JPH02155323A - Supervisory system for optical repeater - Google Patents

Abstract

PURPOSE:To control an average reception power of an evaluating interference optical signal and to obtain code error information by sending a prescribed signal added with a parity code to a repeater from one terminal station and sending a prescribed control signal from other terminal station. CONSTITUTION:An outgoing terminal station 11 sends an optical signal S of a code string added with a parity code such as a 24 BIP code to an incoming repeater 10a of a repeater 10. In this case, an incoming terminal station 12 sends an optical signal of a prescribed command (control signal) to an outgoing repeater 10b. A code error margin control circuit 7b controls an optical transmission circuit 4b according to the inputted prescribed to output the evaluating interference optical signal X applied with prescribed low frequency modulation to a receiver 1a of the incoming repeater 10a via an optical variable attenuation circuit 6b. An error supervisory circuit 5a detects a code error and controls the average received optical power for an interruption optical signal X.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of an optical repeater monitoring system for monitoring the margin against code errors of an optical submarine repeater.

[Conventional technology]

Conventionally, there have been the following two methods for measuring the margin against code errors of a PCM optical submarine repeater (hereinafter referred to as a repeater). One is an S/X test that measures the S/X margin of a single repeater.

The other method is to provide a monitoring identification circuit separately from the transmission identification circuit that is pre-equipped in the repeater and measure the margin against code errors.

[Problem to be solved by the invention]

However, since the former S/X test is performed on a single repeater, it is not possible to measure the S/X margin of the repeater if it is installed in a relay transmission line system. Ta.

On the other hand, in the latter method, since a monitoring identification circuit is added to the repeater, the circuit configuration of the repeater becomes complicated, and the identification sensitivity of the transmission identification circuit and the monitoring identification circuit must be matched. Therefore, it was difficult to implement this method.

[Means to solve the problem]

The optical repeater monitoring system of this invention (uplink repeater and downlink repeater K) has the following means.

(-) A control circuit that performs a predetermined control action according to a control signal sent from a terminal station, (b) An error monitoring circuit that detects code errors by parity check and outputs code error information, (c) Instructions for the control circuit. (d) an optical variable attenuation circuit that attenuates and outputs the interference optical signal according to instructions from the control circuit; (-) interference light output from this optical variable attenuation circuit; Former loopback path that superimposes the signal on the human-powered optical signal.

[Effect]

When one terminal station sends a predetermined signal with a parity code added to the uplink repeater, and the other terminal station sends a predetermined control signal to the downlink repeater, code error information is transmitted to the terminal station according to instructions from the control circuit. sent to.

〔Example〕

First, let me explain the S/X margin.

The S/X margin is one of the measures for evaluating the operating margin of a repeater, and the method for measuring the S/X margin is as follows. That is, at the input end of the repeater, 1 for a predetermined input optical signal or a pseudo-random signal (PN signal)
By superimposing a rectangular wave evaluation interference optical signal having a low frequency of about 0 MHz, code amount interference is forcibly generated at the input of the identification circuit of this repeater, thereby causing a code error. At this time, the average received light power of a predetermined input optical signal input to the repeater or the optical signal of the Sumi random signal and the total code error generated in this repeater are used for evaluation, which are superimposed to degrade the code error rate to a predetermined code error rate. The ratio of the interference optical signal to the average received light power is defined as the S/X margin, and is usually expressed in (dB) units. Further, this S/X margin is also used as a measure for evaluating characteristic deterioration of a repeater.

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

The figure is a block diagram showing a repeater in one embodiment of the present invention.

This repeater 10 includes an uplink repeater 10 & which relays a signal sent from a lower terminal station 11 to an upper υ terminal station 12, and an uplink repeater 10& which relays a signal sent from a lower terminal station 11 to an upper terminal station 12, and a signal which is sent from an upstream terminal station 12 to a downstream terminal station 11, contrary to this repeater 1Oa. and a downlink repeater 10b that relays signals.

1m, 1b are light receivers with two-power power, 2m, 2b are light receiving circuits that convert optical signals input by light receivers 1&, 1b into electrical signals, 3&, 3b are light receiving circuits '1m, 2b' are light receiving circuits that convert input optical signals into electrical signals. identification and reproducing circuit for performing identification and reproducing for the 4
Reference numerals h and 4b denote optical transmission circuits that convert electrical signals outputted from the identification and reproduction circuits 3 & 3h into optical signals and output the optical signals.

7? , 5'+5b are error monitoring circuits that count errors by parity check, and 6&, 6b attenuate the output optical signals of optical transmitting circuits 4m and 4b, and send them to optical receivers 1b and ia via optical loopback paths am and ab. This is an optical variable attenuation circuit that outputs. 7a and 7b are code error margin control circuits that control the optical transmission circuits 4m and 4b and the optical variable attenuation circuits 6m and 6b according to commands sent from the downstream terminal station 11 and the upstream terminal station 12, and this code error margin control circuit The circuits 7&, 7b are connected to each other to exchange commands and data.

