JP2589322B2 - Optical repeater monitoring circuit - Google Patents

Description

The present invention relates to an optical repeater monitoring circuit having a loopback function.

[Conventional technology]

In an optical repeater system that requires a plurality of optical repeaters, especially in an optical submarine repeater system, fault location is an important problem in system operation. Therefore, the optical submarine repeater generally employs a loopback method because of its simple circuit and system configuration.

In this method, an optical repeater selection signal is transmitted from one of the two end stations via an up line, a loop is formed for each designated optical repeater, and a fault is returned from the state of a signal returned via a down line. The section is to be located.

For this reason, as shown in FIG. 2, in the conventional optical repeater, two regenerative repeaters 1-U for performing bidirectional transmission are used.
(For uplink) and 1-D (for downlink). One of the regenerators has an O / E converter for regenerative relay.
3, a reproduction circuit 4 and an E / O converter 5 are provided. On the other hand, for loopback monitoring, a command demodulation circuit 7, a command identification circuit 8, a repeater number identification circuit 9, AND gate circuits 10, 11, SR F /
It has an F circuit 16, an optical shutter driving circuit 17, an optical shutter 18, and an optical branching circuit 6.

In such an optical repeater, when forming a loopback, when transmitting a loopback command having the identification number of the regenerative repeater from the terminal station, the regenerative repeater 1-U uses the loopback command of the command identification circuit 8 Command output 20
And the output 21 of the repeater number identification circuit 9 becomes H level, and the output of the AND gate circuit 10 also becomes H level. As a result, the output Q of the SR F / F circuit 16 becomes H level, the optical shutter 18 is opened by the optical shutter drive circuit 17, and the optical signal branched by the optical branch circuit 6 is transmitted to the O / E of the opposite reproduction repeater. Return to converter (not shown).

Conversely, when releasing the loopback, when the loopback release command is sent, the regenerative repeater 1-U,
The loopback command output 20 of the command identification circuit 8 is L
Level, the loopback release command output 19 and the output 21 of the repeater number identification circuit 9 both become H level,
As a result, the output Q of the SR F / F circuit 16 becomes L level, the optical shutter 18 is closed by the drive circuit 17, the optical signal branched from the optical branch circuit 6 is cut off, and the loop back is released.

[Problems to be solved by the invention]

By the way, generally, as a repeater monitoring function, in addition to a loopback function, various monitoring functions such as a received light power monitor, an LD bias monitor, and a transmission power monitor are provided.
These functions are used in the near-end measurement state, that is, in the loop-back state, for simplicity in measurement. That is, these monitor commands are transmitted in the loopback state.

However, if these monitor commands or loopback release commands are mistakenly used as loopback commands for other regenerative repeaters other than the regenerative repeater in the loopback state due to the following factors, A closed loop is formed by the back.

(I) Artificial malfunction at the transmitting terminal (ii) 装置 Equipment malfunction (iii) Distortion on the transmission line This will be described more specifically with reference to FIG.

Now, a loopback command is sent from the terminal station 22 to the regenerative repeater Rj-U to form a loop 25 with the regenerative repeater Rj-D. Suppose that various monitor commands are sent to the regenerative repeaters Rj-U, D. However, if these commands erroneously become loop commands for the regenerative repeater Ri-D due to the reasons (i) to (iii) described above,
24 are formed, and the regenerative repeaters Ri-U to Rj-U, Ri-U
A closed loop 26 consisting of D to Rj-D and loops 24 and 25 is formed.

As a result, in such a state, the regenerative repeater Ri
Since the signal from the terminal station 22 and the signal in the closed loop 26 are simultaneously input to -U, the monitoring command from the terminal station 22 is not propagated to the repeaters following the regenerative repeater Ri-U. Therefore, there is a disadvantage that the closed loop 26 cannot be released.
Incidentally, this causes the same problem even when operated from the terminal station 23.

Therefore, a technical object of the present invention is to provide an optical repeater monitoring circuit that avoids the configuration of a closed loop in view of the above-mentioned drawbacks.

