JPH01218230A - Repeater supervising system - Google Patents

Abstract

PURPOSE:To always supervise a line in an in-service condition by equipping an oscillator and a phase modulator at respective repeaters and equipping a phase demodulator and a supervising circuit at a terminal station. CONSTITUTION:An oscillator 14 generates the signal of the low frequency of the inherent frequency of a repeater. A phase modulator 15 phase-modulates a digital signal reproduced by an identifier 13, a driving circuit 16 is driven and a light signal is sent from an electric/optical(E/O) converter 17. On the other hand, at the terminal station, an O/E converter 21 converts to an electric signal. A phase demodulator 26 phase-demodulates a clock signal reproduced by a clock reproducing circuit 25 and thus, the included phase modulation frequency component is extracted. The signal is added to filters 271-27n having respectively different passing frequencies and separated, detected respectively with supervising circuits 281-28n, and the presence and absence of the component signal can be supervised.

Description

[Detailed Description of the Invention] [Summary] Regarding a repeater monitoring method for a line including a large number of repeaters, □ Does not require a signal transmission means separate from the main signal, and does not require control from a terminal station. The purpose of this system is to provide a repeater monitoring method that can constantly monitor lines in service and quickly locate fault points. In a digital communication system that reproduces and relays a Each repeater is equipped with a demodulator that demodulates the oscillation frequency superimposed on the main signal, and a related circuit that monitors the demodulated frequency is provided at the terminal station. Configure by monitoring frequencies.

[Industrial application field]

The present invention relates to a repeater monitoring method for a line including a large number of repeaters.

In optical relay systems, particularly in long-distance submarine relay systems, it is effective to monitor the operating status of repeaters in order to locate the point of failure when a failure occurs.

The repeater monitoring method that monitors the operation of such repeaters is
It does not require a signal transmission means separate from the main signal, and there is no need for control from the terminal station, and it is possible to constantly monitor the line in service and quickly locate fault points. Certain things are required.

[Conventional technology]

Conventionally, the method for constantly monitoring optical digital repeaters is to transmit a low-frequency signal specific to each repeater from each repeater using a dedicated monitoring line or power supply line, and monitor this at the terminal station. By including a monitoring bit in the main signal (digital signal), or by superimposing a monitoring signal on the amplitude and phase of the main signal to control the repeater in-service, a signal indicating its status is sent from the intermediate device. A method is used to respond to

[Problem to be solved by the invention]

However, the method of performing line monitoring using a dedicated monitoring line requires a dedicated line. Further, in the method of transmitting the monitoring signal using a dedicated monitoring line or a power supply line, there is a problem that if the line is long, the loss of the monitoring signal increases, making it difficult to implement.

In addition, in a method in which a monitoring signal is superimposed on the amplitude and phase of the main signal to control the repeater and respond to the status, the terminal station controls the repeater and then the repeater responds to the terminal station. Only the monitoring method can be used, and it takes time to detect failure conditions, so it is not possible to respond immediately in the event of a failure. Furthermore, such a system naturally has the problem that the circuit configuration inside the repeater becomes complicated.

The present invention aims to solve the problems of the prior art as described above, and is capable of transmitting signals in an in-service state without requiring a signal transmission means separate from the main signal, and without requiring control from the terminal station. In addition to being able to constantly monitor the line,
The purpose of this invention is to provide a repeater monitoring method that can quickly locate failure points.

[Means to solve the problem]

As shown in the principle block diagram in FIG. In addition to the repeater, the terminal station is equipped with a phase demodulator 3 and a monitoring circuit 4, and the line is monitored by monitoring the oscillation frequency of each relay station at the terminal station.

The oscillator 1 generates a signal with a unique oscillation frequency corresponding to each repeater.

The phase modulator 2 phase-modulates the main signal reproduced in the repeater using the oscillation frequency of the oscillator 1.

The phase demodulator 3 demodulates the received main signal and extracts the superimposed oscillation frequency.

The monitoring circuit 4 monitors the oscillation frequency of each extracted relay station.

[For production]

In optical digital communication systems, a large number of repeaters are installed between terminal stations, and each repeater sequentially regenerates the main signal received by the receiving circuit and sends it out to the transmission path via the transmitting circuit. A circuit receives this signal and obtains an output.

In this case, each repeater is provided with an oscillator to generate a signal with a unique oscillation frequency corresponding to each repeater. This signal is applied to a phase modulator to phase modulate the main signal regenerated at the repeater.

Therefore, the main signal of the line is sequentially phase modulated by each oscillation frequency in each repeater inserted into the line, transmitted, and received by the terminal equipment.

In the terminal equipment, a demodulator phase-demodulates the main signal, extracts the unique oscillation frequency of each superimposed repeater, and separates each oscillation frequency using a filter having a pass frequency corresponding to each frequency. , each monitoring circuit detects the presence or absence of each frequency component.

Therefore, if a failure occurs in the repeater inserted into the line,
The oscillation frequency signal from the repeater before the fault point is not detected, and the repeaters after the fault point send random noise signals from the light receiving elements to the terminal station. The oscillation frequency is detected at the terminal station. This makes it possible to monitor each repeater while it is in service.

