CN103684731B - Method for synchronizing time - Google Patents
Method for synchronizing time Download PDFInfo
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- CN103684731B CN103684731B CN201310229972.3A CN201310229972A CN103684731B CN 103684731 B CN103684731 B CN 103684731B CN 201310229972 A CN201310229972 A CN 201310229972A CN 103684731 B CN103684731 B CN 103684731B
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- time
- time synchronization
- entity
- accuracy
- synchronization
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L7/00—Arrangements for synchronising receiver with transmitter
- H04L7/04—Speed or phase control by synchronisation signals
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L12/40052—High-speed IEEE 1394 serial bus
- H04L12/40091—Bus bridging
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L2012/40267—Bus for use in transportation systems
- H04L2012/40273—Bus for use in transportation systems the transportation system being a vehicle
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
- Small-Scale Networks (AREA)
- Electric Clocks (AREA)
Abstract
The present invention relates to the method for synchronizing time that can implement time synchronization with less amount of information in ethernet communication.The method for synchronizing time of the present invention is as in Ethernet（Ethernet）Implement the method for time synchronization in communication, implementation step includes：（a）Step, from initially supply power to power supply number reach the number K set untill, utilize all entities for participating in time synchronization（Entity）Between the time synchronization information received and dispatched implement time synchronization；（b）Step, during power supply number K+1, using the time accuracy that each entity is judged by the described K times time synchronization information gathered, from the time accuracy, some in the minimum entity of time accuracy is excluded from the time synchronization, and implements the time synchronization.The present invention can be reduced on ethernet communication network as the information of time synchronization transmitting-receiving.
Description
Technical field
The present invention relates to method for synchronizing time, and in particular to implements time synchronization in ethernet communication with small amount information
Method for synchronizing time.
Background technology
Ethernet (Ethernet) is the communication standard using the LAN (LAN) of bus structures mode.Ethernet communication
Communication standard have 802.1 etc..
Time synchronization process is needed when transmitting information using ethernet communication.Time cannot be synchronous, then as vehicle front,
The image display that each camera at rear, left side and right side installation captures is in a picture, each image display picture
Between can time of origin difference.Time of origin difference, can make troubles to driver or user, and provide error message.Drive
Member can also be considered the same image shown with four View four different images.
The time synchronization process of the ethernet communication of 802.1 mode is summarized as follows：With localized network (Local
Network) all entities (Entity) of connection all participate in time synchronization.In ethernet communication in addition to essential information,
Transmitting-receiving is intended to the information of time synchronization between object.One with most accurate clock is selected in the time synchronization information of transmitting-receiving
Entity is provided as GrandMaster can be as the time of other entity benchmark.
The existing time synchronizing method is that all entities all participate in time synchronization in the localized network of ethernet communication
And cause the waste of Internet resources.Especially, existing time synchronizing method is that network is more complicated, the letter received and dispatched for time synchronization
Breath amount can be in that geometry number increases.
The content of the invention
To solve described problem, the present invention provides a kind of entity that GrandMaster is chosen as from physical characteristic under
One time synchronization is also to be chosen as the highest factor of possibility of GrandMaster, is reduced to greatest extent when Ethernet is
Between the information synchronously received and dispatched, to reduce the method for synchronizing time of network occupation rate.
To solve described problem, the present invention provides a kind of method for synchronizing time, and this method is as in Ethernet
(Ethernet) method of interval step, implementation step include when in communicating：(a) step, reaches from power supply number is initially supplied power to
Untill the number K set, the time synchronization information received and dispatched between all entities (Entity) for participating in time synchronization is utilized
Implement time synchronization；(b) step, power number K+1 when, using by described K time gather time synchronization information judge each reality
The time accuracy of body, from the time accuracy, by some in the minimum entity of time accuracy from described
Excluded in time synchronization, and implement the time synchronization.
Preferably, the judgement of the time accuracy is sentenced using the clock frequency (Clock Ration) of the entity
It is disconnected.
Preferably, (b) step is to implement repeatedly, until the entity for being used in the time synchronization becomes two
It is a.
