JPH02223237A - Optical submarine repeater - Google Patents

Abstract

PURPOSE:To eliminate the need for sending a command signal, etc., and to reduce the costs of a repeater and a terminal station by sending a monitoring signal with frequency different at every repeater from each repeater superposingly to a PCM signal. CONSTITUTION:An optical transmission signal transmitted on an optical fiber 2 is composed of a fast PCM signal offered to a service and a low frequency monitoring signal with frequency different at every repeater issued from another repeater, and light reception circuit 5, in receiving the optical transmission signal, converts it to an electrical transmission signal, then, outputs it to a filter 6. The filter 6 separates the monitoring signal of low frequency band area from the transmission signal outputted from the circuit 5, and outputs it to an amplifier 10. A light emitting element driving circuit 13 drives a light emitting element 14 after superposing a monitoring signal group from a coupler 11 on the PCM signal outputted from an identification circuit 9, and the light emitting element 14 sends the optical transmission signal to the optical fiber 2. Thereby, it is possible to eliminate the command signal, which solves the problem of interference on the transmission signal, and to reduce the costs of the repeater and the terminal station, and furthermore, to eliminate a skilled operator to the monitoring control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical submarine repeater for an optical submarine cable system that can be monitored in-service.

[Conventional technology]

Conventionally, as submarine repeaters that can be monitored in-service, there are FDM submarine coaxial cable systems with a built-in monitoring frequency oscillator and loop gain type repeaters that increase the gain at the assigned frequency, but PCM optical submarine cables In some systems, the bit error rate is measured individually at each relay using a command signal from the terminal station, and the bias current of the laser diode is measured by replacing the frame format (for example, JOURNAL
0FLIGHTWAVE TECHNOLOGY, V
OL, LT-2, NO, 6° DEC, 1984).

[Problem to be solved by the invention]

However, in optical submarine cable systems using such optical submarine repeaters, it is necessary to send command signals for monitoring from the terminal station, and the command signals are multiplexed at the same speed as the transmission signal, so interference may occur. This may adversely affect the transmission signal.

Furthermore, the monitoring circuit within the repeater is complex and large-scale, resulting in high cost. Furthermore, even in the terminal stations, the monitoring and control equipment becomes large-scale and costly, and furthermore, a skilled operator is required to control the equipment.

An object of the present invention is to provide an optical system that eliminates the need for command signals to solve the problem of interference with transmission signals, reduces the cost of repeaters and terminal stations, and eliminates the need for skilled operators for supervisory control at terminal stations. Our goal is to provide submarine repeaters.

[Means to solve the problem]

The present invention includes a light receiving circuit that converts an optical transmission signal from an optical fiber constituting a submarine cable into an electrical transmission signal and outputs it, and a first light receiving circuit that equalizes and amplifies the transmission signal from the light receiving circuit.
an amplifier, a timing circuit for extracting a clock component from the transmission signal from the amplifier, and a frequency of the clock component extracted by the timing circuit to identify and reproduce a PCM signal from the transmission signal output from the amplifier. An output identification circuit and the PC from this identification circuit.
In an optical submarine repeater equipped with a regenerative amplifier having a light emitting element drive circuit that drives a light emitting element based on the M signal and performs optical modulation, a monitoring oscillator that outputs a monitoring signal of a frequency assigned to the regenerative amplifier; , separating a line transmission speed transmission signal from the transmission signal output by the light receiving circuit and outputting it to the first amplifier; and separating and outputting a low frequency band monitoring signal from the transmission signal output by the light receiving circuit. a second amplifier that amplifies and outputs the monitoring signal outputted by the filter; and a second amplifier that superimposes the monitoring signal from the monitoring oscillator on the monitoring signal from the second amplifier to generate the light emitting element. a coupler connected to a drive circuit, the light emitting element drive circuit comprising:
It is characterized in that the signal from this coupler is superimposed on the PCM signal to drive the light emitting element.

