CA1338357C - Transmission line switching system - Google Patents
Transmission line switching systemInfo
- Publication number
- CA1338357C CA1338357C CA000592808A CA592808A CA1338357C CA 1338357 C CA1338357 C CA 1338357C CA 000592808 A CA000592808 A CA 000592808A CA 592808 A CA592808 A CA 592808A CA 1338357 C CA1338357 C CA 1338357C
- Authority
- CA
- Canada
- Prior art keywords
- transmission line
- terminal repeater
- transmission
- cable
- repeater
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/74—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission for increasing reliability, e.g. using redundant or spare channels or apparatus
- H04B1/745—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission for increasing reliability, e.g. using redundant or spare channels or apparatus using by-passing or self-healing methods
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
- Small-Scale Networks (AREA)
Abstract
A transmission line switching system for switching a transmission line in operation to another transmission line when a fault occurs in the transmission line during operation comprising: a transmission line in operation constituted by a plurality of terminal repeaters, a plurality of circuit switching apparatuses, and a plurality of transmission cables, all connected in series; and another transmission line provided between a head terminal repeater and an end terminal repeater;
wherein when a transmission cable is completely disconnected, information input from the head terminal repeater is returned from a terminal repeater located just before a disconnection in the transmission cable to the head terminal repeater, transferred from the head terminal repeater to the end terminal repeater through the another transmission line, returned from the end terminal repeater to a terminal repeater located just after the disconnection in the transmission cable, and returned to the end terminal repeater.
wherein when a transmission cable is completely disconnected, information input from the head terminal repeater is returned from a terminal repeater located just before a disconnection in the transmission cable to the head terminal repeater, transferred from the head terminal repeater to the end terminal repeater through the another transmission line, returned from the end terminal repeater to a terminal repeater located just after the disconnection in the transmission cable, and returned to the end terminal repeater.
Description
TRANSMISSION LINE SWITCHING SYSTEM
BACKGROUND OF THE lNV ~:N'l'ION
1. Field of the Invention The present invention relates to a transmis-sion line switching system, particularly, it relates to a transmission line switching system for taking counter-measures against faults occurring in a transmission cable between remote locations (for example, between cities) through a plurality of t~rm; n~ 1 repeaters.
BACKGROUND OF THE lNV ~:N'l'ION
1. Field of the Invention The present invention relates to a transmis-sion line switching system, particularly, it relates to a transmission line switching system for taking counter-measures against faults occurring in a transmission cable between remote locations (for example, between cities) through a plurality of t~rm; n~ 1 repeaters.
2. Description of the Related Art Transmission lines used for data transmission, telephone circuits, and the like are constituted by, for example, an optical fiber cable or a coaxial cable as the transmission cable. Recently, optical fiber cables are widely utilized as a transmission cable due to the high speed and large volume data transmission obtained thereby.
In general, such a transmission cable is constituted by main cables and a spare cable (or cables). The spare cable is used in an emergency and is usually bundled together with the main cables as one transmission cable.
The most frequent type of transmission cable fault is disconnection of the cable, particularly, a complete disconnection of an optical fiber cable. Such a complete disconnection occurs, for example, during construction or when the cable is damaged by flood water, since an optical fiber cable is very thin and is not bendable.
When complete disconnection of the cable occurs, the transmission line must be switched to another transmission line, since the spare cable is also disconnected.
A problem occurs, however, in switching the transmission line, particularly, a transmission line connected by a plurality of terminal repeaters each ~L
having an intermediate relay function, as explained hereinafter.
Regarding transmission line switching systems, Japanese Unexamined Patent Publication (Kokai) No. 54-127615 discloses a switching system of a communication line for effectively utilizing a plurality of spare lines by selecting change-over switches; Japanese Unexamined Patent Publication (KOKAI) No. 59-175224 discloses a transmission line switching system for effectively switching between main lines, and between a main line and a spare line in accordance with the priority of the information; and Japanese Unexamined Patent Publication (KOKAI) No. 62-219720 discloses a transmission line switching system for effectively switching a plurality of spare lines.
Nevertheless, the above documents do not disclose a loop back function according to the present invention.
SUMMARY OF THE INVENTION
A feature of one embodiment of the present invention provides a transmission line switching system enabling a quick switching of a transmission line to another line when a fault, particularly a complete disconnection of the cable, occurs in the transmission line during operation.
