CN109525353A - SDH transmits the method that IEC61588 eliminates non-symmetric error - Google Patents

SDH transmits the method that IEC61588 eliminates non-symmetric error Download PDF

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Publication number
CN109525353A
CN109525353A CN201811620789.5A CN201811620789A CN109525353A CN 109525353 A CN109525353 A CN 109525353A CN 201811620789 A CN201811620789 A CN 201811620789A CN 109525353 A CN109525353 A CN 109525353A
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CN
China
Prior art keywords
symmetric error
code stream
iec61588
symmetric
error
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CN201811620789.5A
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Chinese (zh)
Inventor
许文
管晓权
田永和
刘长羽
叶泂涛
王建鸿
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ZHEJIANG SAISI ELECTRONIC TECHNOLOGY Co Ltd
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ZHEJIANG SAISI ELECTRONIC TECHNOLOGY Co Ltd
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Priority to CN201811620789.5A priority Critical patent/CN109525353A/en
Publication of CN109525353A publication Critical patent/CN109525353A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H04J3/0647—Synchronisation among TDM nodes
    • H04J3/065—Synchronisation among TDM nodes using timestamps
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H04J3/0658—Clock or time synchronisation among packet nodes
    • H04J3/0661—Clock or time synchronisation among packet nodes using timestamps
    • H04J3/0667—Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0682—Clock or time synchronisation in a network by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

The present invention provides the methods that a kind of SDH transmission IEC61588 eliminates non-symmetric error, which comprises the following steps: step S1, level-one PTP master clock pass through Ethernet code stream of the Ethernet transmission comprising PTP protocol message；Ethernet code stream in step S1 is converted to E1 code stream by step S2, protocol conversion apparatus；Step S3, SDH network transmit the E1 code stream in step S2 step by step；E1 code stream in step S3 is converted to Ethernet code stream by step S4, protocol conversion apparatus；Step S5 obtains PTP protocol message, time of the extraction time stamp adjustment from clock from clock from the Ethernet code stream in step S4；Step S6 carries out non-symmetric error compensation to from clock time by non-symmetric error backoff algorithm.The method that SDH transmission IEC61588 disclosed by the invention eliminates non-symmetric error, using SDH transmission network transmission IEC61588 agreement and then is effectively saved cost, improves precision.

