumulated of the OEO static cross transmission five-point common view dispersion comparison of 2 × 25km, 2 × 50km or 2 × 100km, 1270nm and 1350nm or 1290nm and 1330nm which are greater than 2000km, the intelligent control phase locking can be firmly controlled within the technical index range designed by us, for example: the 50km optical fiber single-fiber bidirectional transmission adopts 1270nm and 1350nm equal-time-delay optical wave pair transmission and 2 multiplied by 50 multiplied by 20 is 2000km after static cross compression filtering, and as long as Eo (t) transmission damage achieves "ps level", other terms are easy to control. If the static cross-over effect of the 2X 100km optical route is 1 (e.g.. ltoreq.40 ps), then the static cross-over effect compression of 2X50km for 0.5 (< 20ps) for 2X 25km is 4 times (< 10 ps).

Second step (sequence): the ultra-high precision phase frequency discrimination and phase discrimination zero-crossing detects master-slave synchronous regeneration ultra-high precision UTC atomic time frequency base reference signals.

The invention of the intelligent control phase locking technology and other invention patents are jointly integrated and applied to obtain the comprehensive technical effect by comparing the cellular star-shaped strip-shaped multi-frequency multi-element differential common-view 'common threshold' ratio:

dispersion drift accumulation ≈ 0

Initial time transfer error is approximately equal to 0

Cascaded transmission error drift accumulation of optical routing is approximately equal to 0

The noise transfer accumulation is approximately equal to 0 and only depends on the inherent random noise of the slave station local clock transmitted by the optical fiber, if the DCXO double-constant-temperature high-stability SC is cut and the ultralow phase noise output is realized, the short-term second-level stability can reach 1E-13/second order, the reverse attenuation is more than 125dB, the background phase noise is less than or equal to-163 dB, and the long-term permanent operation cannot be deteriorated.

The cellular star-shaped ribbon multi-frequency multi-element differential common-view 'common threshold' comparison intelligent control phase-locked transmission technology is irrelevant to the optical fiber transmission light wave spectrum;

independent of fiber transmission distance and cascade;

the time t is irrelevant and does not change along with the change of time;

(6) optical routing light wave asymmetric difference drift accumulation of 2000km of G.652 optical cable fibers:

DWDM：

and (3) O wave band: 1260 nm-1360 nm;

and (3) S wave band: 1450nm to 1530 nm;

c wave band: 1530nm to 1560 nm;

l wave band: 1565nm to 1625 nm;

wherein 0 wave band, only a few CWDM lightwaves have been developed at present, it is very low to show the resource utilization ratio of this lightwave band, if develop and develop new "DWDM" too, can enlarge the resource utilization ratio, "ps level" only adopts 1-2 optic fibre, a G.652 optical cable also has a plurality of optic fibre to apply CWDM to the optical route of O wave band lightwave only 3 pairs, it is not high to show the utilization ratio of the optic fibre resource, and develop "DWDM" dense wavelength division multiplexing of O wave band, it is slightly different from DWDM that original C wave band has already been developed to certainly should develop and develop novel DWDM according to the inherent particularity of O wave band lightwave.

The backbone transmission network of the unified time frequency reference optical fiber support network platform adopts a cellular star-shaped ribbon transmission architecture, each optical cable of three optical cables only uses two optical fibers to form a six-in six-out multi-element transmission system, so that the safety and reliability of the unified time frequency reference optical fiber support network platform are greatly improved, the availability and the credibility are as high as 99.999996%, which is the optical fiber resource occupied by the foundation precision time service, however, the 0 wave band 1260 nm-1360 nm light wave of the G.652 optical cable not only supports two optical fibers occupied by the network platform, but also develops and develops other optical fibers into a novel dense wavelength division multiplexing DWDMo (called DWDMo is distinguished from DWDM of other wave bands) by utilizing high-precision time frequency reference, if 1nm optical route interval is selected, 100 optical routes or 50 equal delay optical wave pair static cross special performance optical route transmission systems can be added to make the future optical transmission network more and more profitable.

The G.652 optical cable occupies 95% in the construction of the optical fiber transmission network, fully utilizes the existing optical fiber resources, and successfully develops a novel dense wavelength division DWDMo with an O wave band of 1260 nm-1360 nm to transmit high-speed data communication service through independent innovation. Several wavelength division transmission channels can be added.