In accordance with an embodiment of the present invention there is provided a transmission line switching system for switching a transmission line, connected between a head terminal repeater and an end terminal repeater, comprising: a transmission line connected between the head terminal repeater and the end terminal repeater, and including: a plurality of terminal repeaters, a plurality of circuit switching apparatuses, respectively operatively connected to corresponding ones of the terminal repeaters, and a plurality of transmission cables, respectively connected between a corresponding one of the circuit switching apparatuses and a corresponding one of the terminal repeaters; and another transmission line connected between the head terminal repeater and the end terminal repeater and in parallel with the transmission line; each of the circuit '~
~ 338357 switching apparatuses include: detecting means for detecting if one of the plurality of transmission cables is completely disconnected; and means, responsive to the detecting means, for returning information input from the head terminal repeater to a terminal repeater located just before a disconnection in the transmission cable back to the head terminal repeater, for transferring the information from the head terminal repeater to the end terminal repeater through the another transmission line, for transferring the information from the end terminal repeater to a terminal repeater located just after the disconnection in the transmission cable, and for transferring the information to the end terminal repeater.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
Fig. 1 is a schematic diagram of a conventional transmission line switching system;
Fig. 2 is a schematic diagram of another conventional type transmission line switching system;
Fig. 3 is a schematic diagram of a transmission line switching system according to the present invention;
Fig. 4 is a schematic diagram for explaining a flow of the information in the transmission line having the transmission line switching system shown in Fig. 3 when a fault occurs in the transmission cable;
Fig. 5 is a detailed diagram of the transmission line switching system shown in Fig. 3;
Fig. 6 is a detailed diagram for explaining one connection configuration and flow of the information in a transmission line switching system shown in Fig. 5;
Fig. 7 is a detailed diagram for explaining the other connection configuration and flow of the information in a transmission line switching system shown in Fig. 5; and Fig. 8 is a schematic diagram of one example of the transmission line connected between cities located a great ~,, .
1 33~357 - 3a -distance apart through a plurality terminal repeaters.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Before describing the preferred embodiments, an explanation will be given of a conventional transmission line switching system and the problems thereof.
~,, - - 4 _ l 33835~
Figure 1 is a schematic diagram of a conventional transmission line switching system applied to an optical fiber transmission line. In Fig. l, 40-1 to 40-3 are main cables made of optical fibers and used normally, and 41 is a spare cable also made of an optical cable and used in the case of a fault in the main cable; 42 is an optical fiber transmission cable bundled with the main cables 40-1 to 40-3 and the spare cable 41; 43 and 44 are circuit switching apparatuses each connected to the main cables 40-1 to 40-3 and the spare cable 41, 45 is a control signal for simultaneously switching the circuit switching apparatus 43, 44 from any main cable 40-1 to 40-3 to the spare cable 41 when a fault occurs in a main cable 40-1 to 40-3.
~5 This type of spare cable, however, cannot be used when the transmission cable 42 is completely discon-nected. As explained above, the complete disconnection occurs, for example, during construction or when the cable is damaged by flood water, and much time is required to recover the transmission line.
Figure 2 is a schematic diagram of another conven-tional type transmission line switching system applied to an optical fiber transmission line. In Fig. 2, 10 is the main cable and 11 is the spare cable, 12-1 to 12-n are optical fiber transmission lines, 14'-1 to 14'-n are spare transmission lines, and 15'-1 to 15'-n are terminal repeaters. Each of the spare transmission lines 14'-1 to 14'-n is provided between terminal repeaters 15'-1 to 15'-n for countermeasures against a fault in the main cable. Each of the terminal repeaters 15'-1 to 15'-n has an intermediate relay function (below, intermediate repeater) and can branch the information to an external circuit (not shown). That -~ is, the information can be input (inserted) to or output (derived) from the external circuit as shown by "I"
(insertion) and "D" (derivation).
For example, when the optical fiber cable 12-2 is _ 5 _ 1 3 3 8 3 5 7 completely disconnected, the transmission line is switched to the spare transmission line 14'-2. As is obvious from the above, in a transmission line connected through a plurality of intermediate repeaters, a spare transmission line must be provided between each of the intermediate repe'aters because each repeater has a relay function for branching the information to an external circuit. In this case, it is impossible to provide another transmission line 14' between the terminal 15'-1 and the termin~l 15'-n because each repeater has an intermediate relay function.
To provide a spare transmission line between each of the interme~iate repeaters is very expensive, and accordingly, it is difficult to realize such a trans-mission line switching system at the present time.