Description

SDH transmits the method that IEC61588 eliminates non-symmetric error
Technical field
The present invention relates to Clock Synchronization Technology fields, and in particular to a kind of SDH transmission IEC61588 elimination non-symmetric error Method.
Background technique
IEC61588, also referred to as PTP, in fields such as Industry Control, electric power, mobile communication using more and more extensive, it can be with The wonderful grade of the sub-micro even timing tracking accuracy of nanosecond are provided.In IEC61588 time synchronization protocol, time synchronization protocol Basis is the symmetrical of uplink downlink propagation delay time.If uplink downlink propagation delay time is asymmetric, i.e. t_ms is not equal to t_sm, Comprising asymmetrical error amount in the time deviation then calculated using IEC61588 time synchronization protocol So that time deviation cannot be corrected correctly, the quality of time synchronization is reduced, even resulting in the time basically can not synchronize.? In actual life, communication link is often non complete symmetry, and this is mainly due to the delay of forward and reverse link and queuings The difference of delay.
At present in power industry, IEC61588 is transmitted in the channel SDH and has been widely used.Transmission network Road Diameter is delayed including the link delay between master clock and interchanger, interchanger internal delay time, interchanger and between clock Link delay and transmission link are switched, and especially transmission link channel switching is affected to link, this link change Uncertainty necessarily lead to the asymmetry of link between master-salve clock, when the asymmetry of propagation delay has become solution One significant challenge of clock stationary problem.
Summary of the invention
In order to solve the above technical problems, overcome deficiency in the prior art, a kind of SDH transmission IEC61588 is provided and is disappeared Except the method for non-symmetric error.
Technical solution used by the present invention solves the above problems is: the SDH transmits IEC61588 and eliminates non-symmetric error Method, it is characterised in that: the following steps are included:
Step S1, level-one PTP master clock pass through Ethernet code stream of the Ethernet transmission comprising PTP protocol message；
Ethernet code stream in step S1 is converted to E1 code stream by step S2, protocol conversion apparatus；
Step S3, SDH network transmit the E1 code stream in step S2 step by step；
E1 code stream in step S3 is converted to Ethernet code stream by step S4, protocol conversion apparatus；
Step S5, from clock from step S4 Ethernet code stream obtain PTP protocol message, extraction time stamp adjustment from when The time of clock；
Step S6 carries out non-symmetric error compensation to from clock time by non-symmetric error backoff algorithm.
Further, the protocol conversion apparatus uses E1/Ethernet protocol converter.
Further, the non-symmetric error backoff algorithm saves non-symmetric error using data set, and is stored in non-easy In the property lost storage equipment.
Further, the non-symmetric error backoff algorithm carries out non-symmetric error using GNSS satellite positioning system Assessment and calculating.
Further, the non-symmetric error backoff algorithm matches PTP transmission path using RTD is compared.
Further, the non-symmetric error backoff algorithm characterizes a PTP transmission path, data using data set The non-symmetric error offset including current transmission path, RTD threshold value are concentrated, offset finally uses the time.
The present invention also provides a kind of assessment of non-symmetric error and backoff algorithms, comprising the following steps:
Step S7, the initialization of asymmetric data table；
Step S8, the assessment and calculating of non-symmetric error；
Step S9, the automatic compensation and calibration of non-symmetric error.
Compared with prior art, the invention has the following advantages: being transmitted using existing numerous SDH transmission network IEC61588 agreement, effectively save cost of arranging net, simultaneously because to the automatic assessment of non-symmetric error and intelligence in SDH transmission network It can compensate, the precision of PTP networking is very high.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with It obtains other drawings based on these drawings.
Fig. 1 is the flow diagram that PTP calculates time deviation in the present invention.
Fig. 2 is the schematic diagram that PTP is transmitted in SDH transmission network in the present invention.
Fig. 3 is non-symmetric error backoff algorithm state machine diagram in the present invention.
Fig. 4 is non-symmetric error backoff algorithm Data concentrating composition in the present invention.
Fig. 5 is that non-symmetric error calibrates state flow chart in the present invention.
Fig. 6 is annular networking schematic diagram in the present invention.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is A part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art Every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
A kind of method that SDH transmission IEC61588 eliminates non-symmetric error, comprising the following steps:
Step S1, level-one PTP master clock pass through Ethernet code stream of the Ethernet transmission comprising PTP protocol message；
Ethernet code stream in step S1 is converted to E1 code stream by step S2, protocol conversion apparatus；
Step S3, SDH network transmit the E1 code stream in step S2 step by step；
E1 code stream in step S3 is converted to Ethernet code stream by step S4, protocol conversion apparatus；
Step S5, from clock from step S4 Ethernet code stream obtain PTP protocol message, extraction time stamp adjustment from when The time of clock；
