JP2504166B2 - Optical submarine repeater - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical submarine repeater of an optical submarine cable system that can be monitored in service.

[Prior Art] Conventionally, as an undersea repeater that can be monitored in service, there are an FDM submarine coaxial cable system with a built-in monitoring frequency oscillator and a loop gain type that increases the gain at an assigned frequency. In the PCM optical submarine cable system, there is a method in which the code error rate is individually measured in each relay by 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 OF LIGHTWA
VE TECHNOLOGY, Vol.LT-2, NO.6, DEC. 1984).

[Problems to be Solved by the Invention]

However, in an optical submarine cable system using such an optical submarine repeater, it is necessary to send a command signal for monitoring from the terminal station, and since the command signal is multiplexed at the same speed as the transmission signal, there is no interference. May adversely affect the transmission signal. Further, the monitoring circuit in the repeater is complicated and large in scale, and the cost is high. Also, in the terminal station, the monitoring control device becomes large in scale and the cost becomes high, and a skilled operator is required to control the device.

An object of the present invention is to solve the problem of interference with transmission signals by eliminating the need for command signals, reduce the cost of repeaters and terminal stations, and eliminate the need for operators who are skilled in supervisory control at terminal stations. It is to provide a submarine repeater.

[Means for solving the problem]

In order to achieve the above object, the present invention inputs an optical transmission signal consisting of a high-speed PCM signal provided for service and a low-frequency monitoring signal having a different frequency for each repeater transmitted from another repeater. A light receiving circuit for converting into a transmission signal and outputting it to the frequency separation filter, and a transmission signal output from the light receiving circuit after separating the transmission signal of the line transmission speed from the transmission signal output from the light receiving circuit and outputting it to the first amplifier. Separation filter for separating the monitoring signal in the low frequency band from the output to the second amplifier, and a first amplifier for equalizing and amplifying the transmission signal output from the frequency separation filter and outputting to the identification circuit and the timing circuit A timing circuit for inputting the transmission signal output from the first amplifier and outputting a clock component to the identification circuit; and a frequency component of the clock component output from the timing circuit. An identification circuit that identifies and reproduces a PCM signal from the transmission signal output from the first amplifier and outputs it to the light emitting element drive circuit, and a second amplifier that amplifies the monitoring signal output from the frequency separation filter and outputs it to the coupler. , Superimpose the supervisory signal from the supervisory oscillator on the amplified supervisory signal and output it to the light emitting element drive circuit, and superimpose the supervisory signal group output from the combiner on the PCM signal output from the identification circuit. A light emitting element drive circuit for outputting to a light emitting element and a light emitting element for receiving a signal output from the light emitting element drive circuit and outputting an optical transmission signal to an optical fiber are provided.

[Embodiment] Next, an embodiment 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. The optical submarine repeater 3 includes two regenerative amplifiers 4 for upstream and downstream, and a light receiving circuit 5 for converting an optical transmission signal from an optical fiber 2 constituting a submarine cable 1 into an electrical transmission signal and outputting the electrical transmission signal. A first amplifier 7 for equalizing and amplifying a transmission signal from the light receiving circuit from a frequency separation filter 6 described later; a timing circuit 8 for extracting a clock component from the transmission signal from the amplifier; and a timing circuit for this timing circuit. The discrimination circuit 9 discriminates and reproduces a PCM signal from the transmission signal output from the amplifier 7 according to the frequency of the clock component extracted by the amplifier 7, and the light emitting element 14 is driven based on the PCM signal from the discrimination circuit to perform optical modulation. And a light emitting element drive circuit 13 for performing the above.

Each regenerative amplifier 4 further includes, as components related to the monitoring of the repeater, a monitoring oscillator 12 that outputs a monitoring signal of a frequency assigned to each regenerative amplifier, and a transmission signal output from the light receiving circuit 5 to change the line transmission speed. The transmission signal is separated and output to the amplifier 7, and the frequency separation filter 6 that separates and outputs the monitoring signal in the low frequency band from the transmission signal output by the light receiving circuit 5 and the monitoring signal output by this filter are amplified. And a coupler 11 for superimposing the monitor signal from the monitor oscillator 12 on the monitor signal from the second amplifier and outputting the superposed signal to the light emitting element drive circuit 13.

Next, the operation will be described. The optical transmission signal transmitted through the optical fiber 2 is composed of a high-speed PCM signal provided for service and a low-frequency monitoring signal having a different frequency for each repeater transmitted from another repeater. When the transmission signal is received, it is converted into an electric transmission signal and output to the filter 6. The filter 6 separates the transmission signal of the line transmission speed from the transmission signal output from the light receiving circuit 5 and outputs it to the amplifier 7, and separates the monitoring signal of the low frequency band from the transmission signal output from the light receiving circuit 5 to output the amplifier 10. Output to.

The amplifier 7 equalizes and amplifies the transmission signal from the filter 6 and outputs it to the identification circuit 9 and the timing circuit 8. The timing circuit 8 extracts the 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 by the amplifier 4 according to the frequency of the clock component extracted by the timing circuit, and emits light. Element drive circuit 13
Output to.