Figure 3 is a schematic diagram of a transmission line switching system according to the present invention. In Fig. 3, the current cable 10 is made of an optical fiber and used under normal conditions; 11 is the spare cable made of an optical fiber and used in the case of a fault in the main cable; 12-1 to 12-n are optical fiber transmission lines bundled with the current cable 10 and the spare cable 11; 13 is the transmission line in operation; 14 is another trans-mission line switched from the transmission line 13;
15-1 to 15-n are terminal repeaters; and 16-1 to 16-n are circuit switching apparatuses provided adjacent to each intermediate repeater. The terminal repeaters 15-1 to 15-n, the circuit switching apparatuses 16-1 to 16-n, and the transmission cables 12-1 to 12-n are connected in series in the transmission line 13.
Another transmission line 14 is provided between the head terminal repeater 15-1 and the end terminal -~ repeater 15-n for countermeasures against a fault in the main cable. In this case, a transmission line 14 is already constructed and can be utilized as the other transmission line, as shown in Fig. 8, and accordingly, - 6 -l 338357 it is not necessary to provide a new transmission line as the spare transmission line.
Each of the t~rminAl repeaters 15-1 to 15-n has an intermediate relay function (intermediate repeater) which can branch information to an external circuit.
That is, the infoirmation can be inserted or derived from the external circuit as shown by "I" (insertion) and "D"
(derivation). The above functions are the same as the conventional system.
Further, the circuit switching apparatuses 16-1 to 16-n are provided adjacent to each of the termi nAl repeaters 15-1 to 15-n. Each circuit switching apparatus 16-1 to 16-n has a switching function for switching the connection of the cable, and has a loop back function for returning the signal as explained hereinafter.
Figure 4 is a schematic diagram for explaining the flow of the information in a transmission line having the transmission line switching system shown in Fig. 3 when a fault occurs in the transmission cable. As explained above, each circuit switching apparatus 16-1 to 16-n has a switching function and a loop back function, and accordingly, when the transmission cable 12-k is completely disconnected, the connection of the optical fiber cable is switched in the circuit switching apparatus 16-k and 16-(k+l). The information trans-mitted from the terminAl repeater 15-1 is returned from the switching apparatus 16-k to the circuit switching apparatus 16-1 and sent to the terminal repeater 15-n through another transmission line 14 and the circuit switching apparatus 16-n. The information transmitted to the repeater 15-n is forwarded to the intermediate repeater 15-(k+1) and returned to the terminal repeater ~~ lS-n by the circuit switching apparatus 16-(k+1).
In this case, the information to be returned is selected based on the priority applied to each block of information. That is, the information having a higher _ 7 _ ~ 33 8 3 ~7 priority is connected to the cable having the lower priority in accordance with the priority order.
As is obvious from the above explanation, each of the intermediate repeaters can carry out an intermediate relay function to branch the information to an external circuit even if ain optical fiber transmission cable is completely disconnected, i.e., the information can be inserted into or derived from the external circuit.
Figure 5 is a detailed diagram of the transmission line switching system shown in Fig. 3. In Fig. 5, 29-1 to 29-3 are circuit switching apparatuses for switching the connecting of the cable, and correspond to the circuit switching apparatuses 16-1 to 16-n shown in Figs. 3 and 4; 30-1 and 30-2 are optical fiber cables corresponding to the cables 12-1 to 12-n in Figs. 3 and 4, and are connected in series; 31 is the trans-mission line in operation; 32 is another transmission line corresponding to the line 14 in Figs. 3 and 4; 36-1 to 36-3, 37-1 to 37-5 and 38-1 to 38-3 are circuit switching units provided in each circuit switching apparatus; 34-1 to 34-6 are the main cables used under normal conditions; and 35-1 and 35-2 are the spare cables used in the case of a fault in the main cable.
For example, a conventional optical switch enabling a parallel or cross connection can be utilized for each circuit switching unit 36-1 to 36-3, 37-1 to 37-5 and 38-1 to 38-3. The intermediate repeaters 15-1 to 15-n are not shown in this drawing, to facilitate the explanation.
Figure 6 is a detailed diagram for explaining one connection configuration and flow of the information in the transmission line switching system shown in Fig. 5.
In Fig. 6, the thick solid line denotes the flow of the ~ information when the optical fiber cable 30-1 is completely disconnected. Note, in this case, the spare cable 35-1 also can not be used.