If dense wavelength division light wave spectrum intervals with 1nm intervals are selected to be larger than 160GHz, if equal-time-delay light wave pairs and 2x Nkm static cross transmission are adopted to automatically and adaptively compensate, equalize, disperse, accumulate and drift time pilots with the distance of 2000km or less and the distance of 5ps + lambda toi (1310nm) to control the daily fluctuation, the month drift and the year drift random change noise of each optical fiber route for transmitting communication service information to be less than or equal to 5ps, and if 2x Nkm is 2000km to transmit 100 Gbit/s-160 Gbit/s, the method can completely realize that the communication service information is transmitted at the speed of 100 Gbit/s-160 Gbit G

(7) Purifying and tracing:

the cesium atom clock tracing traces a1 level clock group of 1E-15/day, and can synchronously trace, compress and filter the aging drift 1/2D t2 of the cesium atom clock from 8.64 ns/day to 86.4 ps/day.

The cesium atom clock tracking is traced to a 0-level clock group of 1E-16/day, the self-aging drift component 1/2Dt2 aging drift can be 8.64 ns/day, and synchronous tracking compression is filtered to be within the range of 8.64 ps/day.

However, the precondition of tracing is as follows: the ultra-high precision time frequency reference of '0-level clock group' 1E-16/day can be accurately transmitted to the position beyond 2000km without errors, and the '1-level clock group' realizes master-slave synchronization. Zero-distance 'loose coupling' ultra-low phase noise purification and compression devices must be additionally arranged, so that inherent phase noise and short-term stability of atomic time frequency references of all levels can reach 'ps level'. The time frequency reference nodes of various grades must meet the requirement of ultra-low phase noise output which is suitable for the grade of the time frequency reference nodes.

In addition, the '0-level clock group' also has drift (about 3 ns/year) which needs to be traced to a reference with higher precision level, so that the extremely slow change drift can be eliminated, or the multi-frequency multi-element cooperative differential common view 'common threshold' between the '0-level clock groups' in a region can transfer the mutual synchronization ratio to enable or disable the '0-level clock group' to keep relative consistency of ultra-high precision. The '0-level clock group' also needs to find the ultra-accurate time frequency reference comparison of 1E-17/day to 1E-18/day for tracing.

(8) Unified time frequency reference "cloud" support network platform:

the method takes a network platform of a national time service center and Beijing, which adopts a honeycomb star-shaped ribbon fiber-optic supporting network, as a highest-level clock group (abbreviated as ' 0-level clock group ' eHPRTC node), realizes mutual synchronization multi-frequency multi-element collaborative difference common view ' common threshold ' comparison intelligent control phase locking, can adopt the transmission of the mutual synchronization intelligent control phase locking by ' common threshold ' comparison of honeycomb star-shaped ribbon multi-element collaborative difference common view ' common threshold ' in the whole course of Beijing → ← stone house → ← Taiyuan → ← xi ' Ann about 1600km, and firstly realizes ' ps-level ' mutual synchronization. The construction of the backup unified temporal frequency reference optical fiber network nodes for the primary and backup is the infrastructure which is firstly constructed by constructing the 1E-16/day cellular star-shaped strip transmission multi-frequency multi-component collaborative difference co-view common threshold of the ' 0-level clock group ' of the ' one-level national backbone transmission network by taking the five regional centers (+ five strategic standby nodes) as the ' 1-level clock group ' HPRTC nodes.

The availability of one optical transport route is 85%, the probability of unavailability is 15%, if two optical transport routes (primary + backup) are used, the availability is 97.75%, and the availability of three optical transport routes is: 99.6625 percent. The availability of the sixth-order is 99.999996%, and in the 'ps-level' transmission, if the master station (the time frequency reference of the '0-level clock group') adopts the mutually-synchronous multi-frequency multi-element cooperative differential common-view 'common-threshold' comparison intelligent-control phase-locked loop + the cellular star-shaped strip static crossing 2 × 50km × 20-2000 km transmission realized by two groups of three optical routes of the '0-level clock group' and another '0-level clock group' of 2000km in the invention. The availability of each time frequency reference node is better than 99.999996%. Therefore, the cloud platform of the optical fiber support network basically does not need to consider the requirement of time keeping

The time frequency reference node of the invention has high precision, and hierarchical 'operation and maintenance automation' management:

(A) the 'operation and maintenance automation' management of the 'O-level clock group': monitoring telemetry and remote control returns is performed only over a "level 1 clock group" of five large areas, including the backup "level 1 clock group" above the HPRTC nodes;

(B) the 'operation and maintenance automation' management of the 'level 1 clock group': the operation and maintenance automation management of PRTC nodes in each province and city is only carried out for the PRTC nodes in the large area: monitoring, telemetering and remote control are only realized on LPRTC nodes in province and city;

(C) the method comprises the following steps of 'operation and maintenance automation' management of LPRTC nodes in various cities: monitoring, telemetering and remote control are realized only for county centers and partial important terminal users within the local city range;

the main event contents of the hierarchical operation and maintenance automation management are as follows:

(A) the slave station clock returns to the corresponding master station active discovery function verification;

(B) marginal performance (threshold) warning of important parts (components);

(C) the key fault event automatically generates a function of printing an operation and maintenance work order;

an HPRTC (high Performance real time clock) 1-level clock group is formed by two hydrogen atomic clocks and three cesium atomic clock structures, is assumed to be called as a 1-level clock group, and is called as an HPRTC standard time frequency reference node, wherein the time frequency accuracy and the stability of the 1-level clock group are better than 1E to 15/day; the Slave node is a Master node of the regional center of the national '0-level' backbone network, and is a Slave (Slave) node of the national '0-level clock group', but is also the Master node of the regional center where the Slave node is located. How to accurately pass the ultra-high precision time-frequency reference to the (cesium atomic clock) PRTC node of the large area?

PRTC is a time frequency reference node (Master of '1-level' and '2-level' time frequency) formed by two cesium atomic clocks and two rubidium clocks. Is generally arranged in a provincial center and automatically traces to the HPRTC.

LPRTC-a time frequency reference node (Slave node of a 2-level backbone network and Master node of a 3-level synchronization network) consisting of two rubidium clocks; typically in a metro level center.

DCXO RTC-county center node, each synchronized with corresponding local city LPRTC node

﹡ set A, B, C, D, E, F + O (center node);

﹡ sets the highest-ranked clock group of the O node clock nodes, and the slave clock node of A, B, C, D, E, F is a one-level lower clock than the A station;

﹡, the optical transmission optical path 50km of O → A, O → B, A → B, O → C, B → C, O → D, C → D, O → E, D → E, O → F, E → F, F → A is controlled to have the same (virtual) delay value (or set to have a nominal value of Txk code of T2.0K code, i.e. 2kHz 500000.000ns) and random noise variation < 5 ps/day, i.e. the length distance error is controlled to: less than 1 mm. (< 5ps)

﹡ assumes that the frequency stability and accuracy of the master clock (HPRTC clock group) is 1E-15/day, from the O1 master station selecting 1330nm and 1290nm equal delay light wavelength pairs simultaneously in phase to transmit the time frequency reference to the slave station a1 in normal transmission, since the two light waves are transmitted to 0 → a by the same optical route at the same starting time of the same optical fiber. The value of the propagation delay Toa of O → A according to the intrinsic characteristic 1330nm of the light wave of optical transmission is Ttoa +. DELTA.D, and 1290nm is Ttoa-DELTA.D

﹡ static cross-transfer of 1270nm and 1350nm or 1330nm and 1290nm, which is 2X50km from O → B → A and O → E → A, is that the dispersion slope error of two light waves is compared with the multi-frequency multi-element differential common vision 'common threshold' to intelligently control the phase lock, because the dispersion slope error of 2X50km after static cross-over is accumulated

It is very minor, and theoretical calculations show that when one path is < +2ps, the other path must be < -2 ps. And the delay transmission rule is always transmitted in a differential mode due to the random drift change of the delay caused by the inherent characteristics of the optical wave transmission when the optical route is matched with the transmission, so that the lambda 1270nm and the lambda 1350nm or the lambda 1350nm of the two optical waves of the COPY (Eo (t) taking the reference rising edge of the master station time frequency reference as the optical route or the master station time frequency reference is used as the reference rising edge_1290nmAnd λ_1330nmThe following are selected according to actual conditions:

the matching pairing transmission and static cross compensation of the equal delay optical wave pair depend on the fact that different optical waves have small difference even if the equal delay optical waves have small difference, and the dispersion coefficient and the dispersion slope of the equal delay optical waves are opposite to each other and change in the range of 2x50km so that the dispersion drift accumulation adaptive equalization compensation can be carried out in the transmission process when the temperature slowly changes, so that the dispersion drift accumulation adaptive equalization compensation is carried out in the range of 2000 km.

(1) Definition of "loosely coupled" intelligent phase lock: an important specification of PLL and DPLL phase locked loop is equivalent to 3dB noise bandwidth: the intelligent variable equivalent 3dB noise bandwidth intelligent optimization software is designed under the measurement scale of 0.9ps time interval, so that the phase frequency discrimination zero-crossing detection can obtain better relative frequency reference precision, but PLL (phase locked loop) cannot be cascaded in a loop, and DPLL (digital phase locked loop) zero-distance intelligent control phase locking can obtain excellent synchronization effect.

Is one of the technical measures for improving the accurate intelligent control phase locking technology

The ultra-high stability and accuracy (1E-16/day) can be 1PPS, i.e. the observation and measurement time is 10000 seconds per second compared with one time

And DCXO and VCXO can be selected from 100PPS (100Hz) observation measurement time of 100 seconds to 1000PPS (1KHz) observation measurement time of 10 seconds or more.

