JP3010804B2 - Dependent synchronization method - Google Patents
Dependent synchronization methodInfo
- Publication number
- JP3010804B2 JP3010804B2 JP3183662A JP18366291A JP3010804B2 JP 3010804 B2 JP3010804 B2 JP 3010804B2 JP 3183662 A JP3183662 A JP 3183662A JP 18366291 A JP18366291 A JP 18366291A JP 3010804 B2 JP3010804 B2 JP 3010804B2
- Authority
- JP
- Japan
- Prior art keywords
- station
- stations
- free
- clock signal
- clock
- Prior art date
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- Time-Division Multiplex Systems (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、同期ディジタル伝送網
の前提となる網同期方式に利用する。特に、ＳＤＨ多重
化信号のように階層化されたフレームフォーマットの多
重化信号中にある特定の２局間を結ぶパスの監視情報を
含むことによりそのパス上で経由する複数の局間での伝
送路障害をパスの両端の２局間で検知することが可能
で、さらに２局間のクロック周波数差をスタッフ・デス
タッフ制御等によりある程度吸収可能な伝送網に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a network synchronization system which is a premise of a synchronous digital transmission network. In particular, by including, in a multiplexed signal of a layered frame format such as an SDH multiplexed signal, monitoring information of a path connecting a specific two stations, transmission between a plurality of stations via the path is included. The present invention relates to a transmission network capable of detecting a path failure between two stations at both ends of a path and capable of absorbing a clock frequency difference between the two stations to some extent by stuff / destuff control or the like.
【０００２】[0002]
【従来の技術】図２で、局Ｂは局Ａから受信する複数の
ディジタル信号を多重化した多重化信号から伝送クロッ
ク成分を抽出し、それに同期したクロックを生成するこ
とにより局Ａに従属同期している。局Ｃは局Ｂから受信
する複数のディジタル信号を多重化した多重化信号から
伝送クロック成分を抽出し、それに同期したクロックを
生成することにより局Ｂに従属同期している。このよう
にして局Ａ、Ｂ、Ｃの従属同期が確立される。いま、局
Ａから局Ｂに送出されていた多重化信号の伝送路に障害
か発生すると局Ｂは従属すべき抽出クロックが得られな
くなるが、局Ｂから局Ｃへの伝送路は正常なので、局Ｃ
は局Ｂに従属同期したままになる。この状態では局Ｃの
周波数精度は局Ｂの自走精度によって決定される。2. Description of the Related Art In FIG. 2, a station B extracts a transmission clock component from a multiplexed signal obtained by multiplexing a plurality of digital signals received from the station A and generates a clock synchronized with the transmission clock component. are doing. The station C is subordinately synchronized with the station B by extracting a transmission clock component from a multiplexed signal obtained by multiplexing a plurality of digital signals received from the station B and generating a clock synchronized with the transmission clock component. In this way, the slave synchronization of the stations A, B and C is established. Now, if a failure occurs in the transmission path of the multiplexed signal sent from the station A to the station B, the station B cannot obtain the extracted clock to be subordinated, but since the transmission path from the station B to the station C is normal, Station C
Remains dependent on station B. In this state, the frequency accuracy of the station C is determined by the self-running accuracy of the station B.
【０００３】[0003]
【発明が解決しようとする課題】このような従来例で
は、ある局が自走状態になるとその局に従属する下位の
局の周波数精度が自走状態の局の周波数精度により決定
されるので、網を構成する際には局の規模によらず上位
の局では高精度な周波数精度を実現する必要があった。In such a conventional example, when a station enters a self-running state, the frequency accuracy of a lower station subordinate to the station is determined by the frequency accuracy of the self-running station. When constructing a network, it was necessary to realize high-precision frequency accuracy in a higher-order station regardless of the scale of the station.