Step S6 carries out non-symmetric error compensation to from clock time by non-symmetric error backoff algorithm.
Preferably, the protocol conversion apparatus uses E1/Ethernet protocol converter.
Preferably, the non-symmetric error backoff algorithm, saves non-symmetric error using data set, and it is stored in non-easy In the property lost storage equipment.
Preferably, the non-symmetric error backoff algorithm, carries out non-symmetric error using GNSS satellite positioning system Assessment and calculating.
Preferably, the non-symmetric error backoff algorithm, matches PTP transmission path using RTD is compared.
Preferably, the non-symmetric error backoff algorithm, a PTP transmission path, data are characterized using data set The non-symmetric error offset including current transmission path, RTD threshold value are concentrated, offset finally uses the time.
The present invention also provides a kind of assessment of non-symmetric error and backoff algorithms, comprising the following steps:
Step S7, the initialization of asymmetric data table；
Step S8, the assessment and calculating of non-symmetric error；
Step S9, the automatic compensation and calibration of non-symmetric error.
Embodiment 1
Referring to attached drawing 1 to Fig. 6, the working principle that the SDH transmission IEC61588 eliminates non-symmetric error method is shown.
Referring to attached drawing 1, if PTP master clock and PTP are inconsistent from the propagation delay time between clock, i.e. t_ms is not equal to t_sm, if Without amendment, by t1, t2, t3, t4 timestamp calculates deviation, then can have non-symmetric error
It is transmitted referring to attached drawing 2, master clock and the PTP protocol message from clock by SDH.Protocol conversion apparatus 220 will The Ethernet code stream of PTP master clock 210 is converted to E1 code stream.Then it is transmitted step by step by SDH transmission network 230.Protocol conversion dress It sets 240 and E1 code stream is converted into Ethernet code stream.PTP from clock 250 according to the message interacted with master clock, when extracting corresponding Between stamp calculate time deviation, finally by non-symmetric error backoff algorithm eliminate non-symmetric error.
Core of the invention first is that PTP from clock by GNSS (global position system) auxiliary system 260 carry out it is non-right Claim the assessment and calculating of error.The GNSS system time is based on UTC time, by comparing PTP from clock according between principal and subordinate Time that timestamp restores and and the deviation of GNSS system time can evaluate the non-symmetric error in current transmission path.
Referring to attached drawing 3, the non-symmetric error backoff algorithm from clock will be illustrated in a manner of state machine.
Starting 300 is to power on and reset when progress, then carries out 310 operation of initialization, initialization is to data Initial configuration, the including but not limited to initialization of GNSS auxiliary system, the setting of bandwidth, the setting etc. of time-out time.
Enter non-symmetric error unknown state 320 after the completion of initialization, exchanges message, GNSS in state PTP master-salve clock Auxiliary system receives star and positions and provide temporal information, but the non-symmetric error under the state is unknown incorrect in other words 's.Enter non-symmetric error run mode 330 after carrying out initial assessment to non-symmetric error, non-symmetric error has been under the state It is evaluated to calculate and compensated to from clock.
Non-symmetric error backoff algorithm is illustrated by detailed below, before illustrating non-symmetric error backoff algorithm, First illustrate the data set used in non-symmetric error backoff algorithm.
Referring to attached drawing 4, non-symmetric error data set 400 includes mainly two parts, and first part is used in the algorithm General data set 401 and N number of non-symmetric error data subset 410,420 for arriving etc..
General data collection 401 includes following data:
(1) master clock CLOCK_ID: being the ID for showing master clock associated with the data set；
(2) path indexing INDEX: the sequence number of currently used asymmetric subset is indicated；
(3) state: current non-symmetric error backoff algorithm state in which (non-symmetric error unknown state, non-symmetric error Run mode, non-symmetric error calibrate state)；
(4) asymmetry compensation value: the offset of current path non-symmetric error.
Non-symmetric error data subset 410,420 ... 440 includes following data:
(1) state value: calibrating when characterizing current data subset, includes following state: not calibrated to complete with calibration；
(2) offset: the offset of current path non-symmetric error；
(3) residual noise: for assessing a probabilistic index for offset；
(4) timestamp finally used: the time of offset in (1) is finally used；
(5) RTD (Round-trip Delay) maximum value, minimum value and average value: the corresponding path of current value The maximum value of delay, minimum value and average value.
Referring to attached drawing 3, under 320 state of non-symmetric error unknown state, there are no the offsets of available non-symmetric error, only Have and evaluate current non-symmetric error, can just exit the state comprising the steps of:
Step S1: initialization non-symmetric error data set.Non-symmetric error data set 400 mentioned above contains N number of non- The data subset of balanced error, if there is with the current matched data set of master clock, current offset will be obtained, if Do not have matched, the state of all data subsets will be set as not calibrated state.Each data subset represents one The path of unique PTP transmission, we correspond to one with path delay RTD (Round-trip Delay) and CLOCK_ID PTP transmission path.
