CN102917284A - Precise clock synchronization method based on PON (Passive Optical Network) system - Google Patents
Precise clock synchronization method based on PON (Passive Optical Network) system Download PDFInfo
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- CN102917284A CN102917284A CN2012104049624A CN201210404962A CN102917284A CN 102917284 A CN102917284 A CN 102917284A CN 2012104049624 A CN2012104049624 A CN 2012104049624A CN 201210404962 A CN201210404962 A CN 201210404962A CN 102917284 A CN102917284 A CN 102917284A
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Abstract
The invention provides a precise clock synchronization method based on a PON system. The precise clock synchronization method comprises an optical line terminal OLT and an optical network distribution unit ONU, wherein the optical line terminal OLT supports that time synchronization information is input in an IRIG-B (InterRange Instrumentation Group-B) code manner from an external standard reference time source; and the method comprises the following steps of: (1) after round-trip times (RTT) of the OLT and the ONU are measured by a system, sending the RTT and configuration information of the RTT to the corresponding ONU by an user-defined OAM (operation, administration and maintenance) extension protocol frame, wherein a difference value between the count value of TIMER at an OLT end and the count value of TIMER at an ONU end is RTT/2; (2) starting eth_en enabling of the OLT end to enable the OLT end to send a time information frame, periodically acquiring current localtime count values during a rising edge period of a start code of the irig-b code at a local end by the OLT, and simultaneously sending the localtime count values and the corresponding time information to the ONU through a user-defined Ethernet data frame; (3) obtaining local time count values corresponding to a next second by the ONU based on the localtime count values and the RTT of the local end according to Tn+1'=Tn-(RTT/2+delta(c))+delta(1s); and (4) outputting the time synchronization information in a manner of pps+tod, wherein under the condition that the pps_en and tod_en at the ONU end are enabled, if the time frame broadcasted by the OLT end is not received, the ONU end enters an automatic time keeping state.
Description
Technical field
What the present invention relates to is that a kind of power communication industry is based on the Method for precise time synchronization between Ethernet passive optical network.
Background technology
Along with the electric power digital development, the NTP(network to the time agreement) error range be 10-100ms, although network application is ripe and convenient, its precision is difficult to reach requirement.Along with the fast development of electric power system, day by day urgent to the requirement of time synchronized, need accurate, safe and reliable clock source, for all kinds of operational outfits of electric power system provide the precise time benchmark.
Summary of the invention
The object of the invention is to overcome the deficiency that prior art exists, and provide a kind of based on the PON system, it can satisfy in the PON network each equipment to the requirement of time synchronized, guarantee the real-time data acquisition time consistency, improve the line fault range finding, phasor and the monitoring of merit angular motion attitude, the accuracy of unit and electrical network parameter verification, thereby improve the level of power grid accident analysis and stable control, improve operation of power networks efficient and reliability, adapt to the large Power System Interconnection of China, the growth requirement of UHV transmission, simultaneously also standard interconnected with by time service equipment or system of clock synchronization system, interconnected and clock synchronization system networking and operational mode between the different manufacturers time synchronism apparatus.
The objective of the invention is to finish by following technical solution, it mainly comprises:
The one optical line terminal OLT terminal equipment of fiber optic backbone (be used for connect) and an optical-fiber network allocation units ONU(send Ethernet data with broadcast mode), described optical line terminal OLT support from external reference time source (PRC) with IRIG-B code form synchronizing information input time; Described Method for precise time synchronization is taked following steps:
1) system by self-defined OAM Extended Protocol frame, sends to corresponding ONU to RTT and configuration information OLT and ONU are measured two-way time (RTT) afterwards, and the difference of OLT end TIMER and ONU end TIMER count value is RTT/2;
2) eth_en of unlatching OLT end enables, make the OLT end can the transmission time information frame, OLT periodically obtains current localtime count value constantly at the rising edge of local terminal irig-b code initial code, and localtime count value and corresponding temporal information are sent to ONU by self-defined ethernet data frame simultaneously;
3) ONU according to Tn+1 '=Tn-(RTT/2+ Δ c)+Δ 1s, obtains localtime count value corresponding to next second based on local terminal localtime count value and RTT; When the localtime count value arrives this value, ONU output pulse per second (PPS) and ToD, wherein, Tn+1 ' is ONU side localtime count value corresponding to next second; Tn is the corresponding OLT side of current pulse per second (PPS) localtime count value; △ c is the time-delay that whole precision clock system produces; Δ 1s is the corresponding ONU side of 1 duration in second localtime count value;
4) ONU with time synchronization information with the pps+tod formal output; In the situation that ONU end pps_en and tod_en enable, if do not receive the time frame of OLT end broadcasting, then the ONU end enters from punctual state.