【０００４】本発明は、このような欠点を除去するもの
で、下位局への影響を考えて上位局の周波数精度を上げ
る必要がなく比較的安価に同期網を構成できる従属同期
方式を提供することを目的とする。The present invention eliminates such disadvantages, and provides a slave synchronization system which can form a synchronization network at relatively low cost without having to increase the frequency accuracy of the upper station in consideration of the influence on the lower station. The purpose is to:
【０００５】[0005]
【課題を解決するための手段】本発明は、従属接続され
た複数個の局で構成され、この複数個の局のそれぞれ
は、自走クロックを発生する自走クロック信号発生部を
備え、下位局のそれぞれは、その上位側の局のそれぞれ
から送出されるディジタル信号を多重化した多重化信号
からこの上位側の局の最上位の局の自走クロック信号を
抽出するクロック抽出部、このクロック抽出部が抽出す
るクロック信号または自走クロック信号のいずれか一方
のクロック信号を選択する選択部、この選択部に選択指
令を与える制御部、およびこの選択手段で選択されたク
ロック信号に応じて自局の同期クロックを発生する同期
クロック発生部を備えた従属同期方式において、上記制
御部は、上記複数個の上位局から送出される多重化信号
に含まれるディジタル信号のうち所定の上位局と自局と
の間の通信に使用されているディジタル信号を抽出し、
この抽出されたディジタル信号に異常が検出された場合
に上記自走クロック信号を選択する選択指令を自局の選
択部に与える手段を備えたことを特徴とする。SUMMARY OF THE INVENTION The present invention comprises a plurality of cascaded stations, each of which includes a free-running clock signal generator for generating a free-running clock. Each of the stations includes a clock extraction unit that extracts a free-running clock signal of the highest-order station of the higher-order station from a multiplexed signal obtained by multiplexing digital signals transmitted from each of the higher-order stations. A selection unit that selects either the clock signal extracted by the extraction unit or the free-running clock signal, a control unit that gives a selection command to the selection unit, and a clock signal selected by the selection unit. In a slave synchronization system having a synchronization clock generation unit for generating a synchronization clock for a station, the control unit includes a digital signal included in a multiplexed signal transmitted from the plurality of upper stations. Extracting a digital signal that is used for communication between a given host station and the own station among the signals,
When an abnormality is detected in the extracted digital signal, there is provided a means for giving a selection command for selecting the self-running clock signal to a selection unit of the own station.
【０００６】[0006]
【作用】多重化されたディジタル信号のうち予め定めた
局と自局との間の通信に使用されているディジタル信号
に異常が検出された場合に自局におけるクロック抽出を
停止して、自走クロック信号を同期部に与える。これに
より、上位局の自走時の周波数精度が下位局の周波数精
度より優れていなければならないという制限が撤廃され
る。When an abnormality is detected in a digital signal used for communication between a predetermined station and the own station among the multiplexed digital signals, the clock extraction in the own station is stopped and the self-running is stopped. A clock signal is provided to the synchronization unit. This eliminates the restriction that the frequency accuracy of the higher-order station during self-run must be superior to the frequency accuracy of the lower-order station.
【０００７】[0007]
【実施例】以下、本発明の一実施例について図面を用い
て説明する。図１は本発明の従属同期方式を用いた場合
の一例として３つの局Ａ、Ｂ、Ｃで同期網を構成した場
合の構成図である。この実施例は、図１に示すように、
従属接続された複数個の局Ａ、ＢおよびＣで構成され、
この複数個の局Ａ、ＢおよびＣのそれぞれは、自走クロ
ックを発生する自走クロック信号発生部１を備え、下位
局ＢおよびＣのそれぞれは、その上位側の局のそれぞれ
から送出されるディジタル信号を多重化した多重化信号
からこの上位側の局の最上位の局の自走クロック信号を
抽出するクロック抽出部２、このクロック抽出部２が抽
出するクロック信号または自走クロック信号のいずれか
一方のクロック信号を選択する選択部３、この選択部３
に選択指令を与える制御部４、およびこの選択手段４で
選択されたクロック信号に応じて自局の同期クロックを
発生する同期クロック発生部５を備え、さらに、本発明
の特徴とする手段として、制御部４は、上記複数個の上
位局Ａ、ＢおよびＣから送出される多重化信号に含まれ
るディジタル信号のうち所定の上位局と自局との間の通
信に使用されているディジタル信号を抽出し、この抽出
されたディジタル信号に異常が検出された場合に自走ク
ロック信号を選択する選択指令を自局の選択部３に与え
る手段を備える。An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram in a case where a synchronous network is formed by three stations A, B, and C as an example when the slave synchronization system of the present invention is used. This embodiment, as shown in FIG.