The selection principle is as follows:

in the formula

Is the number of observation measurement cycles per 10 to 10000 seconds;

is a cumulative measurement value measuring 10000 NPPS signals.

The Txk code with the unified dimension of 100PPS interval and 100HZ and 10.000000000ms is the t0.1k code.

Example (b):

the core of single-fiber bidirectional cellular star-shaped strip transmission 2x50km static cross compensation transmission is determination of Txk codes, the Txk codes are accurate control of transmission stability and drift accumulation swing performance of each optical route of each 1600 km-2000 km optical fiber in the unified dimension of L (x, y, z) T (t) and T (f), G.652 optical fibers select 2x50km multi-frequency multi-element differential common threshold comparison of 1270nm and 1350nm or 1290nm and 1330nm equal delay wave pairs, namely slope change of positive and negative dispersion coefficients during optical fiber transmission is utilized to form transmission with 1310nm zero dispersion central point, the transmission is started and ended as difference rule, and N x2x50km multi-frequency multi-element differential common threshold comparison is intelligently controlled phase-locked scale Eo (t) to ensure 1600 km-2000 km transmission level.

The "threshold" is the control threshold of "O → F → A (2 x50 km) Tao1 of 1350nm and O1 → B → A (2 x50 km) Tao2+ the third optical fiber O1 → A1 using the same direction 2x 2 unlocking of dual optical waves of 1290nm and 1330 nm", which is to make Eo (t) fall at each moment in the vicinity of the 1/2 central point of the differential common view Tie (t) max and Tie (t) min, namely on both sides of the threshold of the "common threshold", namely two equal delay optical waves are transmitted through the first optical fiber 1270nm5km, at the moment, the A1 point has two groups of differential common comparison points, namely two "threshold" central points Eo1(t) and Eo2(t), and the intelligent optimization scaling algorithm Eo (t) is weighted according to the majority of cooperative decision, because the four multiple-element differential common point common view "is also processed by multiple frequency intelligent optimization, the simulation measurement in a laboratory is less than 'ps grade', so the theoretical calculation is as follows: 1/2 "ps order" center point. For example, the ultra-high precision time frequency reference of 1E-16/day of the '0 level clock group' of Xian can be accurately transmitted to Beijing and mutually synchronous comparison with the 'common threshold' of multiple differential common view can be realized by the '0 level clock group' of Beijing. In fact, how to achieve the ultra-high precision time frequency reference of the "O-level clock group" of the west ampere "to" zoom out "by 50km to synchronize a DCXO ultra-low phase noise output is exactly the same as the technology of" zero "distance DCXO" loose coupling "master-slave synchronization, that is, in the case of O → a1 which is stepped from the cellular star strip, 2 × 25km O → B → a and 0 → F → a is 2 × 50km, 1270nm and 1350nm, and 1350nm and 1270nm are selected to reach an a node (DCXO) to share three optical routes:

setting the drift of the temperature change of 50km of a square circle with a point 0 as the center to +2 ℃/day, the drift value of the day of 50km1350nm is 2 ℃ multiplied by 50km x (+)3.07ps/nm.km. degree C. +307ps/nm, and the drift accumulation of the day of 1270nm is-3.07 ps/nm.km multiplied by 2 ℃ multiplied by 50 km-307 ps/nm, the error of the two optical waves is determined by the error introduced by the relative deviation of the two optical waves from the nominal optical wave

Similarly, the two pairs of 1270nm and 1350nm/1330nm and 1290nm of the three optical fibers are compared by a honeycomb star-shaped strip transmission multi-frequency multi-element difference common threshold, and Eo (t) is transmitted to a time service center of the Xian country to realize mutual synchronization. If the conditions are sufficient, Beijing → Jingjiu line Xinxiang → Zhengzhou → xi ' an honeycomb star-shaped band multi-frequency multi-component difference commonly-viewed ' common threshold ' comparison can be increased, so that the accurate, stable and high-level time precision transmission of the ' 0-level clock group ' ultra-high precision time frequency standard is guaranteed.