Preferably, the method for synchronizing time includes：(c) step, the time accuracy and before time accuracy it
Between when differing by more than the difference set, when recycling the time synchronization information of entity being finally excluded to implement described
Between it is synchronous.
The beneficial effects of the present invention are can reduce on ethernet communication network as the information of time synchronization transmitting-receiving.
Brief description of the drawings
Fig. 1 is one of the vehicle ethernet communication system for the application time synchronous method for representing the preferred embodiment of the present invention
The diagram of example；
Fig. 2 is the diagram of the first process of the method for synchronizing time for illustrating the preferred embodiment of the present invention；
Fig. 3 is the diagram of the second process of the method for synchronizing time for illustrating the preferred embodiment of the present invention；
Fig. 4 is the diagram of the 3rd process of the method for synchronizing time for illustrating the preferred embodiment of the present invention；
Fig. 5 is the diagram of the 4th process of the method for synchronizing time for illustrating the preferred embodiment of the present invention；
Fig. 6 is the diagram of the 5th process of the method for synchronizing time for illustrating the preferred embodiment of the present invention.
Embodiment
With reference to the accompanying drawings, invention preferred embodiment is described in detail.Reality in description and attached drawing is same
A component is with same symbolic indication, is not repeated to illustrate.And during the explanation present invention, if to related known function or
Illustrating for structure makes present inventive concept thicken, and omits the explanation.
Some component " being connected to " or " being connected in " other components are described, it is possible to be directly connected in or be connected in this its
Its component, but be understood to centre and there may exist other components.On the contrary, describe some component " being directly connected in " or
" being coupled directly to " other components, are understood to centre and other components are not present.
Singulative in this specification, on the premise of not having special suggestion in sentence, also comprising plural form.Explanation
" including (comprises) " for being used in book or " including (comprising) " is not excluded for involved component, step, dynamic
More than one other components, step, action and/or the presence of element or supplement beyond work and/or element.
The method for synchronizing time of the preferred embodiment of the present invention is, from the physical characteristics of oscillating element, when being chosen as becoming
Between synchronization criterion GrandMaster entity (Entity) be chosen as thereafter GrandMaster possibility it is very high, and do not have
There is the possibility that the entity for being chosen as GrandMaster is selected thereafter very low.Therefore the present invention is to utilize this possibility
Property, it is reduced to the information of time synchronization transmitting-receiving and lifts the application degree of Internet resources.The GrandMaster refers to have most clever
The entity of quick temporal information.
The method for synchronizing time of the preferred embodiment of the present invention illustrated in conjunction with the accompanying be can with by vehicle front, after
Side, four cameras in left side and right side installation and the bridge with memory function carry out exemplified by forming ethernet communication system
Illustrate, but be not limited to vehicle communication, the equal available of time synchronization process is needed in ethernet communication.
Fig. 1 is one of the vehicle ethernet communication system for the application time synchronous method for representing the preferred embodiment of the present invention
The diagram of example.According to Fig. 1, vehicle ethernet communication system includes rear camera 110, front camera 120, right side shooting
First 130, left side camera 140, bridge 150 and receiving division 160.
Rear camera 110 is the camera for shooting rear view of vehicle region, and front camera 120 is shooting vehicle front area
The camera in domain.
Right side camera 130 is the camera for shooting vehicle right side region, and left side camera 140 is shooting vehicle left side area
The camera in domain.
Bridge 150 is connect from rear camera 110, front camera 120, right side camera 130 and left side camera 140
It is over to take the photograph image information, as the information for being intended to time synchronization, timestamp (Time Stamp) value of transmitting-receiving hardware or software.
Bridge 150 supports storage to be intended to memory (Memory) function of the information of transmitting-receiving time synchronization.
Bridge 150 and rear camera 110, front camera 120, right side camera 130 and left side camera 140 are real
Time synchronization is applied, receiving division 160 is transmitted to after the shooting image information synthesis that time synchronization is completed.