On the other hand, the amplifier 10 amplifies the supervisory signal from the filter 6 in order to compensate the optical line loss in the repeater section, and the coupler 11
Superimposes the supervisory signal from the supervisory oscillator 12 on the amplified supervisory signal and outputs it to the light emitting element drive circuit 13. Then, the light emitting element drive circuit 13 superimposes the supervisory signal group from the coupler 11 on the PCM signal output from the identification circuit 9 and
4 is driven, and the light emitting element 14 consequently sends out an optical transmission signal to the optical fiber 2.

As described above, in the optical submarine cable system using the optical submarine repeater of the present invention, each repeater sends a supervisory signal having a different frequency for each repeater, which is superposed on the PCM signal and sent out. In this state, these monitoring signals can be arranged on the frequency axis to monitor each repeater. Since the supervisory signal is superimposed on the PCM signal in an analog manner in the repeater, the influence of the supervisory signal on the PCM signal which is the main transmission signal is extremely small. In addition, the circuit configuration related to the monitoring of the repeater is simple, and the monitoring device on the terminal station side does not need to send a command signal, etc. It can be reduced. Further, since the operation to be performed on the terminal side becomes simple, an operator who is skilled in monitoring and control is not required.

〔The invention's effect〕

As described above, according to the present invention, a light receiving circuit that converts an optical transmission signal from an optical fiber that constitutes a submarine cable into an electrical transmission signal and outputs the electric transmission signal, and a first signal that equalizes and amplifies the transmission signal from the light receiving circuit. An amplifier, a timing circuit that extracts a clock component from the transmission signal from this amplifier, and an identification circuit that identifies and reproduces a PCM signal from the transmission signal output by the amplifier according to the frequency of the clock component extracted by this timing circuit, and In an optical submarine repeater equipped with a regenerative amplifier that drives a light emitting element based on the PCM signal from this identification circuit and performs light modulation, a monitoring signal of the frequency assigned to the regenerative amplifier is displayed. The supervisory oscillator for output and the transmission signal at the line transmission speed are separated from the transmission signal output by the light receiving circuit and output to the first amplifier. Filter for separating and outputting the monitoring signal in the low frequency band from the transmission signal to be transmitted, a second amplifier for amplifying and outputting the monitoring signal output by this filter, and a monitoring oscillator for the monitoring signal from the second amplifier And a combiner for superimposing the monitoring signal from the output to the light emitting element drive circuit, and the light emitting element drive circuit superimposes the signal from the combiner on the PCM signal to drive the light emitting element.

Therefore, in the optical submarine cable system using the optical submarine repeater of the present invention, a monitoring signal of a different frequency for each repeater is transmitted by being superimposed on the PCM signal at each repeater. Then, these monitoring signals can be arranged on the frequency axis to monitor each repeater. Since the supervisory signal is superimposed on the PCM signal in an analog manner in the repeater, the influence of the supervisory signal on the PCM signal which is the main transmission signal is extremely small. In addition, the circuit configuration related to the monitoring of the repeater is simple, and the monitoring device on the terminal station side does not need to send a command signal, etc. It can be reduced. further,
Since the operation to be performed on the terminal side becomes simple, an operator who is skilled in monitoring and control is unnecessary. Further, since the scale of the device is small and the operation is easy, maintenance is easy.

[Brief description of drawings]

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 ... Regeneration amplifier 5 ... Reception 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

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04L 25/02 301

Claims (1)

(57) [Claims] 1. A high-speed PCM signal provided for service and an optical transmission signal composed of a low-frequency supervisory signal having a different frequency for each repeater transmitted from another repeater are input, converted into an electric transmission signal, and frequency-converted. A light receiving circuit for outputting to the separation filter, and a transmission signal of line transmission speed separated from the transmission signal output from the light receiving circuit, output to the first amplifier, and a monitoring signal in a low frequency band from the transmission signal output from the light receiving circuit. A frequency separation filter that separates and outputs to a second amplifier, and a first amplifier that equalizes and amplifies the transmission signal output from the frequency separation filter and outputs to the identification circuit and the timing circuit.
A timing circuit for inputting the transmission signal output from the first amplifier and outputting a clock component to the identification circuit, and a first circuit according to the frequency of the clock component output from the timing circuit
Discriminating and reproducing the PCM signal from the transmission signal outputted from the amplifier of the above and outputting it to the light emitting element drive circuit, the second amplifier for amplifying the supervisory signal outputted from the frequency separation filter and outputting it to the coupler, A supervisor that superimposes the supervisory signal from the supervisory oscillator on the supervisory signal generated and outputs it to the light emitting element drive circuit, and a supervisory signal group output from the combiner is superimposed on the PCM signal output from the identification circuit. An optical submarine repeater comprising: a light emitting element driving circuit for outputting to the optical fiber; and a light emitting element for receiving a signal output from the light emitting element driving circuit and outputting an optical transmission signal to an optical fiber.