〔Example〕

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

FIG. 1 is a block diagram showing an embodiment of an optical submarine repeater according to the present invention. This optical submarine repeater 3 includes two regenerative amplifiers 4 for uplink and downlink, each of which has a light receiving circuit 5 that converts an optical transmission signal from an optical fiber 2 constituting a submarine cable 1 into an electrical transmission signal and outputs it. A first amplifier 7 receives the transmission signal from the light receiving circuit from a frequency separation filter 6 (described later), equalizes and amplifies it, a timing circuit 8 extracts a clock component from the transmission signal from this amplifier, and a timing circuit 8 which extracts a clock component from the transmission signal from this amplifier. An identification circuit 9 identifies and reproduces a PCM signal from the transmission signal output by the amplifier 7 based on the frequency of the clock component extracted by the timing circuit, and drives the light emitting element 14 based on the PCM signal from this identification circuit.
A light emitting element drive circuit 13 that performs optical modulation is provided.

Each regenerative amplifier 4 further includes a monitoring oscillator 12 that outputs a monitoring signal of a frequency assigned to each regenerative amplifier as a component related to repeater monitoring, and a monitoring oscillator 12 that outputs a monitoring signal of a frequency assigned to each regenerative amplifier, and a monitoring oscillator 12 that outputs a monitoring signal of a frequency assigned to each regenerative amplifier, and a monitoring oscillator 12 that determines the line transmission speed from the transmission signal outputted by the light receiving circuit 5. A frequency separation filter 6 separates the transmission signal and outputs it to the amplifier 7, and also separates and outputs a monitoring signal in a low frequency band from the transmission signal outputted by the light receiving circuit 5, and a frequency separation filter 6 which amplifies the monitoring signal outputted by this filter. and a coupler 11 that superimposes the monitoring signal from the monitoring oscillator 12 on the monitoring signal from the second amplifier and outputs the superimposed signal to the light emitting element drive circuit 13.

Next, the operation will be explained. The optical transmission signal transmitted through the optical fiber μ2 consists of a high-speed PCM signal provided for service and a low-frequency monitoring signal that is transmitted from other repeaters and has a different frequency for each repeater, and the light receiving circuit 5 When this optical transmission signal is received, it is converted into an electrical transmission signal and output to the filter 6. The filter 6 separates the line transmission speed transmission signal from the transmission signal output by the light receiving circuit 5 and outputs it to the amplifier 7 , and also separates the low frequency band monitoring signal from the transmission signal output from the light receiving circuit 5 and outputs it to the amplifier 10 . Output to.

Amplifier 7 equalizes and amplifies the transmission signal from filter 6 and outputs it to identification circuit 9 and timing circuit 8. The timing circuit 8 extracts a clock component from the transmission signal from the amplifier 7, and the identification circuit 9 identifies and reproduces the PCM signal from the transmission signal output from the amplifier 4 based on the frequency of the clock component extracted by the timing circuit, and emits light. Element drive circuit 1
Output to 3.

On the other hand, the amplifier 10 amplifies the monitoring signal from the filter 6 in order to compensate for the optical line loss in the repeater section, and the coupler 11
superimposes the monitoring signal from the monitoring oscillator 12 on this amplified monitoring signal and outputs it to the light emitting element drive circuit 13. The light emitting element driving circuit 13 then superimposes the group of monitoring signals from the coupler 1 on the PCM signal output by the identification circuit 9 to drive the light emitting element 14, and the light emitting element 14 then transmits the optical transmission signal to the optical fiber. Send to 2.

In this way, in the optical submarine cable system using the optical submarine repeater of the present invention, each repeater transmits a monitoring signal with a different frequency for each repeater, superimposed on the PCM signal. In this state, each repeater can be monitored by arranging these monitoring signals on the frequency axis. Since the monitoring signal is superimposed on the PCM signal in an analog manner at the repeater, the influence of the monitoring signal on the PCM signal, which is the main transmission signal, is extremely small. In addition, the circuit configuration related to repeater monitoring is simple, and the monitoring equipment on the terminal side is also simple.
Since there is no need to send out command signals, the system is small-scale, and the cost of repeaters and terminal stations can be reduced. Furthermore, since the operations to be performed on the terminal side are simplified, an operator skilled in monitoring and control is not required.