Note that normally, a plurality of repeaters are provided between the downstream terminal station 11 and the upstream terminal station 12, but these are omitted in the figure and only one relay is provided.
Only one repeater 10 is shown.

Next, the operation when determining the S/X margin of the repeater 10 in the above configuration will be described.

First, the downlink terminal station 11 sends an optical signal S of a code string to which a parity code is added, such as a 24 BIP code, to the uplink repeater 10& of the repeater 10. The transmitted optical signal is sent to receiver 1
A and the receiving circuit 2a convert the signal into an electrical signal, which is output to the identification/reproduction circuit 3a, where the error monitoring circuit 5a performs a parity check to perform an error count.

At this time, the upstream station 2 sends an optical signal of a predetermined command (control signal) to the downstream repeater 10b. The transmitted optical signal of the predetermined command is converted into an electrical signal by the optical receiver 1b and the receiving circuit 2b, and is input to the code error margin control circuit 7b via the identification and reproducing circuit 3b. The code error margin control circuit γb controls the optical transmitter circuit 4b according to a predetermined command input, thereby generating an evaluation interference optical signal (hereinafter referred to as an interference optical signal) X subjected to a predetermined low frequency modulation.
is output to the light receiver 1a of the uplink repeater 10a via the optical variable attenuation circuit 6b. At this time, the code error correction/control circuit 7b can control the modulation level of the optical transmitter circuit 4b and the attenuation amount of the optical variable attenuation circuit 6b in accordance with the above-mentioned predetermined command. It is possible to control the average received light power of the interference optical signal X output to 1&.

As a result of the above, in the light receiver 11L, the interference optical signal X sent out from the optical variable attenuation circuit 6b is superimposed on the optical signal S sent out from the downlink terminal station 11.

Here, the error monitoring circuit 5a detects a code error and also controls the average received light power of the interference optical signal X as described above. Then, when the code error detected by the error monitoring circuit 5a has deteriorated to a predetermined code error rate, the average received power of the optical signal S and the interference optical signal The S/X margin of the repeater 1Oa can be determined.

Note that the average received light power of the optical signal S at the optical receiver 1a is obtained by subtracting the transmission loss of the transmission line from the output level of the downlink terminal station 11. Additionally, the error monitoring circuit 5a
Information on the code error detected in is transmitted to the downstream terminal station 11 and the upstream terminal station 12 by the action of the code error margin control circuits 7& and 7b.

In addition, in the above operation, the S/X margin of the repeater 1Oa (above) was determined, but it goes without saying that the S/X margin of the downlink repeater 10b can be determined using almost the same procedure. do not have.

〔Effect of the invention〕

As explained above, according to the present invention, a predetermined signal with a parity code added is sent from one terminal station to the repeater,
By sending a predetermined control signal from the other terminal station, it is possible to control the average received power of the interference optical signal for evaluation and obtain code error information, so it is not necessary to add an identification circuit for monitoring as in the past. It is possible to measure the S/X margin of a repeater installed in a relay transmission line system.

- Furthermore, by measuring the S/X margin, it becomes possible to monitor the aging deterioration of repeaters installed in the relay transmission line system.

[Brief explanation of the drawing]

The figure is a block diagram of a repeater in one embodiment of the present invention. 4a+4b... Optical transmission circuit, 5a, 5b... Error monitoring circuit, 5m, 5b... Optical variable attenuation circuit, 7
a, γb... Sign error margin control circuit, 8 &, 8
b... Optical loopback path, 1o... Repeater, 1
0a... Uplink repeater, 10b... Downlink repeater,
11...downstream terminal station, 12.Φ...upstream terminal station.

Claims (1)

[Claims] In a relay transmission line in which optical fibers and repeaters are alternately connected between terminal stations, the S/X margin of the uplink repeater and the downlink repeater that constitute the repeater An optical repeater monitoring system that seeks to detect code errors, comprising: a control circuit that performs a predetermined control action on the uplink repeater and the downlink repeater according to a control signal sent from a terminal station; and a parity check to detect code errors. an error monitoring circuit that detects and outputs code error information; an optical transmission circuit that outputs a predetermined interference optical signal according to instructions from the control circuit; and an optical transmission circuit that attenuates the interference optical signal according to instructions from the control circuit. A variable optical attenuation circuit is provided to output the signal, and an optical loopback path is provided to superimpose the interference optical signal output from the variable optical attenuation circuit on the input optical signal, and a parity code is transmitted from one terminal station to an uplink repeater. the predetermined signal added thereto, the predetermined control signal is sent from the other terminal station to the downlink repeater, and the code error information is transmitted to the terminal station according to instructions from the control circuit. Features optical repeater monitoring method.