JPH0683153B2 - Optical subscriber line fault monitoring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a monitoring method capable of diagnosing a failure in an optical fiber transmission line system wired to each subscriber.

[Prior Art] Optical fibers have excellent characteristics such as wide band, non-induction, low loss, small diameter, and light weight. Therefore, they are expected to provide a wide variety of services by being applied to subscriber transmission lines. ing. In particular, it is desired to provide a moving image service, which is expected to be received most in the future, and research is being actively conducted in various fields.

Conventionally, as shown in FIGS. 5 (a) and 5 (b), a method of constructing an optical subscriber line has been studied (Nagata et al., "Broadband Subscriber Line Optical Transmission System", Research Practical Report, No. 1). 33
Vol. 11, 1984, p.2663-2677). Underground cable from the station to the subscriber's home (detached house, building, apartment, etc.)
It is connected through aerial cables, switching boards, connection boxes, and outdoor light lines. And it is configured to be wired in the house through the optical subscriber box. FIG. 6 (a) is an example of the configuration of a subscriber line optical transmission method, which is installed in the subscriber's house from a broadband subscriber line terminal equipment (BSLT) of the station through an optical fiber cable, an optical distribution rack, an optical fiber cable, etc. The BSU is connected to the BSU, and the BSU is connected to terminals such as a television receiver, a telephone, and a facsimile machine (Koyama et al. "Outline of field tests for broadband and closed subscriber transmission systems"). Practical Report of Research, Vol. 33, No. 3
No., 1984, p.415-425). Then, as shown in FIG.
As a failure test method in the above transmission system, a test command is received from a maintenance test device and a loopback test of loop a and loop b is executed. The loop a is a signal loopback at the user / network interface of the BSU, and is used for the purpose of discriminating whether the failure is on the user side or the network side. Further, the loop b is a signal return on the optical line side of the broadband terminal line terminating circuit (BOU) and is used for the purpose of discriminating between the in-station failure and the out-of-station failure.

[Problems to be solved by the invention]

The above failure test method is only a test method from the station side, and from the subscriber's side the transmission line network, BSU, etc. are operating normally, but it is unknown whether a failure has occurred, Further, if a failure has occurred, it is not possible to detect where it is occurring, which is very anxious for the user and also a problem from the viewpoint of safety. In particular, optical fibers are easily broken or broken by bending or external force, and optical devices (light emitting element, light receiving element, multiplexing / demultiplexing element, optical connector, optical multiplexing / branching element, lens, etc.) still have sufficient reliability. Since it is not available, it is very problematic that the user cannot monitor the failure. In addition, giving social anxiety,
There are also problems such as unfairness in that unnecessary charges are incurred even if a malfunction occurs.

An object of the present invention is to solve the above-mentioned problems and to obtain a monitoring method and an apparatus therefor capable of performing a failure diagnosis from the subscriber's home side.

[Means for Solving the Invention]

The above object is achieved by providing a failure monitoring mechanism in each subscriber's home. That is, at each subscriber's house, a means for monitoring the optical transmission output value of the optical transmission section, the optical reception output value of the optical reception section is provided, and in the state where the respective output values are below the desired values, A function is provided to selectively select either the method of giving an alarm or the method of giving an indication. Further, when the method of notifying by the above-mentioned alarm is selected, it is automatically switched to notify by the display after issuing the alarm for a predetermined time. Further, when an abnormality occurs in the signal level of the optical receiving section, it switches to the spare optical fiber cable and sends a command signal to the station side, and the station side responds to the command signal and switches to the spare optical fiber cable. Switch the line.

[Action]