Receiving division 160 is to receive to complete synchronous composograph information in bridge 150, and receiving division 160 can be audio and video
Network (AVN, Audio Video Network).
The entity (Entity) used in the explanation of the present invention refers to the object that time synchronization is needed on network.In Fig. 1
Rear camera 110, front camera 120, right side camera 130, left side camera 140 and bridge 150 become entity.
Solid line in Fig. 1 between camera and bridge 150 is the image letter that bridge 150 is transmitted in after camera collection
Breath.Dotted line between camera and bridge 150 is the time synchronization information that time synchronization is received and dispatched between entity.
Illustrated below for an example of the method for synchronizing time process of the preferred embodiment of the present invention.In initially power supply K
All entities both participate in time synchronization before secondary.K is that all entities participate in considering synchronous letter in the synchronous process for grasping accuracy
The accuracy and efficiency of breath and the number set.For example, K number is more, it is higher to the accuracy of synchronizing information, but network provides
The application efficiency in source can decline, therefore could be provided as left and right three times.
Bridge 150 is that all entities participate in the statistical value that time synchronizations obtain untill initial power K times, is opened from K+1 times
Begin the entity that power supply each time can exclude to have least accurate clock (Clock) from synchronization.Participate in time synchronization
The process that entity is excluded can implement to the entity for participating in time synchronization there was only one.But it is not the entity for participating in time synchronization
The process being excluded must be implemented to the entity for participating in time synchronization to become one, could be provided as two or three.
Bridge 150 is that the accuracy for continuing the time of the GrandMaster of input since initial power supply is compared.
The time accuracy and essence of existing time of an entity of time synchronization are participated in the process that bridge 150 compares Time precision
Exactness is less than the standard set compared to difference, then time synchronization continues only to utilize an entity.
But bridge 150 participates in the time essence of an entity of time synchronization in the process of the accuracy of relatively time
Difference of the exactness compared with existing time accuracy is more than the standard set, then the entity that can make to exclude recently participates in the time
It is synchronous.When making the entity that excludes recently participate in powering again after time synchronization, if the entity for participating in time synchronization reach one with
On, then bridge 150 can exclude the entity with least accurate clock from time synchronization.And make the entity excluded recently
Participate in time synchronization is powered afterwards next time when similarly, if time accuracy difference compared with existing time accuracy is more than
The standard set, then bridge 150 can make time accuracy secondly high entity participates in time synchronization.
Fig. 2 is the diagram of the first process of the method for synchronizing time for illustrating the preferred embodiment of the present invention.Fig. 3 is to illustrate this hair
The diagram of second process of the method for synchronizing time of bright preferred embodiment.Fig. 4 is to illustrate that the time of the preferred embodiment of the present invention is same
The diagram of 3rd process of one step process.Fig. 5 is the figure of the 4th process of the method for synchronizing time for illustrating the preferred embodiment of the present invention
Show.Fig. 6 is the diagram of the 5th process of the method for synchronizing time for illustrating the preferred embodiment of the present invention.
With reference to Fig. 2 to Fig. 6, the method for synchronizing time of the preferred embodiment of the present invention should by vehicle ethernet communication system
With and the process of implementing time synchronization illustrate.
According to Fig. 2, for the whole participation time synchronizations of all entities untill initial power supply K time, rear camera 110,
Front camera 120, right side camera 130 and left side camera 140 transmit to bridge 150 and the delivery time are gone back outside image information
Synchronizing information.
Bridge 150 judges time accuracy using the time synchronization information received.Specifically, bridge 150 utilizes each entity
Clock frequency (Clock Ratio) judge the accuracy of time.Clock frequency is to utilize the time occurred on software and hardware
Stab (Time-Stamp), the time accuracy of typical hardware is more outstanding than software, therefore can utilize hardware timestamping emphatically.
Fig. 1 is into Fig. 6 with the time accuracy of 0 to 4 five entities of display.Numeral is smaller, and time accuracy is higher, and 4 are
The minimum entity of time accuracy, 0 is the highest entity of time accuracy.