Xi ' an → 8 x2x50km ← Taiyuan → 4 x2x50km ← Shi jia pressure → 4 x2x50km ← Beijing honeycomb star ribbon fiber multi-frequency multi-difference common ' threshold ' comparison intelligent control phase locking

5.1g.652 optical cable zero dispersion 1310nm as the center of the equal time delay light wave (for example 1290nm and 1330nm or 1270nm and 1350nm) transmitted light wave equal time delay transmission multi-frequency multi-element difference common view "common threshold" comparison intelligent control phase locking +2 × 50km static cross optical route matching transmission mode, intelligent control phase locking technology, unity: the unified representation technical indexes of the time and the frequency period are as follows:

the synchronization precision is 1GHz-100MHz-10 MHz;

unified time synchronization of 100MHz-10 MHz-1 Hz;

10000 PPS-100 PPS-1 PPS time precision Txk code multi-frequency multi-element common view 'common threshold' comparison phase discrimination special chip design;

the unified Txk code is a normalized and standardized time interval code stream, and if the code is equivalent to a P code (50PPS or 100PPS) of a GPS and the like, the length of a nominal delay value of an optical fiber can reach 3000 km.

The requirement that the nominal value of 50km is not the true value T4.0k of the fiber length in A → ← B two places requires that the nominal value of the design is 51.06762487km (the delay value corresponding to the optical route is 250.000000 μ s) and that the nominal value of 4.0KHz code is 4000.000000000Hz Time interval error (TID-Time lnterval development) < xps, i.e., the Time interval period is 250.000000 μ s

Since T (t) T (f) and L (x, y, z) are unified by Txk codes to unify the alignment measurement and the common view alignment accuracy to unify the three time-frequency light waves COPY, the monitoring calibration fiber L (x, y, z) (coefficient dimension of fiber length changing with temperature xps/km. ℃) is controlled by only one dimension to constantly transmit from Tx → Rxx to the start and end of the optical route by a plurality of combinations of 2000km to 20000km or more, and one Txk code, for example, 2 × 50km, that is, M × 2 × 50km, 2000km to 20000km or 2 × Nkm km at a plurality of distances below, may be unified

In the mx 2 × Nkm, N is 20, 25, 32, 40, 50, 64, 80, 100, 160, 200 … …, etc. to form a 2000km to 20000km optical fiber transmission network.

L-2 × Nkm-2 Txk the nominal length is set to 2 × 50km if the distance between the actual lengths of the optical fibers of two city-level city optical routes is about 90km from 2 × Nkm, for example A, B in M, and the center 1/2 is about 45km, and L (x, y, z) -Txk code 4.000000000000kHz cycle 250.000000 μ s.

The ideal design scheme of 2 multiplied by 50km, 4 multiplied by 2 multiplied by 50km, 8 multiplied by 2 multiplied by 50km and … … multiplied by 2 multiplied by 50km has the advantages that the standardization and the normalization are consistent to be one Txk code, the operation and maintenance automation is easy to realize, the operation and maintenance cost is low, and the maintenance work is very convenient.

Why the optical route of the G.652 cable fiber is selected to be 2X50km mode instead of 2X 100km

The Rms drift value of an optical route of a 50km optical repeater when the temperature changes by 1 ℃ is as follows: 774ps, and assuming that the temperature variation of the 1000km optical fiber line is basically uniform, the peak-peak daily drift corresponding to 1 ℃ Rms drift Σ i2 ═ 20 × 774ps ═ 15.48ns ≈ 44ns according to 50km × 20 optical repeaters 1000km optical fiber line is 2 √ 2 × 15.48ns ≈ 44 ns. The LD device is about 0.17ns drift (Rms is sigma 0.054ns), which is the drift amplitude of single optical wave transmission with temperature change. The effects of segmenting, stripping, compressing and filtering six kinds of randomly-changed drift accumulated noise transmitted by an optical fiber by using the loopback 'on-line monitoring' optical fiber time delay servo locking and accurate control technology of the MRT main station are as follows:

the '0-level clock group' 1E-16/day national backbone transmission cellular star-shaped strip-shaped multi-element cooperative difference common view simultaneous comparison phase locking technical indexes are as follows:

master-slave synchronization effect of "level 1 clock group" 1E-15/day: 5E-16/day;

master-slave synchronization effect of provincial central PRTC: 1E-15/day;

master-slave synchronization effect of city center LPRC: 5E-15/day;

5.2 equal time-delay optical wave pair centered at 1550.12nm zero dispersion, e.g. λ, also in G.653 cable transmission_1552.12nmAnd λ_1548.11nmThe multi-component difference of the light wave to the multi-frequency is commonly viewed as the 'common threshold' comparison lambda_1552.12nmAnd λ_1548.91nmAnd λ_1552.93nmAnd λ_1548.11nm… …, etc. are also automatic compensation for the inherent characteristics of optical fiber transmission in transmission by using mirror symmetry equal-delay light waves at both sides of the zero dispersion center of the optical fiber, and the dispersion slope at both sides of the center point is better if the value of the dispersion coefficient at the zero dispersion center point of G.653 is 0.9ps/nm.km, and if the value is the same as G.652, the DWDM transmission effect is better.