The information input from "IN is switched by the - - 1 3 3 83 ~
switching unit 36-2 and flows to the other transmission line 32 through the switching unit 36-1, the information is next transferred to the spare cable 35-2 of the optical fiber cable 30-2 through the switching units 38-1 and 38-3, and the information is then transferred to the switching unit 37-1 through the switching units 37-3 and 37-5, and the information "OUT"
is obtained through the optical fiber 30-2. As is obvious from "IN~ and "OUT", the transmission line of the output side appears to be the same as that of the input side, and accordingly, the influence of a fault is very slight, even in the case of a complete disconnection.
Figure 7 is a detailed diagram for explaining the other connection cohfiguration and flow of the infor-mation in a transmission line switching system shown in Fig. 5. This is the case where the optical fiber cable 30-2 is completely disconnected. The thick solid line also denotes the flow of the information when the optical fiber cable 30-2 is completely disconnected, and in this case, the spare cable 35-2 also cannot be used.
Note, since the flow of the information is clearly shown by the thick solid lines, the explanation thereof is omitted.
Figure 8 is a schematic diagram of one example of a transmission line, for example, a telephone circuit connected between cities located far from each other, through a plurality of terminal repeaters having the intermediate relay function. The circuit switching apparatuses are provided adjacent to each repeater. The line 13 (between Tokyo and Osaka) is the main trans-mission line. For example, if the transmission line is completely disconnected between Yokohama and Nagoya, the ~ information from Tokyo is sent to Yokohama and returned to Tokyo and transferred to Osaka through Nagano on another transmission line 14, returned to Nagoya, and then transferred to Osaka. Accordingly, the influence 1 33~3~7 g of a fault in the main transmission cable does not affect the transmission of the information.
In the above embodiment, although the explanation is given for an optical fiber type cable, it is possible to apply the present invention to a coaxial type cable.
Further, in 7the above embodiment, since the power source to each terminal repeater is supplied from another power source line, it is not necessary to take into account the influence of a fault based on a complete disconnection of the cable.
In general, such a transmission cable is constituted by main cables and a spare cable (or cables). The spare cable is used in an emergency and is usually bundled together with the main cables as one transmission cable.
The most frequent type of transmission cable fault is disconnection of the cable, particularly, a complete disconnection of an optical fiber cable. Such a complete disconnection occurs, for example, during construction or when the cable is damaged by flood water, since an optical fiber cable is very thin and is not bendable.
When complete disconnection of the cable occurs, the transmission line must be switched to another transmission line, since the spare cable is also disconnected.
A problem occurs, however, in switching the transmission line, particularly, a transmission line connected by a plurality of terminal repeaters each ~L
having an intermediate relay function, as explained hereinafter.
Regarding transmission line switching systems, Japanese Unexamined Patent Publication (Kokai) No. 54-127615 discloses a switching system of a communication line for effectively utilizing a plurality of spare lines by selecting change-over switches; Japanese Unexamined Patent Publication (KOKAI) No. 59-175224 discloses a transmission line switching system for effectively switching between main lines, and between a main line and a spare line in accordance with the priority of the information; and Japanese Unexamined Patent Publication (KOKAI) No. 62-219720 discloses a transmission line switching system for effectively switching a plurality of spare lines.
Nevertheless, the above documents do not disclose a loop back function according to the present invention.
SUMMARY OF THE INVENTION
A feature of one embodiment of the present invention provides a transmission line switching system enabling a quick switching of a transmission line to another line when a fault, particularly a complete disconnection of the cable, occurs in the transmission line during operation.
In accordance with an embodiment of the present invention there is provided a transmission line switching system for switching a transmission line, connected between a head terminal repeater and an end terminal repeater, comprising: a transmission line connected between the head terminal repeater and the end terminal repeater, and including: a plurality of terminal repeaters, a plurality of circuit switching apparatuses, respectively operatively connected to corresponding ones of the terminal repeaters, and a plurality of transmission cables, respectively connected between a corresponding one of the circuit switching apparatuses and a corresponding one of the terminal repeaters; and another transmission line connected between the head terminal repeater and the end terminal repeater and in parallel with the transmission line; each of the circuit '~
~ 338357 switching apparatuses include: detecting means for detecting if one of the plurality of transmission cables is completely disconnected; and means, responsive to the detecting means, for returning information input from the head terminal repeater to a terminal repeater located just before a disconnection in the transmission cable back to the head terminal repeater, for transferring the information from the head terminal repeater to the end terminal repeater through the another transmission line, for transferring the information from the end terminal repeater to a terminal repeater located just after the disconnection in the transmission cable, and for transferring the information to the end terminal repeater.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
Fig. 1 is a schematic diagram of a conventional transmission line switching system;
Fig. 2 is a schematic diagram of another conventional type transmission line switching system;
Fig. 3 is a schematic diagram of a transmission line switching system according to the present invention;
Fig. 4 is a schematic diagram for explaining a flow of the information in the transmission line having the transmission line switching system shown in Fig. 3 when a fault occurs in the transmission cable;
Fig. 5 is a detailed diagram of the transmission line switching system shown in Fig. 3;
Fig. 6 is a detailed diagram for explaining one connection configuration and flow of the information in a transmission line switching system shown in Fig. 5;
Fig. 7 is a detailed diagram for explaining the other connection configuration and flow of the information in a transmission line switching system shown in Fig. 5; and Fig. 8 is a schematic diagram of one example of the transmission line connected between cities located a great ~,, .