〔Example〕

FIG. 2 shows an embodiment of the present invention, (a
1 indicates the configuration of the repeater, and the crest) indicates the configuration of the terminal equipment. ' In the repeater, the digital optical signal from the fiber optic cable line is applied to an optical/electrical (0/E) converter it to be converted into an electrical signal. After this signal is amplified as required in an amplifier 12, it is applied to a discriminator 13 where it is discriminated by a constant darkness value to reproduce a digital signal.

On the other hand, one oscillator 14 has a frequency ft specific to that repeater.
Generates a low frequency signal. This signal is transmitted to the phase modulator 15
The phase modulator 15 is thereby added to the discriminator 13
The reproduced digital signal is phase modulated. The drive circuit 16 generates a drive signal according to the phase modulated signal to drive the electric/optical (Elo) converter 17 .

The electrical/optical converter 17 includes a laser diode, which generates an output light that varies depending on the drive signal. This output light is sent to the next stage repeater or terminal station via an optical fiber cable line.

In the terminal equipment, the digital optical signal from the optical fiber cable line is applied to an optical/electrical (0/E) converter 21 and converted into an electrical signal.

After this signal is amplified as required in an amplifier 22, it is applied to a discriminator 23 where it is discriminated by a constant darkness value to reproduce a digital signal.

The clock regeneration circuit 25 regenerates a clock signal from the amplified main signal.

On the other hand, the phase demodulator 26 phase demodulates the clock signal regenerated by the clock regeneration circuit 25 to extract the phase modulation frequency component contained therein. This signal is filtered through filters 271 to 27 . each having a different passing frequency.
The separated frequency component signals are respectively sent to the monitoring circuit 28. ~287 and is detected to monitor the presence or absence of component signals.

In this case, the passing frequency of each filter 271 to 27 is determined corresponding to the natural oscillation frequency of each repeater inserted in the line, and therefore, each repeater always oscillates at its natural frequency under normal conditions. If you are doing so,
In the terminal device, monitoring circuits 2L to 28. , all detect the signal from the corresponding filter and generate an output.

Therefore, if any repeater has a fault, signals at the oscillation frequency from repeaters closer to that repeater will be detected, but signals at the oscillation frequency from repeaters beyond the faulty repeater will not be detected. Therefore, the monitoring circuit 28. By monitoring the output status of 28, it is possible to monitor the status of each repeater in the line and locate the point of failure.

Note that even if a fault occurs not in a repeater but in a transmission path between repeaters, the range of the fault point can be determined by monitoring the natural oscillation frequencies of the repeaters before and after the fault point.

FIG. 3 illustrates an optical digital relay line to which the present invention is applied, in which an uplink line 31 and a downlink line 32 are provided between terminal stations A and B, and repeaters (1) to (n) are installed on each line. The case where ``is inserted'' is shown.

Each repeater (1) to (n) has its own oscillation frequency f, -ffI, and each oscillation frequency is set to each end station by phase modulating the main signal as described above. and at terminal stations A and B, frequencies f, ~f
7 by detecting signals on lines 31.7, respectively.
It is configured to perform 32 monitoring.

If a fault occurs between repeaters (2) and (3) in line 31, oscillation frequencies f, to f7 are detected at terminal station B, but oscillation frequency f.

, f2 are not detected, it is determined that a failure has occurred at a location further away from the repeater (3).

〔Effect of the invention〕

As explained above, according to the present invention, in a digital communication system in which a large number of repeaters are provided between terminal stations and the main signal is successively regenerated and relayed, a signal of a separate system from the main signal such as a monitoring line or a power supply line, etc. It is possible to constantly monitor the line in an in-service state without the need for transmission means or control from the terminal station, and it is also possible to quickly locate the point of failure.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of the present invention, FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 3 is a diagram illustrating an optical digital trunk line to which the present invention is applied. . 11.21...Optical/electrical (0/E) converter 12.22
... Amplifier 13.23 ... Discriminator 14 ... Oscillator 15 ... Phase modulator 16 ... Drive circuit 17 ... Electrical/optical (Elo) converter 25 ... Clock regeneration circuit 26 ...Phase demodulator 27, ~27fi...Filter 28, ~28n...Monitoring circuit Patent applicant Fujitsu Co., Ltd. Agent Patent attorney Kugobe Tamamushi (1 other person)

Claims (1)

[Claims] In a digital communication system that includes a large number of repeaters between terminal stations and sequentially reproduces and relays main signals, an oscillator (1) having a unique oscillation frequency corresponding to each repeater; The main signal regenerated in the repeater is transmitted to the oscillator (1).
Each repeater is equipped with a phase modulator (2) that performs phase modulation at an oscillation frequency, and a phase demodulator (3) that demodulates the oscillation frequency superimposed on the main signal, and monitors the demodulated frequency. A repeater monitoring system characterized in that a terminal station is equipped with a monitoring circuit (4) that monitors the oscillation frequency of each repeater station, and the line is monitored by monitoring the oscillation frequency of each relay station at the terminal station.