The quasi-delayed optical wave with non-zero dispersion and displaceable dispersion center (such as 1520nm and 1500nm with 1510nm as zero dispersion center) to multi-frequency multi-component differential co-view "common threshold" comparison intelligent phase-lock is similar to G.652. However, the two optical transmission performances are different, so the intelligent control method has some difference.

The static crossing of the difference wave pair group of the wave band of the 5.4G.652 optical cable fiber S, C, L also has the functions of dividing, stripping, compressing and filtering the multi-frequency multi-element differential common 'threshold' comparison intelligent control phase lock. Reference is made to the previous implementation, but the effect is worse than 0 band equal time delay optical wave pair transmission. The filtering effect is also poor.

5.5 eliminating and compressing mismatching transmission errors of optical route Tx → Rx and return Tx → Rx, reducing these asymmetric difference value, zero crossing detection method Txk code < 100 ps-5 ps, multi-frequency multi-element cooperation common view common threshold comparison technique important link

5.6 laboratory simulation honeycomb star-shaped ribbon transmission fiber multi-frequency multi-element differential common view 'common threshold' comparison intelligent control phase locking 'ps-level' synchronous precision experimental demonstration and verification: the magnitude of the random noise occurring being mainly due to the optical fibre

5.6.1 laboratory simulation 4 x2x50km or 8 x2x 100km star-shaped zonal equal-delay single-fiber bidirectional differential common view 'common threshold' comparison transmission experiment;

5.6.2 Beijing → 2x50km ← Baoding → 2x50km ← Shijia presses honeycomb star belt-shaped isochronal delay single fiber bidirectional multi-frequency multi-component difference commonly look at the "common threshold" to compare and transmit demonstration engineering construction;

comparing an intelligent control phase-locking experimental verification and a Western-Ann → Taiyuan demonstration engineering experimental verification by using an 8 multiplied by 2 multiplied by 50km laboratory simulation honeycomb star-shaped ribbon optical fiber single-fiber bidirectional equal-time-delay multi-frequency multi-element differential common-view 'common threshold';

5.6.4eHPRTC → PRTC → eHPRTC mutually-synchronous honeycomb star-shaped ribbon fiber single-fiber bidirectional multi-frequency multi-element differential co-vision "common threshold" comparison intelligent control phase-locking demonstration engineering experiment construction;

the invention has the beneficial economic and technical effects that:

(1) time-frequency reference of "ps order":

the invention relates to a precise time service technology (method) for multi-frequency multi-difference common view transmitted by honeycomb star-shaped ribbon fibers, which aims to realize comparison of a common threshold:

firstly, the high-precision time frequency reference source (the comparison error with the UTC time is not considered) of the O class clock group of 1E-16/day of the O point passes through the place beyond 2000km without error.

(2) The biggest difficulty of the 'ps-level' transmission is the negative influence of multiple random variation noises of optical fiber transmission, the servo locking and precise control technology of MRT plus 'on-line monitoring' optical fiber time delay is used for strengthening the segmentation, stripping, compression and filtering of the multiple random variation noises, and the multiple random variation noises are converted into the 'ps-level' normal distribution function noise distribution rule of the 'stable random process', and the method is also one of the most key technologies

(3) The second key technology of Eo (t) < 5ps is realized by comparing the equal time delay optical wave pair + static crossing (2 x50km or other) honeycomb star-shaped ribbon optical fiber single-fiber bidirectional multi-frequency multi-element differential common 'threshold' comparison with the self-adaptive dispersion drift accumulation equilibrium compensation, the compression and the filtered optical route double-group initial-final differential common 'common threshold' comparison.

(4) The accuracy and stability of the time frequency reference of the two master station '0-level clock groups' are 1E-16/day, the time frequency reference is transmitted to the '1-level clock group' time frequency reference nodes of three optical routes which realize 'ps-level' mutual synchronous comparison and main → slave synchronous cellular star-shaped transparent, stable, accurate, safe and robust transmission, and the realization of differential common view simultaneous comparison is the third key technology.

(5) The random variation noise of the optical fiber along with the temperature variation is a key factor of the ultra-high precision time frequency reference transmission error. There are also many other random variation noises and drift accumulation in the optical wave transmission in the optical fiber, and it is also necessary to precisely control the various random variation noises of the optical fiber. Therefore, when the optical fiber transmits extremely precise time frequency, it is necessary to completely divide, distance, compress and filter out various random variation noises generated by the optical fiber transmission.

(6) The development of a special chip with ultra-precise 'timestamp' and proprietary intellectual property rights is four of the key technologies.