1 33~357 - 3a -distance apart through a plurality terminal repeaters.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Before describing the preferred embodiments, an explanation will be given of a conventional transmission line switching system and the problems thereof.
~,, - - 4 _ l 33835~
Figure 1 is a schematic diagram of a conventional transmission line switching system applied to an optical fiber transmission line. In Fig. l, 40-1 to 40-3 are main cables made of optical fibers and used normally, and 41 is a spare cable also made of an optical cable and used in the case of a fault in the main cable; 42 is an optical fiber transmission cable bundled with the main cables 40-1 to 40-3 and the spare cable 41; 43 and 44 are circuit switching apparatuses each connected to the main cables 40-1 to 40-3 and the spare cable 41, 45 is a control signal for simultaneously switching the circuit switching apparatus 43, 44 from any main cable 40-1 to 40-3 to the spare cable 41 when a fault occurs in a main cable 40-1 to 40-3.
~5 This type of spare cable, however, cannot be used when the transmission cable 42 is completely discon-nected. As explained above, the complete disconnection occurs, for example, during construction or when the cable is damaged by flood water, and much time is required to recover the transmission line.
Figure 2 is a schematic diagram of another conven-tional type transmission line switching system applied to an optical fiber transmission line. In Fig. 2, 10 is the main cable and 11 is the spare cable, 12-1 to 12-n are optical fiber transmission lines, 14'-1 to 14'-n are spare transmission lines, and 15'-1 to 15'-n are terminal repeaters. Each of the spare transmission lines 14'-1 to 14'-n is provided between terminal repeaters 15'-1 to 15'-n for countermeasures against a fault in the main cable. Each of the terminal repeaters 15'-1 to 15'-n has an intermediate relay function (below, intermediate repeater) and can branch the information to an external circuit (not shown). That -~ is, the information can be input (inserted) to or output (derived) from the external circuit as shown by "I"
(insertion) and "D" (derivation).
For example, when the optical fiber cable 12-2 is _ 5 _ 1 3 3 8 3 5 7 completely disconnected, the transmission line is switched to the spare transmission line 14'-2. As is obvious from the above, in a transmission line connected through a plurality of intermediate repeaters, a spare transmission line must be provided between each of the intermediate repe'aters because each repeater has a relay function for branching the information to an external circuit. In this case, it is impossible to provide another transmission line 14' between the terminal 15'-1 and the termin~l 15'-n because each repeater has an intermediate relay function.
To provide a spare transmission line between each of the interme~iate repeaters is very expensive, and accordingly, it is difficult to realize such a trans-mission line switching system at the present time.
Figure 3 is a schematic diagram of a transmission line switching system according to the present invention. In Fig. 3, the current cable 10 is made of an optical fiber and used under normal conditions; 11 is the spare cable made of an optical fiber and used in the case of a fault in the main cable; 12-1 to 12-n are optical fiber transmission lines bundled with the current cable 10 and the spare cable 11; 13 is the transmission line in operation; 14 is another trans-mission line switched from the transmission line 13;
15-1 to 15-n are terminal repeaters; and 16-1 to 16-n are circuit switching apparatuses provided adjacent to each intermediate repeater. The terminal repeaters 15-1 to 15-n, the circuit switching apparatuses 16-1 to 16-n, and the transmission cables 12-1 to 12-n are connected in series in the transmission line 13.
Another transmission line 14 is provided between the head terminal repeater 15-1 and the end terminal -~ repeater 15-n for countermeasures against a fault in the main cable. In this case, a transmission line 14 is already constructed and can be utilized as the other transmission line, as shown in Fig. 8, and accordingly, - 6 -l 338357 it is not necessary to provide a new transmission line as the spare transmission line.
Each of the t~rminAl repeaters 15-1 to 15-n has an intermediate relay function (intermediate repeater) which can branch information to an external circuit.