[Means to solve the problem]

According to the present invention, in an optical repeater monitoring circuit having a loopback function of returning an optical signal transmitted to its own repeater to another repeater based on an external command, the command is a loopback command or a loopback release. Command identification means for identifying whether the command is a command, relay command number identification means for identifying whether the command is a command for the own repeater or a command for another repeater, and the command identification means and the repeater number identification means. A loopback means for looping back the optical signal transmitted to its own repeater to any other repeater based on the output signal; and if the command is a loopback command for any other repeater, any one of the other repeaters Closed loop avoidance means for inhibiting the loopback of the loopback means until a loopback release command of the device is received. Optical repeater monitoring circuit of symptoms is achieved.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an optical repeater including an optical repeater monitoring circuit according to one embodiment of the present invention. This is shown in the block diagram of the optical repeater including the conventional optical repeater monitoring circuit shown in FIG. 2 in which the AND gate circuits 12, 13, the inverter circuit 14, the SR F / F circuit 1
5 are added, and the same reference numerals correspond to the functions shown in FIG. Therefore, normal loopback and loopback release operations are the same as the operations in FIG.

First, in the optical repeater monitoring circuit of this embodiment, when a loopback command of another regenerator is received, the loopback command output 20 of the command identification circuit 8 is at H level, and the output 21 of the repeater number identification circuit 9 is It goes to the L level, but the newly added inverter circuit 14 causes the AND gate circuit 12
Is at H level, whereby the output of the SRF / F circuit 15 is at L level.

Therefore, when the loop-back command of the self-regenerative repeater 1-U is next received and the output of the AND gate circuit 10 goes high, the output of the AND gate circuit 13 goes low, so Not formed.

When a loopback release command of any of the regenerative repeaters is received, the output of the SRF / F circuit 15 becomes H level, and a normal loopback operation becomes possible.

As described above, in the present circuit, the loopback operation of the own repeater is not performed until the loopback release command of any of the repeaters is received after receiving the loopback command of the other repeater. Referring to FIG. 3, the loop 25
Even if the terminal 22 erroneously sends the Ri-D loopback command during the configuration, the loop 24 is not formed and the closed loop 26 cannot be formed.

That is, the present embodiment is directed to an optical repeater monitoring circuit having a loopback function of returning an optical signal transmitted to its own repeater to another repeater based on an external command, wherein the command is a loopback command or a loopback command. Command identification means 8 for identifying a release command; repeater number identification means 9 for identifying whether the command is a self-repeater or an instruction for another repeater; command identification means 8 and repeater number identification means 9 Loopback means (6, 16 to 18) for looping back the optical signal transmitted to its own repeater to one of the other repeaters based on the output signal of the other repeater; In the case of, a closed loop avoiding means for inhibiting the loopback of the loopback means until receiving a loopback release command of any other repeater. An optical repeater monitoring circuit characterized by the following.

〔The invention's effect〕

As described above, according to the present invention, the loopback of its own repeater can be prohibited until the loopback release command of any one of the repeaters is received from when the loopback command of the other repeater is received. There is an effect that a closed loop configuration can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical repeater according to an embodiment of the present invention. FIG. 2 is a block diagram of a conventional optical repeater. FIG. 3 is a diagram showing a connection between a terminal station and an optical repeater. 1 ... Regenerator, 2 ... Transmission path, 3 ... O / E converter, 4 ...
Regeneration circuit, 5 E / O converter, 6 Optical branch circuit, 7 Command demodulation circuit, 8 Command identification circuit, 9 Repeater number identification circuit, 10, 11, 12, 13 ... AND gate circuit, 14 ... Inverter circuit, 15,16 ... SR F / F circuit, 17 ... Optical shutter drive circuit, 18 ... Optical shutter, 19 ... Loop back release command output, 20 ... Loop back Command output, 21 ... Repeater identification signal output, 22, 23 ... Terminal, 24, 25 ... Loop, 26 ...
Closed loop Note: Suffix U is for uplink and D is for downlink.

Continued on the front page (72) Inventor: Shu Yamamoto 2-1-23, Nakameguro, Meguro-ku, Tokyo Inside the Research Institute of International Telegraph and Telephone Corporation (72) Inventor: Hiroharu Wakabayashi 2-1-2-3, Nakameguro, Meguro-ku, Tokyo No. International Research Institute of Telegraph and Telephone Corporation (56) References 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 loopback function for returning an optical signal transmitted to its own repeater to another repeater based on an external command, wherein the command is a loopback command or a loopback release command. Command identification means for identifying whether or not the command is an instruction for the own repeater or an instruction for another repeater; output signals of the command identification means and the repeater number identification means Loopback means for looping back the optical signal transmitted to its own repeater to any other repeater based on the above, and if the command is a loopback command for any one of the other repeaters, any one of the other repeaters A closed loop avoiding unit for inhibiting the loopback of the loopback unit until a loopback release command is received. Optical repeater monitoring circuit that.