Self-defined OAM Extended Protocol frame of the present invention is as shown in the table:
Self-defined Ethernet data frame format of the present invention is as shown in the table:
The present invention provides a kind of unified time reference for the equipment at different levels of PON system in the electrical network, its network to the time precision can reach the us level, have high-precision distributed network to the time characteristics, its precision can reach digital communication service to the requirement of clock synchronous.
The OLT of PON system end is by the external clock source, synchronous each ONU of whole system, and ONU end output synchronised clock information, precision reaches more than delicate grade, meets powerline network equipment fully to the requirement of clock accuracy; Electric power serial port time message standard is satisfied in TOD output, and 1200bit/s is to 19200bit/s for the baud rate scope.
Description of drawings
Fig. 1 is TOD system architecture diagram of the present invention.
Embodiment
The present invention will be described in detail below in conjunction with accompanying drawing: shown in Figure 1, and a kind of Method for precise time synchronization based on the PON system of the present invention, it mainly comprises:
The one optical line terminal OLT terminal equipment of fiber optic backbone (be used for connect) and an optical-fiber network allocation units ONU(send Ethernet data with broadcast mode), described optical line terminal OLT support from external reference time source (PRC) with IRIG-B code form synchronizing information input time; Described Method for precise time synchronization is taked following steps:
1) system by self-defined OAM Extended Protocol frame, sends to corresponding ONU to RTT and configuration information OLT and ONU are measured two-way time (RTT) afterwards, and the difference of OLT end TIMER and ONU end TIMER count value is RTT/2;
2) eth_en of unlatching OLT end enables, make the OLT end can the transmission time information frame, OLT periodically obtains current localtime count value constantly at the rising edge of local terminal irig-b code initial code, and localtime count value and corresponding temporal information are sent to ONU by self-defined ethernet data frame simultaneously;
3) ONU according to Tn+1 '=Tn-(RTT/2+ Δ c)+Δ 1s, obtains localtime count value corresponding to next second based on local terminal localtime count value and RTT; When the localtime count value arrives this value, ONU output pulse per second (PPS) and ToD, wherein, Tn+1 ' is ONU side localtime count value corresponding to next second; Tn is the corresponding OLT side of current pulse per second (PPS) localtime count value; △ c is the time-delay that whole precision clock system produces; Δ 1s is the corresponding ONU side of 1 duration in second localtime count value;
4) ONU with time synchronization information with the pps+tod formal output; In the situation that ONU end pps_en and tod_en enable, if do not receive the time frame of OLT end broadcasting, then the ONU end enters from punctual state.