That is, the infoirmation can be inserted or derived from the external circuit as shown by "I" (insertion) and "D"
(derivation). The above functions are the same as the conventional system.
Further, the circuit switching apparatuses 16-1 to 16-n are provided adjacent to each of the termi nAl repeaters 15-1 to 15-n. Each circuit switching apparatus 16-1 to 16-n has a switching function for switching the connection of the cable, and has a loop back function for returning the signal as explained hereinafter.
Figure 4 is a schematic diagram for explaining the flow of the information in a transmission line having the transmission line switching system shown in Fig. 3 when a fault occurs in the transmission cable. As explained above, each circuit switching apparatus 16-1 to 16-n has a switching function and a loop back function, and accordingly, when the transmission cable 12-k is completely disconnected, the connection of the optical fiber cable is switched in the circuit switching apparatus 16-k and 16-(k+l). The information trans-mitted from the terminAl repeater 15-1 is returned from the switching apparatus 16-k to the circuit switching apparatus 16-1 and sent to the terminal repeater 15-n through another transmission line 14 and the circuit switching apparatus 16-n. The information transmitted to the repeater 15-n is forwarded to the intermediate repeater 15-(k+1) and returned to the terminal repeater ~~ lS-n by the circuit switching apparatus 16-(k+1).
In this case, the information to be returned is selected based on the priority applied to each block of information. That is, the information having a higher _ 7 _ ~ 33 8 3 ~7 priority is connected to the cable having the lower priority in accordance with the priority order.
As is obvious from the above explanation, each of the intermediate repeaters can carry out an intermediate relay function to branch the information to an external circuit even if ain optical fiber transmission cable is completely disconnected, i.e., the information can be inserted into or derived from the external circuit.
Figure 5 is a detailed diagram of the transmission line switching system shown in Fig. 3. In Fig. 5, 29-1 to 29-3 are circuit switching apparatuses for switching the connecting of the cable, and correspond to the circuit switching apparatuses 16-1 to 16-n shown in Figs. 3 and 4; 30-1 and 30-2 are optical fiber cables corresponding to the cables 12-1 to 12-n in Figs. 3 and 4, and are connected in series; 31 is the trans-mission line in operation; 32 is another transmission line corresponding to the line 14 in Figs. 3 and 4; 36-1 to 36-3, 37-1 to 37-5 and 38-1 to 38-3 are circuit switching units provided in each circuit switching apparatus; 34-1 to 34-6 are the main cables used under normal conditions; and 35-1 and 35-2 are the spare cables used in the case of a fault in the main cable.
For example, a conventional optical switch enabling a parallel or cross connection can be utilized for each circuit switching unit 36-1 to 36-3, 37-1 to 37-5 and 38-1 to 38-3. The intermediate repeaters 15-1 to 15-n are not shown in this drawing, to facilitate the explanation.
Figure 6 is a detailed diagram for explaining one connection configuration and flow of the information in the transmission line switching system shown in Fig. 5.
In Fig. 6, the thick solid line denotes the flow of the ~ information when the optical fiber cable 30-1 is completely disconnected. Note, in this case, the spare cable 35-1 also can not be used.
The information input from "IN is switched by the - - 1 3 3 83 ~
switching unit 36-2 and flows to the other transmission line 32 through the switching unit 36-1, the information is next transferred to the spare cable 35-2 of the optical fiber cable 30-2 through the switching units 38-1 and 38-3, and the information is then transferred to the switching unit 37-1 through the switching units 37-3 and 37-5, and the information "OUT"
is obtained through the optical fiber 30-2. As is obvious from "IN~ and "OUT", the transmission line of the output side appears to be the same as that of the input side, and accordingly, the influence of a fault is very slight, even in the case of a complete disconnection.
Figure 7 is a detailed diagram for explaining the other connection cohfiguration and flow of the infor-mation in a transmission line switching system shown in Fig. 5. This is the case where the optical fiber cable 30-2 is completely disconnected. The thick solid line also denotes the flow of the information when the optical fiber cable 30-2 is completely disconnected, and in this case, the spare cable 35-2 also cannot be used.
Note, since the flow of the information is clearly shown by the thick solid lines, the explanation thereof is omitted.