A basic configuration diagram of the present invention is shown in FIG. FIG. 1 shows a block diagram of a broadband line terminating device BSU installed between subscribers' premises and terminals. The BSU has _one optical transmitter 4 for transmitting an optical signal of wavelength λ ₁ , an optical receiver 5 for receiving an optical signal of wavelength λ ₂ , and an optical receiver 6 for receiving an optical signal of wavelength λ ₃ , respectively. This is an example showing a so-called WDM bidirectional transmission device configured by one unit. An optical multiplexer / demultiplexer 1 multiplexes or demultiplexes the three-wavelength optical signal. The optical signal of the optical transmitter 4 is monitored by the optical signal monitor 11-1.
It is shown on the alarm section 12-1 or the display section 14-1. The switch 15-1 selects which of the alarm unit 12-1 and the display unit 14-1 is selected. If the alarm unit 12-1 sounds a buzzer, for example, if the buzzer keeps ringing, it will be annoying to the neighborhood in a dense subscriber area, and if it rings at night, it will be annoying as well. After that, it is better to switch to the display section. The optical signals of the optical receivers 5 and 6 are monitored by the optical signal monitor units 11-2 and 11-3 and displayed on the alarm units 12-2 and 12-3 or the display units 14-2 and 14-3. Subscriber is the alarm unit 12-
By monitoring 2 or 12-3 or the display 14-2 or 14-3, it is possible to judge whether the transmission line network or the device is normal or abnormal. Above alarm unit 12-2, 12-
3 notifies that an abnormality has occurred, for example, by a buzzer sound. Further, the display units 14-2 and 14-3 notify by turning on or off the light emitting diode display.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of an optical subscriber line fault monitoring method according to the present invention, FIG. 2 is a block diagram showing a second embodiment of the present invention, and FIG. 3 is a third embodiment of the present invention. FIG. 4 is a block diagram showing an example, and FIG. 4 is a block diagram showing a fourth embodiment of the present invention. In FIG. 1, an optical fiber cable 2 drawn into a subscriber's house through an optical subscriber box passes through an optical multiplexer / demultiplexer (WDM) 1 and an optical transmitter (OS) of a broadband line terminating device (BSU). ) 4
And the optical receivers (OR) 5 and 6 respectively, and the optical transmitter 4 and the optical receivers 5 and 6 are connected to the adapter (A
DP) 7-1, 7-2, 7-3, and is connected to the telephone 9, the television receivers 8-1, 8-2, the facsimile apparatus 10, and the like. The light output monitoring method of the light source in the light transmitter 4 is to monitor the backward emission light in the case of a semiconductor laser or to monitor the forward emission light by tapping the forward emission light with a directional coupler. When a light emitting diode is used as a light source, the forward emission light is tapped and monitored. Then, when the monitor light falls below the desired value (minimum received light power of the light receiving element on the opposite reception side + transmitted light output value that is a value of about alpha), the light emission of the light emitting diode of the display unit 14-1 is turned off. Or vice versa. The optical output monitoring method of the optical receivers 5 and 6 is performed by monitoring the output signal of the avalanche photodiode (ADP) or the photodiode (PD) used as a light receiving element. The state in which the abnormality is diagnosed is, for example, a case where an optical signal having a value equal to or smaller than a value of the minimum light receiving power of the light receiving element + about Alwa enters the light receiving element. When an abnormality occurs, the display unit 14-2 or 14-3
The light emission of the light emitting diode is turned off, or vice versa.

A second embodiment of the optical subscriber line fault monitoring method shown in FIG.
This is an example in which the monitoring mechanism is arranged not on the BSU side but on the terminal side. That is, the adapter 7-1 (7-2 or 7-
3) and optical signal monitor 11-1 (11-2 or 11-3)
And alarm unit 12-1 (12-2 or 12-3) or display unit
This is an example of an adapter 13-1 (13-2 or 13-3) with a monitoring mechanism that is integrated with 14-1 (14-2 or 14-3). The alarm unit or the display unit may be attached to the television receivers 8-1, 8-2, the telephone 9, the facsimile machine 10, and the like.

The configuration diagram shown in FIG. 3 is the third of the optical subscriber line fault monitoring method.
In the example shown, the switches 15-1, 15-2 and 15
-3 is connected to the alarm units 12-1, 12-2 and 12-3, and if an abnormality occurs, the alarm units 12-1, 12-2
And 12-3 sound the buzzer, but for a specified time (usually 10
After a few seconds, a few minutes are preferable.) After the sound, the electrical switch control circuits 16-1, 16-2, 16-3 are activated and the switch
This is a method of switching 15-1, 15-2, 15-3 to the display units 14-1, 14-2, 14-3 side. If you don't have a device like the one above, for example, when the buzzer sounds while you are sleeping in the middle of the night, it will be a nuisance if you keep ringing.
Moreover, there is a possibility that it may cause anxiety to people around. In addition, the buzzer keeps ringing when you are out. Therefore, when such a situation occurs, after the buzzer beeps for a predetermined time, the switches 15-1, 15-2, 15-3 are displayed on the display side 14-1, 14-2, 14-3.
By switching to, it is possible to solve the above problems. Furthermore, the display side 14-1, 14-2, 14-
If switched to 3, it is possible to visually monitor the abnormality later. In the above case, if it is possible to display the time of day when the abnormality has occurred, it is convenient for countermeasures against failures to be performed later, and the subscriber side can feel relieved. Electric switch control circuit 16
-1, 16-2, 16-3 can be easily realized, for example, by using the circuit technology used in a wristwatch, a timer device, or the like.