Self-defined OAM Extended Protocol frame of the present invention is as shown in the table:
Self-defined Ethernet data frame format of the present invention is as shown in the table:
Claims (2)
1. Method for precise time synchronization based on the PON system, it mainly comprises:
The one optical line terminal OLT terminal equipment of fiber optic backbone (be used for connect) and an optical-fiber network allocation units ONU(send Ethernet data with broadcast mode), described optical line terminal OLT support from external reference time source (PRC) with IRIG-B code form synchronizing information input time; Described Method for precise time synchronization is taked following steps:
1) system by self-defined OAM Extended Protocol frame, sends to corresponding ONU to RTT and configuration information OLT and ONU are measured two-way time (RTT) afterwards, and the difference of OLT end TIMER and ONU end TIMER count value is RTT/2;
2) eth_en of unlatching OLT end enables, make the OLT end can the transmission time information frame, OLT periodically obtains current localtime count value constantly at the rising edge of local terminal irig-b code initial code, and localtime count value and corresponding temporal information are sent to ONU by self-defined ethernet data frame simultaneously;
3) ONU according to Tn+1 '=Tn-(RTT/2+ Δ c)+Δ 1s, obtains localtime count value corresponding to next second based on local terminal localtime count value and RTT; When the localtime count value arrives this value, ONU output pulse per second (PPS) and ToD, wherein, Tn+1 ' is ONU side localtime count value corresponding to next second; Tn is the corresponding OLT side of current pulse per second (PPS) localtime count value; △ c is the time-delay that whole precision clock system produces; Δ 1s is the corresponding ONU side of 1 duration in second localtime count value;
4) ONU with time synchronization information with the pps+tod formal output; In the situation that ONU end pps_en and tod_en enable, if do not receive the time frame of OLT end broadcasting, then the ONU end enters from punctual state.
2. the Method for precise time synchronization based on the PON system according to claim 1 is characterized in that described self-defined OAM Extended Protocol frame is as shown in the table:
Described self-defined Ethernet data frame format is as shown in the table:
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103997383A (en) * | 2014-05-17 | 2014-08-20 | 北京中和卓远科技有限公司 | Method and device for improving IRIG-B time code decoding precision |
| CN104219037A (en) * | 2013-05-30 | 2014-12-17 | 鼎点视讯科技有限公司 | Time synchronization method, device and system for optical fiber line termination equipment |
| WO2016045340A1 (en) * | 2014-09-23 | 2016-03-31 | 深圳市中兴微电子技术有限公司 | Clock synchronization method, optical network unit and storage medium |
| CN107135045A (en) * | 2017-05-16 | 2017-09-05 | 国家电网公司 | The transformer station's adaptive network and its clock synchronous safety method detected based on difference |
| CN111431886A (en) * | 2020-03-19 | 2020-07-17 | 北京东土科技股份有限公司 | Ethernet communication system, method, device and medium for implementing Ethernet communication |
| CN113993009A (en) * | 2020-07-27 | 2022-01-28 | 上海诺基亚贝尔股份有限公司 | Method and device for multi-domain transmission by time synchronization, OLT and ONU |
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| CN101577600A (en) * | 2008-05-09 | 2009-11-11 | 华为技术有限公司 | Time synchronization method, system and optical network equipment for passive optical network system |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104219037A (en) * | 2013-05-30 | 2014-12-17 | 鼎点视讯科技有限公司 | Time synchronization method, device and system for optical fiber line termination equipment |
| CN103997383A (en) * | 2014-05-17 | 2014-08-20 | 北京中和卓远科技有限公司 | Method and device for improving IRIG-B time code decoding precision |
| WO2016045340A1 (en) * | 2014-09-23 | 2016-03-31 | 深圳市中兴微电子技术有限公司 | Clock synchronization method, optical network unit and storage medium |
| CN107135045A (en) * | 2017-05-16 | 2017-09-05 | 国家电网公司 | The transformer station's adaptive network and its clock synchronous safety method detected based on difference |
| CN107135045B (en) * | 2017-05-16 | 2019-01-25 | 国家电网公司 | Substation's adaptive network and its clock synchronous safety method based on difference detection |
| CN111431886A (en) * | 2020-03-19 | 2020-07-17 | 北京东土科技股份有限公司 | Ethernet communication system, method, device and medium for implementing Ethernet communication |
| CN111431886B (en) * | 2020-03-19 | 2020-11-13 | 北京东土科技股份有限公司 | Ethernet communication system, method, device and medium for implementing Ethernet communication |
| CN113993009A (en) * | 2020-07-27 | 2022-01-28 | 上海诺基亚贝尔股份有限公司 | Method and device for multi-domain transmission by time synchronization, OLT and ONU |
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