JP2542629B2 - Optical repeater monitoring circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical repeater monitoring circuit having a loopback function.

[Conventional technology]

In the optical submarine relay system, locating a fault point is an important issue for system operation. Therefore, in optical submarine repeaters, the loopback method is generally adopted because the circuit and system configuration is simple. This is because, for example, an optical repeater selection signal is sent from one of both end stations through the uplink to form a loop for each designated optical repeater, and a failure occurs from the state of the signal returned via the downlink. It is intended to locate a certain section of.

FIG. 2 shows a configuration example of a conventional optical repeater. In the figure, the optical repeater has two regenerative repeaters 1-U (for upstream) and 1-D (for downstream) in order to perform bidirectional transmission. These regenerators each contain the same functional elements, of which regenerator 1-
Taking U as an example, an O / E converter (optical / electrical converter) 3-U, a regeneration circuit 4-U, and an E / E converter are provided as regeneration relay functions.
It is equipped with an O converter (electrical / optical converter) 5-U, and for loopback monitoring, command demodulation circuit 7-U, command identification circuit 8-U, repeater number identification circuit 9-U, AND gate. It has circuits 10-U, 11-U, SR flip-flop circuit 15-U, optical shutter drive circuit 16-U, optical shutter 17-U, and optical branch circuit 6-U.

When forming a loopback in the optical repeater configured as described above, for example, a loopback command having the identification number of the regenerative repeater 1-U is transmitted from the terminal station to the transmission line 2-.
Send out via U. In this case, in the regenerative repeater 1-U, the loopback command output 19-U of the command identifying circuit 8-U and the output 20-U of the repeater number identifying circuit 9-U.
Both become H level, and the output of the AND gate circuit 10-U also becomes H level. As a result, the output Q of the SR flip-flop circuit 15-U becomes H level, the optical shutter drive circuit 16-U opens the optical shutter 17-U, and the optical branch circuit 6-U is opened.
The optical signal branched by is returned to the O / E converter 3-D of the opposite regeneration repeater 1-D.

On the contrary, when releasing the loopback, when the loopback release command is sent from the terminal station, in the regenerative repeater 1-U, the loopback command output 19-U of the command identification circuit 8-U becomes the L level, and the loopback command is output. Back release command output 18-U and repeater number identification circuit 9-U output 20
-U both become H level, and SR flip-flop circuit 1
The output Q of 5-U becomes L level. As a result, the optical shutter 17-U is closed and the loopback is released.

[Problems to be solved by the invention]

Generally, in addition to the loopback function, the repeater monitoring function has various monitor functions such as a received power monitor, an LD bias monitor, and a transmitted power monitor. Therefore, it is used in the near-end measurement state, that is, the loopback state. Therefore, these monitor commands are sent in the loopback state. These monitor commands and loopback cancellation commands
A loopback command other than a regenerative repeater in a loopback state is caused by (1) human error in the transmitting terminal station, (2) device malfunction in the transmitting terminal station, and (3) distortion on the transmission path. In that case, a closed loop will be formed due to loopback.

This will be specifically described with reference to FIG.
Now, it is assumed that the terminal station 21 sends a loopback command to the regenerator Rj-U to form a loop 24. next,
Rj-U loopback release command or Rj-U, Rj
Various monitor commands will be sent to -D. However, if these commands become loop commands of the regenerator Rj-D due to the causes shown in (1) to (3) above, the loop 23 will be Since it is formed, the regenerators Ri-U to Rj-I,
A closed loop 25 including Ri-D to Rj-D and the loops 23 and 24 is formed. In such a state, since the signal from the terminal station 21 and the signal in the closed loop 25 are simultaneously input to the regenerator Ri-U, the signal from the terminal station 21 input to the regenerator Ri-U is input. Since the monitoring command does not propagate to the repeaters after the regeneration repeater Ri-U, this closed loop 25 cannot be released. This state also occurs when operated from the terminal station 22.

[Means for solving problems]

An optical repeater monitoring circuit according to the present invention has a command identifying circuit and a repeater number identifying circuit, which identifies a command by these circuits to monitor the operation and which locates a fault point by a loopback function. In the monitoring circuit,
A circuit is provided for canceling the loopback of the own repeater by the output of the command identifying circuit and the repeater number identifying circuit when the loopback command of the other repeater is received.

Example of Invention

FIG. 1 is a block diagram showing the configuration of an embodiment of an optical repeater to which the present invention is applied. In this figure, the regenerator 1'-U has an AND gate circuit 12-U, an inverter circuit 13-U, and an OR gate circuit 14-U, as compared with the conventional regenerator 1-U shown in FIG. There is a difference in the added points. Of course, other regenerators including the regenerator 1'-D are also constructed in the same manner as 1'-D. In this example, the normal loopback formation and loopback release operations are the same as those described with reference to FIG. However,
According to the circuit configured as described above, when the loopback command of the other regenerator is received, the loopback command output 19-U of the command identification circuit 8-U is at the H level,
The output 20-U of the repeater number identification circuit 9-U becomes L level, but since there is the inverter circuit 13-U, the AND gate circuit 12
-U output is H level, SR flip-flop circuit 15-U
Output Q becomes L level, and the loopback is released. That is, in this circuit, the loopback is released by both the loopback release command and the loopback command of the other regenerator.

This will be explained with reference to FIG.
When the terminal station 21 mistakenly sends a regenerator Ri-D loopback command during formation, the loop 23 is formed, but at the same time, the loop 24 is released as described above, so the closed loop 25
Is not tied.

〔The invention's effect〕

As apparent from the above description, according to the present invention,
It is possible to prevent the formation of a closed loop by canceling the loopback of the local repeater when the loopback command of another repeater is received, and it is possible to obtain a large effect to improve the reliability of the fault location. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an optical repeater to which the present invention is applied, FIG. 2 is a block diagram showing a configuration example of a conventional optical repeater, and FIG. 3 is a terminal station and an optical repeater. It is a system diagram which shows the relay system which connects with. In this figure, 1'-U and 1'-D are regenerators, 2-U and 2-
D is a transmission line, 3-U is an O / E converter, 4-U is a regeneration circuit, and 5-U
Is an E / O converter, 6-U is an optical branch circuit, 7-U is a command demodulation circuit, 8-U is a command identification circuit, 9-U is a repeater number identification circuit, 10-U, 11-U, 12 -U is an AND gate circuit, 13-U is an inverter circuit, 14-U is an OR gate circuit, 15-U is an S / R flip-flop circuit, 16-U is an optical shutter drive circuit, 17-U
Is an optical shutter, and 21 and 22 are terminal stations.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shu Yamamoto 2-23 Nakameguro, Meguro-ku, Tokyo Inside the International Telegraph and Telephone Corporation (72) Inventor Hiroharu Wakabayashi 2-chome, Nakameguro, Meguro-ku, Tokyo No. 1-23 Inside the Institute of International Telegraph and Telephone Corporation (56) Reference JP-A-58-190138 (JP, A) JP-A-58-195346 (JP, A) JP-A-58-138146 (JP, A)

Claims (1)

(57) [Claims] 1. An optical repeater monitoring circuit having a command identifying circuit and a repeater number identifying circuit, which identifies a command by these circuits and monitors the operation, and which locates a fault point by a loopback function, An optical repeater monitoring circuit, which is provided with a circuit for canceling the loopback of its own repeater by the output of the command identifying circuit and the repeater number identifying circuit when a loopback command of another repeater is received.