A plurality of cascaded stations A, B and C,
Each of the plurality of stations A, B, and C includes a free-running clock signal generating unit 1 that generates a free-running clock, and each of the lower stations B and C is transmitted from each of the upper stations. A clock extracting unit 2 for extracting a free-running clock signal of the highest-ranked station from the multiplexed signal obtained by multiplexing the digital signals; and a clock signal or a free-running clock signal extracted by the clock extracting unit 2. A selector 3 for selecting one of the clock signals;
And a synchronous clock generating unit 5 for generating a synchronous clock of the own station in accordance with the clock signal selected by the selecting unit 4. Further, as means characterized by the present invention, The control unit 4 converts a digital signal used for communication between a predetermined upper station and its own station out of digital signals included in the multiplexed signals transmitted from the plurality of upper stations A, B and C. A means is provided for extracting and extracting a selection command for selecting a free-running clock signal to the selector 3 of the own station when an abnormality is detected in the extracted digital signal.
【０００８】次に、この実施例の動作を説明する。局Ｂ
は局Ａから受信した多重化信号から抽出される伝送クロ
ック成分をもとに従属同期を確立しており、局Ｃはクロ
ック抽出部で局Ｂから受信した多重化信号から伝送クロ
ック成分を抽出し、それぞれ従属同期を確立している。
また、局Ｃでは、ディジタル信号監視部で局Ｂから受信
する複数のディジタル信号を多重化した多重化信号の内
から局Ａと局Ｃ間の通信に使用されているディジタル信
号を監視する手段を有する。いま、局Ａと局Ｂとの間の
伝送路に障害が起こったとすると、局Ｃではディジタル
信号監視部で局Ａからの通信に使用されていたディジタ
ル信号を監視しているので、この区間の伝送路に障害が
起こったことを知り、これにより自走した局Ｂの周波数
精度のクロック成分の抽出を停止することができる。し
たがって、局Ｂの自走時の周波数精度は局Ｃに必要な周
波数精度よりも低くできる。すなわち、局Ｂと局Ｃの周
波数精度を制限なく決定できるので、局Ｂ内の網同期装
置を安価にすることが可能になる。Next, the operation of this embodiment will be described. Station B
Has established subordinate synchronization based on the transmission clock component extracted from the multiplexed signal received from station A, and station C extracts the transmission clock component from the multiplexed signal received from station B by the clock extraction unit. , Respectively, have established subordinate synchronization.
In the station C, the digital signal monitoring unit includes means for monitoring a digital signal used for communication between the stations A and C from a multiplexed signal obtained by multiplexing a plurality of digital signals received from the station B. Have. Now, assuming that a fault occurs in the transmission path between the stations A and B, the digital signal monitoring unit of the station C monitors the digital signal used for the communication from the station A. Knowing that a failure has occurred in the transmission path, it is possible to stop the extraction of the clock component with the frequency accuracy of the station B that has been self-propelled. Therefore, the frequency accuracy of the station B during self-running can be lower than the frequency accuracy required for the station C. That is, since the frequency accuracy of the stations B and C can be determined without limitation, the cost of the network synchronization device in the station B can be reduced.