In Fig. 2, counted according to the time synchronization information that bridge 150 receives untill initial power supply three times, bridge 150 can be with
Judge the time accuracy highest of bridge 150, the time accuracy of left and right camera 140 is minimum.
According to Fig. 3, four times power supply when bridge 150 the minimum left side camera 140 of time accuracy in Fig. 2 is same from the time
Excluded in stepping journey.Therefore left side camera 140 and bridge 150 are not required to the time synchronization letter that transmitting-receiving is intended to time synchronization thereafter
Breath.
According to Fig. 4, during five power supplies, the entity that participates in current time synchronization is four entities i.e. rear camera 110, preceding
Square camera 120, right side camera 130 and bridge 150.Than one entity is more.Therefore bridge 150 except in Fig. 3 by the time
Outside the left side camera 140 synchronously excluded, by the minimum right side of time accuracy from four entities for participating in time synchronization
Camera 130 is excluded from time synchronization process.Bridge 150 excluded in time synchronization process on the right side of camera 130, then hereafter
Right side camera 130 and bridge 150 are not required to transmitting-receiving time synchronization information.
According to Fig. 5, the entity that participates in participating in current time synchronization during six power supplies is three i.e. rear camera 110, preceding
Square camera 120 and bridge 150.Than one entity is more.Therefore bridge 150 from three entities for participating in time synchronization by the time
The minimum front camera 120 of accuracy is excluded from time synchronization process.In front of bridge 150 excludes in time synchronization process
Hereafter camera 120, then be not required to transmitting-receiving synchronizing information between bridge 150 and front camera 120.
According to Fig. 6, seven times the entity that current time synchronization is participated in when powering is two i.e. rear camera 110 and bridge
150.Than one entity is more.Therefore bridge 150 from rear camera 110 with the low rear of time accuracy is excluded in bridge 150
Camera 110, only implements time synchronization using the time synchronization information of bridge 150.If the time accuracy of bridge 150 is
1, the time accuracy of rear camera 110 is 0, then 150 time synchronization informations using rear camera 110 of bridge are implemented
Time synchronization.
Bridge 150 judges that implementing time synchronization with an entity can cause accuracy to reduce, then in time synchronization process
The highest entity of time accuracy can be made to participate in time synchronization process from the entity of exclusion.
Specifically, bridge 150 is chosen to be what is recorded in the entity time accuracy and bridge 150 of GrandMaster to plan
The time accuracy in number was compared in the past.Before the time accuracy in number refers to before bridge is stored in number
Highest time accuracy in 150 time accuracy.Therewith, during seven power supplies, the time accuracy in number refers to before
Highest time accuracy during six power supplies.
Time before being chosen as recording in the time accuracy and bridge 150 of the entity of GrandMaster in number
The difference of accuracy is less than the standard set, then selected GrandMaster is still set to GrandMaster, differed greatly
Make time accuracy highest in the standard set, the then entity that bridge 150 can be excluded from time synchronization process
Entity participates in time synchronization process.
The standard set is to can be set as 5 degree of clock frequency, and the setting can be accurate according to what is required in system
Degree, network environment, equipment performance etc. change.
When differing by more than established standards, that is, when judging that the time accuracy of GrandMaster is inaccurate, from the reality of exclusion
The rear camera 110 that the highest entity of time accuracy excludes in nearest time synchronization is set to participate in the time again in body same
Stepping journey.
Bridge 150 is to make rear camera 110 participate in time synchronization process again and implement time synchronization process still sentencing
During disconnected time accuracy inaccuracy, the front camera 120 that time accuracy is high thereafter is set to participate in time synchronization process again.
That is the method for synchronizing time of the preferred embodiment of the present invention is only implemented accurately with an entity as shown in Figure 6
During time synchronization, in terms of the efficiency of network resources for be optimal.But because equipment is outmoded, noise, environment influence etc. sentence
It is disconnected can not only with an entity implement correct time it is synchronous when, make the entity participation time synchronization process excluded one by one
And implement time synchronization process in the form of Fig. 2 to Fig. 5.And first implement time synchronization process then in the form of Fig. 2 to Fig. 5
Implement synchronized process in the form of Fig. 6 again.