Figure 8 is a schematic diagram of one example of a transmission line, for example, a telephone circuit connected between cities located far from each other, through a plurality of terminal repeaters having the intermediate relay function. The circuit switching apparatuses are provided adjacent to each repeater. The line 13 (between Tokyo and Osaka) is the main trans-mission line. For example, if the transmission line is completely disconnected between Yokohama and Nagoya, the ~ information from Tokyo is sent to Yokohama and returned to Tokyo and transferred to Osaka through Nagano on another transmission line 14, returned to Nagoya, and then transferred to Osaka. Accordingly, the influence 1 33~3~7 g of a fault in the main transmission cable does not affect the transmission of the information.
In the above embodiment, although the explanation is given for an optical fiber type cable, it is possible to apply the present invention to a coaxial type cable.
Further, in 7the above embodiment, since the power source to each terminal repeater is supplied from another power source line, it is not necessary to take into account the influence of a fault based on a complete disconnection of the cable.
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A transmission line switching system for switching a transmission line, connected between a head terminal repeater and an end terminal repeater, comprising:
a transmission line connected between the head terminal repeater and the end terminal repeater, and including:
a plurality of terminal repeaters, a plurality of circuit switching apparatuses, respectively operatively connected to-corresponding ones of said terminal repeaters, and a plurality of transmission cables, respectively connected between a corresponding one of said circuit switching apparatuses and a corresponding one of said terminal repeaters; and another transmission line connected between the head terminal repeater and the end terminal repeater and in parallel with said transmission line;
each of said circuit switching apparatuses include:
detecting means for detecting if one of said plurality of transmission cables is completely disconnected; and means, responsive to said detecting means, for returning information input from the head terminal repeater to a terminal repeater located just before a disconnection in the transmission cable back to said head terminal repeater, for transferring the information from the head terminal repeater to the end terminal repeater through said another transmission line, for transferring the information from the end terminal repeater to a terminal repeater located just after said disconnection in the transmission cable, and for transferring the information to the end terminal repeater.
a transmission line connected between the head terminal repeater and the end terminal repeater, and including:
a plurality of terminal repeaters, a plurality of circuit switching apparatuses, respectively operatively connected to-corresponding ones of said terminal repeaters, and a plurality of transmission cables, respectively connected between a corresponding one of said circuit switching apparatuses and a corresponding one of said terminal repeaters; and another transmission line connected between the head terminal repeater and the end terminal repeater and in parallel with said transmission line;
each of said circuit switching apparatuses include:
detecting means for detecting if one of said plurality of transmission cables is completely disconnected; and means, responsive to said detecting means, for returning information input from the head terminal repeater to a terminal repeater located just before a disconnection in the transmission cable back to said head terminal repeater, for transferring the information from the head terminal repeater to the end terminal repeater through said another transmission line, for transferring the information from the end terminal repeater to a terminal repeater located just after said disconnection in the transmission cable, and for transferring the information to the end terminal repeater.
2. A transmission line switching system as claimed in claim 1, wherein each of said terminal repeaters include intermediate relay means for inserting to and deriving from an external circuit the information.
3. A transmission line switching system as claimed in claim 1, wherein each of said transmission cables includes a plurality of main cables and a spare cable bundled with said main cables.
4. A transmission line switching system as claimed in claim 1, wherein each of said transmission cables comprises an optical fiber cable.
5. A transmission line switching system as claimed in claim 1, wherein each of said transmission cables comprises a coaxial cable.
6. A transmission line switching system as claimed in claim 1, wherein each of said circuit switching apparatuses includes switching means for performing a loop back function to return the information to at least one of said head terminal repeater and said end terminal repeater.
7. A transmission line switching system as claimed in claim 1, wherein each of said circuit switching apparatuses is provided adjacent to each of said terminal repeaters.