【０００９】[0009]
【発明の効果】本発明は、以上説明したように、ある局
が自走状態になってもその局に従属していた下位の局の
周波数精度は自走状態の局の周波数精度による制限を受
けないので、従来の方式のようにある伝送路での障害の
影響をその局より下位の局に与えないようにするために
周波数精度を高くする必要がなくなる効果がある。As described above, according to the present invention, even if a certain station is in a self-running state, the frequency accuracy of a lower station subordinate to that station is limited by the frequency accuracy of the self-running station. Since it is not affected, there is an effect that it is not necessary to increase the frequency accuracy in order to prevent the influence of a failure on a certain transmission line from affecting a station lower than that station as in the conventional system.
【図１】本発明実施例の構成を示すブロック構成図。FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
【図２】従来例の構成を示すブロック構成図。FIG. 2 is a block diagram showing a configuration of a conventional example.
【符号の説明】 １ 自走クロック信号発生部 ２ クロック抽出部 ３ 選択部 ４ 制御部 ５ 同期クロック発生部[Description of Signs] 1 free-running clock signal generator 2 clock extractor 3 selector 4 controller 5 synchronous clock generator
フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) H04L 3/06 H04L 7/00 H04L 12/00 H04Q 11/00 Continuation of the front page (58) Field surveyed (Int.Cl. 7 , DB name) H04L 3/06 H04L 7/00 H04L 12/00 H04Q 11/00
Claims (1)
この複数個の局のそれぞれは、自走クロックを発生する
自走クロック信号発生部を備え、下位局のそれぞれは、
その上位側の局のそれぞれから送出されるディジタル信
号を多重化した多重化信号からこの上位側の局の最上位
の局の自走クロック信号を抽出するクロック抽出部、こ
のクロック抽出部が抽出するクロック信号または自走ク
ロック信号のいずれか一方のクロック信号を選択する選
択部、この選択部に選択指令を与える制御部、およびこ
の選択部で選択されたクロック信号に応じて自局の同期
タイミングを決定する同期部を備えた従属同期方式にお
いて、 上記制御部は、上記複数個の上位局から送出される多重
化信号に含まれるディジタル信号のうち所定の上位局と
自局との間の通信に使用されているディジタル信号を抽
出し、この抽出されたディジタル信号に異常が検出され
た場合に上記自走クロック信号を選択する選択指令を自
局の選択部に与える手段を備えたことを特徴とする従属
同期方式。1. A system comprising a plurality of stations connected in cascade,
Each of the plurality of stations includes a free-running clock signal generation unit that generates a free-running clock, and each of the lower stations includes:
A clock extraction unit for extracting a free-running clock signal of the highest-order station of the higher-order station from a multiplexed signal obtained by multiplexing digital signals transmitted from each of the higher-order stations. A selector for selecting one of the clock signal and the free-running clock signal, a controller for giving a selection command to the selector, and a synchronization timing of the own station according to the clock signal selected by the selector. In the slave synchronization system having a synchronization unit to be determined, the control unit performs communication between a predetermined upper station and the own station among digital signals included in the multiplexed signal transmitted from the plurality of upper stations. A selection command for selecting a free-running clock signal when a digital signal used is extracted and an abnormality is detected in the extracted digital signal. Dependent synchronization method, characterized in that the method comprises:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3183662A JP3010804B2 (en) | 1991-06-27 | 1991-06-27 | Dependent synchronization method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3183662A JP3010804B2 (en) | 1991-06-27 | 1991-06-27 | Dependent synchronization method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0514300A JPH0514300A (en) | 1993-01-22 |
| JP3010804B2 true JP3010804B2 (en) | 2000-02-21 |
Family
ID=16139738
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3183662A Expired - Fee Related JP3010804B2 (en) | 1991-06-27 | 1991-06-27 | Dependent synchronization method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3010804B2 (en) |
-
1991
- 1991-06-27 JP JP3183662A patent/JP3010804B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0514300A (en) | 1993-01-22 |
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