It can reduce according to the present invention on ethernet communication network as the information of time synchronization transmitting-receiving.
Above example and attached drawing are merely illustrative of the technical solution of the present invention, rather than its limitations；Although with reference to foregoing
The present invention is described in detail in embodiment, it will be understood by those of ordinary skill in the art that：It still can be to foregoing
Technical solution described in each embodiment is modified, or carries out equivalent substitution to which part technical characteristic；And these are changed
Or replace, the essence of appropriate technical solution is departed from the scope of technical solution described in various embodiments of the present invention.The present invention
Protection domain should be explained according to following rights, and all technical solutions in its equivalents should
Belong to scope of the presently claimed invention.
Claims (2)
1. a kind of method for synchronizing time, the method as the time synchronization in ethernet communication, it is characterised in that the reality of this method
Applying step includes：
(a) step, from initially supplying power to untill power supply number reaches the number K set, using participating in all of time synchronization
The time synchronization information received and dispatched between entity implements time synchronization；
(b) step, power number K+1 when, the time synchronization information utilized by described K time collection judges that the time of each entity is smart
Exactness, from the time accuracy, by some in the minimum entity of time accuracy from the time synchronization
Exclude, and implement the time synchronization,
(b) step is implemented repeatedly, until the entity for being used in the time synchronization becomes one or two,
The method for synchronizing time further includes：
(c) step, the time accuracy and before between time accuracy when differing by more than the difference set, recycle
The time synchronization information of the entity being finally excluded implements the time synchronization, it is described before before time accuracy refers to
The highest time accuracy of time accuracy in number.
2. method for synchronizing time according to claim 1, it is characterised in that
The time accuracy is judged using the clock frequency of the entity.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020120106623A KR101933366B1 (en) | 2012-09-25 | 2012-09-25 | Time Synchronization Method |
| KR10-2012-0106623 | 2012-09-25 |
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| Publication Number | Publication Date |
|---|---|
| CN103684731A CN103684731A (en) | 2014-03-26 |
| CN103684731B true CN103684731B (en) | 2018-04-20 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310229972.3A Active CN103684731B (en) | 2012-09-25 | 2013-06-09 | Method for synchronizing time |
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| Country | Link |
|---|---|
| KR (1) | KR101933366B1 (en) |
| CN (1) | CN103684731B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021147044A1 (en) * | 2020-01-22 | 2021-07-29 | 华为技术有限公司 | Time-sensitive network time synchronization method and apparatus |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101207606A (en) * | 2006-12-18 | 2008-06-25 | 华为技术有限公司 | Method and apparatus for main clock selecting |
| CN102263631A (en) * | 2011-08-10 | 2011-11-30 | 瑞斯康达科技发展股份有限公司 | Method and clock node for determining master clock within 1588 clock domain |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100308704B1 (en) | 1996-07-04 | 2001-10-19 | 모리시타 요이찌 | Multiplexed data producing apparatus, encoded data reproducing apparatus, clock conversion apparatus, encoded data recording medium, encoded data transmission medium, multiplexed data producing method, encoded data reproducing method, and clock conversion method |
| US20080175275A1 (en) * | 2007-01-22 | 2008-07-24 | Samsung Electronics Co., Ltd. | Time synchronization method between nodes in network and apparatus for implementing the same |
-
2012
- 2012-09-25 KR KR1020120106623A patent/KR101933366B1/en active IP Right Grant
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- 2013-06-09 CN CN201310229972.3A patent/CN103684731B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101207606A (en) * | 2006-12-18 | 2008-06-25 | 华为技术有限公司 | Method and apparatus for main clock selecting |
| CN102263631A (en) * | 2011-08-10 | 2011-11-30 | 瑞斯康达科技发展股份有限公司 | Method and clock node for determining master clock within 1588 clock domain |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103684731A (en) | 2014-03-26 |
| KR101933366B1 (en) | 2018-12-28 |
| KR20140039853A (en) | 2014-04-02 |
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