Step S2: current asymmetric data collection is updated.It is first determined whether having and the current path delay matched data of RTD Collection.If the RTD value of i-th of non-symmetric error data set is matched with current RTD value, it just becomes an alternative number According to collection.
Step S3: if finding an alternative data set, need to judge whether alternative data set is effective.If there is one A data set is matched with the RTD value of current path, needs to further confirm that whether the data set is effective.The step needs GNSS The cooperation of auxiliary system, when effectively (satisfaction can receive satellite, in-position holding and time and UTC to GNSS auxiliary system The condition being consistent) after, non-symmetric error backoff algorithm compares the time difference from clock and master clock and assists from clock and GNSS The time difference of system determines whether matched data set is effective.If effectively, into the non-symmetric error run mode 330 of Fig. 3.
Step S4: if not finding alternative data set, non-symmetric error backoff algorithm waits until that GNSS auxiliary system has After effect, calculated under current path from clock with the time difference of GNSS auxiliary system and from the time difference of clock and master clock by calculating Non-symmetric error between principal and subordinate.If be concentrated with and the matched data set of the RTD of current path in N number of non-symmetric error data The data for then updating the data set, if creating new data set without if.It is run after having updated into the non-symmetric error of Fig. 3 State 330.
Referring to attached drawing 3, under the run mode 330 of non-symmetric error, non-symmetric error has calculated and to from Zhong Jinhang The compensation of error will not be to the data of non-symmetric error in this state if exception occurs in the PTP message interaction between principal and subordinate Collection makes update, will not enter non-symmetric error and calibrate state 340.If message interaction is normal between principal and subordinate, can calculate between principal and subordinate RTD and judge whether current data concentrate RTD maximum value and minimum value within the scope of.If being unsatisfactory for condition, It is likely occurred the change of transmission path, needs to recalculate offset, algorithm enters non-symmetric error align mode 340.
It is the flow chart of non-symmetric error calibration state referring to attached drawing 5.When current non-symmetric error does not know (335) When enter non-symmetric error align mode.Such case mostly occurs to break down in the interruption of PTP service, such as PTP master clock, Or transmission path changes.Non-symmetric error calibration process the following steps are included:
Step S1: it waits and to be measured stablizes 510.Due to needing one with calculating to reappraising for new route non-symmetric error The fixed time, therefore while starting, such as needs at the stabilization to be measured.
Step S2: judging whether there is alternative data set in non-symmetric error data set, and it is non-right to be traversed by CLOCK_ID Claim error information collection, judges whether current RTD value meets one that N number of asymmetric data concentrates RTD value range.If full Foot, effectively confirms 530 into alternate data collection, new data set 560 is selected if being unsatisfactory for.
Step S3: alternate data collection effectively confirms 530.The matching of RTD value is not the condition uniquely needed.Because one In a little situations, referring to attached drawing 6, such as certain nodes of a looped network transmission environment, path 630 clockwise and path counterclockwise 640 RTD value is not much different substantially, and application RTD value that cannot be single is judged.Therefore it also needs to assist by GNSS System carries out auxiliary confirmation.When the value and current value that GNSS auxiliary system obtains are inconsistent, assume to survey using Ye Beisi Examination is confirmed the validity.
Step S4: it if not finding matched valid data collection or alternate data collection, needs to select new data set. N number of asymmetric data subset is traversed, finding first state is not calibrated data subset, if it is not calibrated for can not find state Data subset oldest data set is covered according to the timestamp finally used in data set.
Step S5: non-symmetric error 570 is reappraised.It is the calculating and RTD thresholding maximum value and minimum of RTD value first The determination of value.Different values can be set according to different transmission environments, the model of RTD threshold value in shaking bigger environment Enclosing can be relatively larger to meet the worst transmission environment, opposite to shake smaller environment, and the value of RTD thresholding can be with It is smaller.Followed by the non-symmetric error value for calculating current path by GNSS auxiliary system.It is corresponding non-in this process The data of balanced error subset just update completion back to non-symmetric error run mode 550.
It should be pointed out that being above schematical by the detailed description that preferred embodiment carries out technical solution of the present invention And not restrictive.Those skilled in the art can be to recorded in embodiment on the basis of reading description of the invention Technical solution modify or equivalent replacement of some of the technical features, and these are modified or replaceed, not The essence of corresponding technical solution is set to be detached from the range of technical solution of the embodiment of the present invention.