(7) The ps-level optical fiber transmission matched with the ultra-precise tail fiber product and the ultra-low phase noise output system ensures that phi (t) random variation noise is not increased.

(8) The third step can be completed by two steps: firstly, a method for realizing multistage cascade of a sub-ns-level synchronization technology with zero-distance loosely-coupled intelligent-control phase-locked less than or equal to +/-500 ps to +/-200 ps is carried out, and then ps-level synchronization is completed;

for example: a laboratory simulation verification experiment with the volume of 4 multiplied by 2 multiplied by 50km less than or equal to +/-200 ps:

comparing and transmitting an emulation measurement experiment verification by using a 4 multiplied by 2 multiplied by 50km optical fiber 1270nm and 1350nm optical wave single-fiber bidirectional cellular star-shaped multi-band multi-component differential common vision 'common threshold';

4X 2X50km 1270nm and 1350nm and 1330nm and 1290nm co-directional transmission laboratory simulation measurement experiments:

experimental verification of the implementation of the M1 × 2 × 50km and M2 × 2 × 100km cellular star-shaped ribbon differential transmission multivariate "multipoint normalization" common view "common threshold" comparison technology.

When the MRT master station loops back + "on-line monitoring" + optical fiber delay servo phase lock and precise control make the Tx → Rx real transmission delay value of each optical fiber standardized by Txk code and normalized by 2 × 100km optical fiber delay value, i.e. L (x, y, z) distance (can be regarded as a unified Txk code virtual verification value Tao), the time interval period (Tao) is the same as the period (Tao) corresponding to 10KHz to 1Hz after 10MHz synchronous frequency division, i.e. a variation function is used to represent the three, the control of three random variation noises is also realized by intelligently controlling the precision of a dimension, therefore, the ultra-high precision "clock group" honeycomb ribbon star transmission is shown in fig. 1:

(a) setting HPRTC as '1-level' atomic clock group (frequency stability and accuracy of 1E-15/day), MRT master station loopback 'on-line monitoring' + optical fiber time delay servo locking and precise control can reach less than or equal to 86.4 ps/day

(b) The PRTC automatically traces from a high-level '1-level clock group', and the filtering effect of various random variation noises for segmenting and stripping an optical route transmitted by light is basically the same as that of the '1-level clock group';

(c) two cesium atomic clocks of PRTC operate independently or receive an air satellite navigation system and other modes to obtain an air time frequency reference, the optimal synchronization effect is +/-5-1E-14/day, the safety aspect is needless to say, the improvement of the stability and the accuracy of the cesium atomic clock is limited, and the filtering effect of the time delay random variation noise of the divided stripped optical fiber is far from (b)

(d) Obviously, in order to realize the synchronization effect of the ultra-high precision time frequency less than 50 ps/day, a unified time frequency reference optical fiber supporting network platform must be established, and the method is a good method for realizing the multi-frequency multi-element differential common view 'common threshold' comparison intelligent control phase locking technology by using the cellular star-shaped strip-shaped equal time delay optical waves.

The time drift swing amplitude of the time synchronization precision is firmly controlled within +/-10 ns to +/-5 ns to +/-2.5 ns to +/-1.5 ns to +/-100 ps to +/-20 ps by utilizing the MRT master station loopback + 'on-line monitoring' + optical fiber time delay servo locking and precise control technology, after an intelligent control phase-locking compression filtering technology is applied under the condition of noise submergence by adopting a differential multi-frequency multi-element common comparison transmission device of time delay light waves such as optical fibers and the like, the Es (t) point approximately equal to 0 is equivalent to the zero-crossing point of the pendulum in the transmission process, and actually, the zero-crossing point is the point of the virtual mirror image Es (t) point "0", namely es (t) 0 (floor scaling zero) is objectively present along the principle of differential swing > 2000km, the swing principle of the '0' point of Es (t) can be completely realized by only using an intelligent control technology to accurately control the swing symmetry so as to further ensure that the time synchronization precision reaches +/-1 ns to +/-500 ps to +/-100 ps to +/-25 ps to +/-5 ps.

(9) The specific inherent physical characteristics of optical wave transmission in different optical cables such as G.653-G.657 are further researched, and the invention is found to be used in the prior art or used in the prior art after being improved, so that the ps-level synchronization is realized.

Tracking and accurate receiving of a time frequency reference source of 'pulsar' is superior to 1E-18/day 'astronomical clock which is most stable in nature'.

