JPS6212217A - Optical communication system - Google Patents

Abstract

PURPOSE:To switch automatically a line having an LD deterioration fault to a standby line by switching the line having LD deterioration fault to the standby line, sending fault detecting information to an opposite station and allowing the opposite station to receive and detect the fault detection information. CONSTITUTION:An optical transmission section applies an automatic output control (APC) to control a drive current thereby keeping the optical output of the LD constant, and when the drive current of the LD is monitored and the drive current exceeds a threshold value, it is discriminated to be deterioration in the LD. The optical output signal is formed into, e.g., consecutive '1' data by the detection of deterioration and sent to the opposite station, and the own station switches the information of an active line into the standby line. On the other hand, the optical reception section of the opposite station detects the consecutive '1' data pattern to switch the active line to the standby line. Thus, the active line relating to LD deterioration is switched automatically to the standby line.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides an optical communication system in which, when a semiconductor laser as a transmission light source deteriorates, a transmission system including the semiconductor laser is switched to a backup transmission system. It is related to the method.

[Background of the invention]

Optical ■χ transmission using optical fiber cables is being put into practical use in various fields because it has short relay distance and transmission capacity, and is easy to maintain. In this optical PCM transmission system, a semiconductor laser (hereinafter referred to as LD) is often used as a light source, but when using J, the reliability of the part is not as good as that of other parts, and therefore the transmission system In order to improve reliability, many systems are equipped with backup lines. Up to now, the actual situation has been to use an optical fiber cable with an intervening pair of metallic wires as a transmission line, and to switch to a protection line by transmitting fault information via the metallic wire. be. Normal transmission is ensured by switching the faulty line to the protection line, but since the fault information is transmitted by the intervening pair, it is easy to switch to the protection line. There is a problem that there is no. Publicly known documents regarding the transmission of fault information using intervening pairs include, for example, the paper "Design and Characteristics of rF-400M Supervisory Control System" (Electric Corporation, Research and Practical Application Report Vol. 32, No. 3 (19
83), P609-620).

[Purpose of the invention]

An object of the present invention is to provide an optical communication system that can easily and automatically switch to a protection line without using an intervening pair such as a metallic line when a deterioration failure occurs in an LD.

[Summary of the invention]

For this purpose, the present invention provides that when it is detected that an LD deterioration failure has occurred in any of the plurality of working lines, the station switches the line related to the LD deterioration failure to a protection line, and While the fault detection information is transmitted to the station, the other station receives and detects the fault detection information, thereby switching the line related to the occurrence of the LD deterioration fault to a protection line. When each line consists of an uplink transmission system 2 and a downlink transmission system, the occurrence of a W degradation failure in one of the transmission systems can be transmitted to the other station via the other transmission system, and the other station will notify you of this. The line is switched to a protection line by detecting this.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to the accompanying drawings.

First, before explaining the present invention in detail, the background of the invention will be briefly explained as follows.

That is, when ] is used as a transmission light source, the reliability of J is more than an order of magnitude worse than other parts, and therefore, the majority of line failures are caused by this LDK. The present invention focuses on failures caused by this LD in an optical communication system having a working line and a protection line, and automatically switches the degraded working line to a protection line simply and easily based on the detection of J deterioration. This is what we are trying to do.

By the way, the method for detecting W deterioration is based on drive current. Generally, automatic output control (APC) is performed in the optical transmitter to control the drive current to keep the optical output of J constant, but the drive current of W is monitored and if the drive current exceeds a certain threshold, It is determined that the LD has deteriorated.

By detecting this deterioration, the optical output signal is converted into, for example, continuous "1" data and transmitted to the other station, and at the same time, the local station switches the information on the working line to the protection line. On the other hand, in the other station, the optical receiver detects the continuous 111 data pattern and switches the working line to the protection line. This makes it possible to automatically switch the working line related to D deterioration to the protection line.

Note that the deterioration of the LD may be determined as LD deterioration when its optical output level becomes smaller than a certain threshold value, and a similar effect can be expected.

Now, the present invention will be specifically explained. The figure shows the system configuration of an example of an optical communication system according to the present invention. In this example, the system accommodates two active lines and one standby line between stations A and B, respectively, with transmission lines 5,
It is assumed that transmission line 6 is allocated for active use, and transmission line 7 is allocated for backup. Transmission line 5 is down transmission line 5I
and an upstream transmission line 52, but this situation is the same for the other transmission lines 6.7. Also,
Working line A1. For A2, optical transmitter/receiver sections 2.2', 3
．． 5', optical transmitter/receivers 4, 4' are provided for the protection line, but they all have the same configuration, and only the optical transmitter/receivers 2, 2' are shown in detail in the figure. Optical transmitter/receiver 2
(2') is selector 8 (8'), optical transmitter circuit 9 (9')
, LD deterioration detection circuit 10 (10'), optical receiving circuit 11 (
11') and continuous "1" data detection circuit 12 (12')
).

Now, assuming that the optical transmission line 9 of the working line/161 has deteriorated, the deterioration is caused by the W drive current exceeding a threshold (for example, t3 times the normal state), and a certain t. This is detected by the deterioration detection circuit 10 due to the decrease in the output level. Based on this deterioration detection, the selector 8 transmits continuous 11" data to the station B via the optical transmission circuit 9 and the down transmission line 51. At the same time, the station A controls the protection line switching unit 1 based on the deterioration detection. By doing so, the working line/I61 related to LD deterioration is switched to the protection line.On the other hand, at station B, continuous 111 data is transferred to the optical receiving circuit 11'.
Based on this detection, the protection line switching section 1' switches the working line 1 to the protection line. Switching operation is performed by other optical transmitter/receiver 2'
.

The same applies when the LD in 6.3' deteriorates, and the working line related to the deterioration is automatically switched to the protection line.

〔Effect of the invention〕

As explained above, in the case of the present invention, when W deteriorates, it can be easily and easily done without requiring any intervening pair such as metallic wire.
This has the advantage that a working line related to LD deterioration can be automatically switched to a protection line.

[Brief explanation of drawings]

The figure is a diagram showing in detail the main parts of an example of the configuration of an optical communication system according to the present invention. 1.1'...protection line switching section, 2, 2', 5, 5', 4, 4'...optical transmitting/receiving section, 5-7...transmission line, 8, 8'...selector , 9.9'... optical transmitter circuit, 10, 10'...
- LD deterioration detection circuit, 11.11'... optical receiving circuit, 12, 12'... continuous 111 data detection circuit.

Claims (1)

[Claims] Having one or more working lines and protection lines between two stations,
This is an optical communication method in an optical communication system in which each of the lines includes two optical fiber transmission lines whose transmission directions are opposite to each other. In this case, the station switches the line related to the semiconductor laser deterioration to a backup line, and transmits failure detection information to the other station via the transmission optical fiber transmission line of the line related to the semiconductor laser deterioration, An optical communication system characterized in that the other station detects the failure detection information to switch a line related to semiconductor laser deterioration to a protection line. 2. The optical communication system according to claim 1, wherein deterioration of the semiconductor laser is detected from the magnitude of the semiconductor laser drive current. 3. The optical communication system according to claim 1, wherein deterioration of the semiconductor laser is detected from the magnitude of the optical output level of the semiconductor laser.