Claims (6)

1. a kind of method that SDH transmission IEC61588 eliminates non-symmetric error, which comprises the following steps:
Step S1, level-one PTP master clock pass through Ethernet code stream of the Ethernet transmission comprising PTP protocol message；
Ethernet code stream in step S1 is converted to E1 code stream by step S2, protocol conversion apparatus；
Step S3, SDH network transmit the E1 code stream in step S2 step by step；
E1 code stream in step S3 is converted to Ethernet code stream by step S4, protocol conversion apparatus；
Step S5 obtains PTP protocol message from clock from the Ethernet code stream in step S4, and extraction time stamp is adjusted from clock Time；
Step S6 carries out non-symmetric error compensation to from clock time by non-symmetric error backoff algorithm.
2. the method that SDH transmission IEC61588 according to claim 1 eliminates non-symmetric error, which is characterized in that described Protocol conversion apparatus uses E1/Ethernet protocol converter.
3. the method that SDH transmission IEC61588 according to claim 1 eliminates non-symmetric error, which is characterized in that described Non-symmetric error backoff algorithm saves non-symmetric error using data set, and is stored on non-volatile memory device.
4. the method that SDH transmission IEC61588 according to claim 1 eliminates non-symmetric error, which is characterized in that described Non-symmetric error backoff algorithm carries out the assessment and calculating of non-symmetric error using GNSS satellite positioning system.
5. the method that SDH transmission IEC61588 according to claim 1 eliminates non-symmetric error, which is characterized in that described Non-symmetric error backoff algorithm matches PTP transmission path using RTD is compared.
6. the method that SDH transmission IEC61588 according to claim 1 eliminates non-symmetric error, which is characterized in that described Non-symmetric error backoff algorithm characterizes a PTP transmission path using data set, includes current transmission path in data set Non-symmetric error offset, RTD threshold value, offset finally use the time.
CN201811620789.5A 2018-12-28 2018-12-28 SDH transmits the method that IEC61588 eliminates non-symmetric error Pending CN109525353A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021255249A1 (en) * 2020-06-18 2021-12-23 Net Insight Ab Link profiling for assymetric delay compensation

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102098155A (en) * 2011-03-18 2011-06-15 北京国智恒电力管理科技有限公司 Method for realizing sub-microsecond synchronization accuracy based on PTP (Precision Time Protocol)
US20140192826A1 (en) * 2013-01-07 2014-07-10 Microsemi Corporation Universal asymmetry compensation for packet timing protocols
CN108155965A (en) * 2017-12-29 2018-06-12 贵州电网有限责任公司 SDH transmits IEC61588 methods

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102098155A (en) * 2011-03-18 2011-06-15 北京国智恒电力管理科技有限公司 Method for realizing sub-microsecond synchronization accuracy based on PTP (Precision Time Protocol)
US20140192826A1 (en) * 2013-01-07 2014-07-10 Microsemi Corporation Universal asymmetry compensation for packet timing protocols
CN108155965A (en) * 2017-12-29 2018-06-12 贵州电网有限责任公司 SDH transmits IEC61588 methods

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021255249A1 (en) * 2020-06-18 2021-12-23 Net Insight Ab Link profiling for assymetric delay compensation

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