In the light of the optical routing, there is an astronomical clock which is better than 1E-18/day and is the most stable astronomical clock in nature, namely an pulsar which is a dead stellar and is a dead body, the density of the pulsar per cubic centimeter is high up to 10 hundred million tons, and the pulsar rotates by itself for thousands of times per second according to the 'gyro principle': the great quality and the high rotating speed ensure that the pulsar has extremely stable periodicity, and the stability is 10000 times higher than that of the hydrogen atomic clock in the world at present, namely the stability of 1 second to 1E-18/day in 300 hundred million years is achieved.

The earth has an atmosphere layer and an ionized layer of about 1000km, so that transmission damage is large during ground surface receiving and comparing, and the synchronization effect is limited. If a plurality of Txk code time frequency reference signals which realize optical communication synchronization in space vacuum and simultaneously receive the rotation of a gyroscope of a pulsar from 1E to 18/day and a pulsar navigation satellite system which is mutually synchronized and compared are arranged on a 35000km geosynchronous orbit above the earth or in a Beidou fourth generation navigation satellite, the hydrogen atomic clock and the cesium atomic clock in the navigation satellite can realize the synchronization effect of the full vacuum transmission with the pulsar, which is greatly higher than that of any clock group on the earth. And also higher than current airborne GNSS systems.

If the GPS/GLONASS/BDS (Beidou) and the like in the air realize main → multi-element multi-frequency difference common view common threshold comparison synchronization with a pulsar navigation satellite system in the space vacuum, and the frequency stability and the accuracy better than 1E-18/day are realized by the real-time common view common threshold comparison (only comparison verification) with adjacent star numbers, and the clock difference time synchronization is less than or equal to +/-50 ps/day, the possibility is realized.

Claims (3)

1. A multi-component multi-frequency common-view comparison time service method based on a common threshold is characterized in that three or more than three optical routes are adopted as a plurality of time frequency transmission routes participating in common-view comparison, time frequency is transmitted by adopting time interval codes of more than two frequencies, the time from a master station is obtained by selecting an equal delay wavelength pair of an optical fiber O wave band through static cross transmission and is used as the common threshold, and time service for a slave station is realized through common-view comparison;

the specific scheme of using three optical routes as a plurality of time frequency transmission routes for reference and common view comparison is as follows: one optical route transmits 1PPS + TOD, and the other two optical routes are used for transmitting frequency signals with the same frequency;

the static cross transmission adopts a static wavelength cross dispersion compensation method of an O wave band to transmit time;

when the time frequency is transmitted, the intelligent control phase locking technology is used for dividing, stripping, compressing and filtering various randomly changed parasitic noises transmitted by the optical fiber, so that the time delay value of the optical fiber is constantly controlled within an allowed tolerance range;

the three optical routes are transmitted and compared at the same time, and local adjacent clocks or clock groups at the same level also need to have three optical routes to return and transmit to the master station, and the three optical routes are compared with each other and are mostly judged;

the three or more optical routes adopt a honeycomb star-shaped strip topology structure, and the honeycomb star-shaped strip topology structure adopts a regular hexagon star topology unit structure to transmit an optical network, and specifically comprises the following steps:

two optical clocks and at least more than three fountain cesium atomic clock architectures form a 0-level clock group as a national 0-level synchronous Master, mutual synchronous comparison of transmission of a plurality of national 0-level masters > 2000km optical fibers is realized, ultra-high precision time frequency references of more than two 0-level masters are transmitted to an opposite end, a honeycomb star-shaped ribbon topology architecture is adopted to transmit multi-element equal delay light waves, multi-element multi-frequency common view comparison intelligent control lock addition smooth equalization fine adjustment delay compensation is transmitted for differential static crossing 2x Nkm three-time sequence transmission, an original reference threshold of time is compressed to swing at zero point zero crossing, common thresholds are set to four levels of +/-40 ps, +/-20 ps, +/-10 ps and +/-5 ps, and time interval measurement resolution is as follows: 8ps, 4ps, 2ps, 1 ps.

2. The multi-element multi-frequency co-view comparison timing method based on the common threshold as claimed in claim 1, wherein the static cross transmission is: by utilizing the inherent characteristic of optical wave transmission during optical fiber transmission, when the equal-time-delay wavelength pairs at two sides of a zero-dispersion center 1310nm in a G.652 optical cable are subjected to single-fiber bidirectional transmission or simultaneous static cross transmission in the same optical fiber, the dispersion coefficient slopes of two optical waves slowly change along with the temperature and are the inherent regularity that the dispersion coefficient slopes change in a positive-negative difference mode from beginning to end, and the optical fiber dispersion accumulation adaptive compensation is realized by utilizing an intelligent phase-locking technology and a static cross transmission method.

3. The multi-element multi-frequency common-view comparison timing method according to claim 1, wherein the asymmetric difference of the time delay of the optical route is controlled within a range of 20ps to 5 ps.

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