8. A transmission line switching system as claimed in claim 1, wherein each of said circuit switching apparatuses comprises a plurality of optical switches, each respectively connected to a corresponding one of said transmission cables.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63-055325 | 1988-03-09 | ||
| JP63055325A JPH01228328A (en) | 1988-03-09 | 1988-03-09 | Line switching system for transmission line |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1338357C true CA1338357C (en) | 1996-05-28 |
Family
ID=12995390
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000592808A Expired - Fee Related CA1338357C (en) | 1988-03-09 | 1989-03-06 | Transmission line switching system |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5109296A (en) |
| EP (1) | EP0332199B1 (en) |
| JP (1) | JPH01228328A (en) |
| CA (1) | CA1338357C (en) |
| DE (1) | DE68920459T2 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5313456A (en) * | 1989-03-03 | 1994-05-17 | Fujitsu Limited | Data link protecting system |
| JP2558012B2 (en) * | 1990-11-27 | 1996-11-27 | 富士通株式会社 | Communication line backup method |
| JPH04286230A (en) * | 1991-03-14 | 1992-10-12 | Fujitsu Ltd | Living/spare line switching system |
| JP2528225B2 (en) * | 1991-09-18 | 1996-08-28 | 富士通株式会社 | Transmission line switching method |
| US5365359A (en) * | 1993-05-14 | 1994-11-15 | Catamount Scientific, Inc. | Method for electrically passive self-routing optical multiplexing |
| US5365512A (en) * | 1993-07-02 | 1994-11-15 | Ericsson Ge Mobile Communications Inc. | Multisite trunked RF communication system with reliable control messaging network |
| US5408462A (en) * | 1993-10-07 | 1995-04-18 | Adc Telecommunications, Inc. | Protection switching apparatus and method |
| US5771274A (en) * | 1996-06-21 | 1998-06-23 | Mci Communications Corporation | Topology-based fault analysis in telecommunications networks |
| US5946373A (en) * | 1996-06-21 | 1999-08-31 | Mci Communications Corporation | Topology-based fault analysis in telecommunications networks |
| US6362905B1 (en) * | 1997-02-24 | 2002-03-26 | Hitachi, Ltd. | Optical crossconnect apparatus and optical transmission system |
| JP3854372B2 (en) * | 1997-07-03 | 2006-12-06 | 株式会社日立コミュニケーションテクノロジー | Optical cross-connect device |
| US5887050A (en) * | 1997-05-09 | 1999-03-23 | Siemens Building Technologies, Inc. | Repeater apparatus having isolation circuit |
| US6282169B1 (en) * | 1999-06-11 | 2001-08-28 | Amplify.Net Inc. | Serial redundant bypass control mechanism for maintaining network bandwidth management service |
| DE10041567A1 (en) * | 2000-08-24 | 2002-03-21 | Eichhoff Gmbh | Power supply network has filter arranged inside coupler of redundant medium and low voltage lines of local network transformer stations, to pass high frequency signal and block low frequency signal |
| JP3671868B2 (en) * | 2001-06-07 | 2005-07-13 | 住友金属工業株式会社 | Method for casting high Cr steel |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3882456A (en) * | 1972-01-26 | 1975-05-06 | Nippon Electric Co | Fault-detecting system for a multi-channel relay system |
| US3876983A (en) * | 1974-04-29 | 1975-04-08 | Ibm | Synchronous disconnection and rearrangement |
| US3864533A (en) * | 1973-06-01 | 1975-02-04 | Vidar Corp | Automatic line transfer system and method for a communications system |
| JPS56149851A (en) * | 1980-04-23 | 1981-11-19 | Mitsubishi Electric Corp | Looplike data transmission equipment |
| US4347607A (en) * | 1980-05-09 | 1982-08-31 | Harris Corporation | Voice alarm signalling system |
| US4449247A (en) * | 1980-07-30 | 1984-05-15 | Harris Corporation | Local orderwire facility for fiber optic communication system |
| JPH0614643B2 (en) * | 1983-12-05 | 1994-02-23 | 株式会社日立製作所 | Failure recovery detection method for loop data transmission system |
| US4630268A (en) * | 1984-08-30 | 1986-12-16 | Rockwell International Corporation | Communication circuit loopback test apparatus |
| US4688260A (en) * | 1985-10-09 | 1987-08-18 | Westinghouse Electric Corp. | High-reliability fiber optic repeater |
| JPS62219720A (en) * | 1986-03-20 | 1987-09-28 | Nec Corp | Transmission line switching system |
-
1988
- 1988-03-09 JP JP63055325A patent/JPH01228328A/en active Granted
-
1989
- 1989-03-06 CA CA000592808A patent/CA1338357C/en not_active Expired - Fee Related
- 1989-03-09 EP EP89104219A patent/EP0332199B1/en not_active Expired - Lifetime
- 1989-03-09 DE DE68920459T patent/DE68920459T2/en not_active Expired - Fee Related
-
1991
- 1991-04-29 US US07/698,179 patent/US5109296A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01228328A (en) | 1989-09-12 |
| DE68920459T2 (en) | 1995-06-14 |
| JPH0559617B2 (en) | 1993-08-31 |
| EP0332199A3 (en) | 1991-03-20 |
| EP0332199B1 (en) | 1995-01-11 |
| US5109296A (en) | 1992-04-28 |
| EP0332199A2 (en) | 1989-09-13 |
| DE68920459D1 (en) | 1995-02-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed | ||
| MKLA | Lapsed |
Effective date: 20010528 |