〔Effect of the invention〕

As explained above, the present invention includes a light receiving circuit that converts an optical transmission signal from an optical fiber constituting a submarine cable into an electrical transmission signal and outputs it, and a first light receiving circuit that equalizes and amplifies the transmission signal from this light receiving circuit. An amplifier, a timing circuit that extracts a clock component from the transmission signal from this amplifier, and the frequency of the clock component extracted by this timing circuit,
A regenerative amplifier includes an identification circuit that identifies and reproduces a PCM signal from a transmission signal output from the amplifier and outputs the same, and a light emitting element drive circuit that drives a light emitting element and performs optical modulation based on the PCM signal from the identification circuit. In the optical submarine repeater equipped with the system, a monitoring oscillator outputs a monitoring signal at a frequency assigned to the regenerative amplifier, and a transmission signal at a line transmission speed is separated from the transmission signal output by the light receiving circuit and output to the first amplifier. , a filter that separates and outputs a monitoring signal in a low frequency band from a transmission signal output by the light receiving circuit, a second amplifier that amplifies and outputs the monitoring signal output from this filter, and a second amplifier that amplifies and outputs the monitoring signal output from the filter. and a coupler that superimposes the monitoring signal from the monitoring oscillator on the monitoring signal from the monitoring oscillator and outputs it to the light emitting element drive circuit, and the light emitting element drive circuit superimposes the signal from the coupler on the PCM signal to drive the light emitting element. do.

Therefore, in the optical submarine cable system using the optical submarine repeater of the present invention, each repeater sends out a monitoring signal with a different frequency superimposed on the PCM signal, so that the terminal station is in an in-service state. Each repeater can be monitored by arranging these monitoring signals on the frequency axis. Since the monitoring signal is superimposed on the PCM signal in an analog manner at the repeater, the influence of the monitoring signal on the PCM signal, which is the main transmission signal, is extremely small. In addition, the circuit configuration related to repeater monitoring is simple, and the monitoring device on the terminal station side is also small-scale since there is no need to send out command signals, reducing the cost of repeaters and terminal stations. Can be reduced. Furthermore, since the operations to be performed on the terminal side are simplified, an operator skilled in monitoring and control is not required. Furthermore, since the device is small in size and easy to operate, maintenance is also easy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an optical submarine repeater according to the present invention. 1... Submarine cable 2... Optical fiber 3... Optical submarine repeater 4... Regenerative amplifier 5... Light receiving circuit 6... Frequency separation filter 7... Equalization amplifier 8... Timing circuit 9...Identification circuit 10...Amplifier 11...Coupler 12...Monitoring oscillator 13...Light emitting element drive circuit 14...Light emitting element

Claims (1)

[Claims] (1) A light receiving circuit that converts an optical transmission signal from an optical fiber constituting a submarine cable into an electrical transmission signal and outputs it, a first amplifier that equalizes and amplifies the transmission signal from this light receiving circuit, and this amplifier. a timing circuit that extracts a clock component from the transmission signal from the amplifier; and an identification circuit that identifies and reproduces a PCM signal from the transmission signal output from the amplifier based on the frequency of the clock component extracted by the timing circuit. In an optical submarine repeater equipped with a regenerative amplifier having a light emitting element drive circuit that drives a light emitting element and performs optical modulation based on the PCM signal from the identification circuit, a monitoring signal of a frequency assigned to the regenerative amplifier is provided. a monitoring oscillator that outputs a transmission signal at a line transmission speed from the transmission signal output by the light receiving circuit, and outputting the separated transmission signal to the first amplifier, and monitoring a low frequency band from the transmission signal output by the light receiving circuit. a filter that separates and outputs signals; a second amplifier that amplifies and outputs the monitoring signal output by the filter; a coupler that superimposes the signal and outputs it to the light emitting element drive circuit, the light emitting element drive circuit driving the light emitting element by superimposing the signal from the coupler on the PCM signal. submarine repeater.