A fourth embodiment of the optical subscriber line fault monitoring method shown in FIG.
After that, when the signal level of the optical receiving unit 5 becomes equal to or lower than a desired value, that is, when the optical fiber cable 20-1 that has been used up to now becomes abnormal due to damage, breakage, breakage, or the like, a backup operation is performed. The optical fiber cable 20-2 switches,
A line switching control command signal is transmitted to the station side, and the station side responds to the above signal to switch the line to the spare optical fiber cable 20-2. If you do this,
Along with monitoring the line for abnormalities, it is possible to automatically return the abnormal state to the normal state. In FIG. 4, reference numeral 17 denotes a protection line switching control signal generator, which is an optical signal monitor 11-
When 2 is less than the desired value, that is, when an abnormality is detected, the optical transmission unit 4 sends a protection line switching control signal. When an abnormality occurs, the optical switch drive circuit 18 operates and the optical fiber cable 2 is switched by the optical switch unit 19 from the optical fiber cable 20-1 to the optical fiber cable 20-2.

The present invention is not limited to each of the above-described embodiments. For example, the number of wavelengths may be two or four or more. Further, it can be similarly applied to a system using a plurality of optical fiber cables without using wavelength division multiplexing. Further, the line switching to the spare optical fiber cable is detected by the loopback test from the station, and first, the station side switches to the spare optical fiber cable to send the control signal, and the subscriber side receives the control signal. The optical switch unit may be driven by the received signal. In this case, for example, a photodetection unit for receiving the control signal is provided on the spare optical fiber cable side of the subscriber side, and the optical switch unit 19 is operated by the signal detected by the photodetection unit, and the optical fiber cable 2 and the optical fiber optic cable 20-2.

〔The invention's effect〕

As described above, the optical subscriber line fault monitoring method according to the present invention is
In an optical subscriber line fault monitoring method of a bidirectional transmission system using an optical fiber cable between a station and a subscriber's premises, the optical signal level of both the optical transmission unit and the optical training unit of the line terminating device in the subscriber's premises, or A mechanism for monitoring the signal level obtained by converting them into an electric signal is provided in the subscriber's premises, and when the signal level is below a predetermined value, either a method of giving an alarm or a method of giving an indication is selectively used. Since the user can always monitor the failure in the subscriber's house by providing the means for selecting, it is possible to use it with peace of mind and to compensate for the safety, and it is possible to maintain fairness for the usage charge.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of an optical subscriber line fault monitoring method according to the present invention, FIG. 2 is a block diagram showing a second embodiment of the present invention, and FIG. Is a block diagram showing a third embodiment of the present invention, FIG. 4 is a block diagram showing a fourth embodiment of the present invention, and FIG. 5 (a).
Is a configuration example of a conventional optical subscriber line, FIG. 6B is a diagram showing a subscriber's home wiring, FIG. 6A is a diagram showing a configuration of a conventional subscriber line optical transmission method, and FIG. FIG. 8A is a diagram showing a conventional optical subscriber line fault test method. 4 ... Optical transmitter 5,6 ... Optical receiver 11-1, 11-2, 11-3 ... Optical signal monitor 12-1, 12-2, 12-3 ... Alarm 14-1 14-2,14-3 ... Display 15-1,15-2,15-3 ... Switch 16-1,16-2,16-3 ... Switch control circuit 17 ... Spare line switching control signal generation 18: Optical switch drive circuit 19: Optical switch 20-2: Spare optical fiber cable

Claims (4)

[Claims] 1. An optical subscriber line fault monitoring method of a bidirectional transmission system using an optical fiber cable between a station and a subscriber's premises, wherein both the optical transmitter and the optical receiver of a line terminating device in the subscriber's premises are used. A mechanism for monitoring the optical signal level or the signal level obtained by converting them into an electric signal is provided in the subscriber's house,
Optical subscriber line fault monitoring characterized in that the above mechanism is provided with a function of selectively selecting one of an alarm notification method and a display notification method when the signal level is below a desired value. Method. 2. The optical subscription according to claim 1, wherein the method of notifying by the alarm is automatically switched so as to notify by a display after a predetermined time has elapsed after the alarm is issued. Method for monitoring obstacles in the main line. 3. The optical receiving section, when the signal level of the optical receiving section becomes less than a desired value, switches to a spare optical fiber cable and transmits a control signal to the station side, and the station side performs the control. The optical subscriber line fault monitoring method according to claim 1 or 2, characterized in that a line is switched to a spare optical fiber cable according to a signal. 4. The method according to claim 3, wherein the switching of the spare optical fiber cable is automatically performed in response to a command signal in which the signal level of the optical transmitter is less than a desired value. Optical subscriber line fault monitoring method.