JP6196124B2 - Optical fiber transmission line monitoring system - Google Patents

Description

  The present invention relates to a technique for monitoring the state of an optical fiber transmission line.

  FIG. 8 shows a PON (Passive Optical Network) system that performs point-to-multipoint communication. The PON system includes a plurality of optical subscriber line termination units (ONU) 31 that connect each of the plurality of communication terminals 35 and an optical network termination unit (OLT) 41 that is connected to the backbone network. This is a point-to-multipoint connection through an optical fiber transmission line composed of an optical fiber and an optical splitter 52.

  In order to determine the communication state of the optical fiber transmission line, a communication monitoring device 6 that monitors the optical signal of the optical fiber transmission line is connected to the optical coupler 64 between the OLT 41 and the optical splitter 52 of the optical fiber transmission line. The communication monitoring device 6 includes an optical signal receiving unit 61, a signal processing unit 62, and a display control unit 63. The signal processing unit 62 detects a control frame and a data frame from the optical signal, performs signal processing, and determines link establishment and service use of the ONU 31 (Non-Patent Document 1).

  In the determination of the link establishment of the ONU 31, the detected control frame is counted for each LLID (Logical Link ID), and when the counted value is equal to or greater than a preset link establishment determination threshold, the ONU 31 having the LLID is the OLT 41. It is determined that the link has been established, and if it is less than the link establishment determination threshold, it is determined that the link has not been established. The signal processing unit 62 reads out the MAC address and LLID of each ONU 31 from the detected control frame, creates a correspondence table of the MAC address and LLID, and sets the MAC address of the ONU 31 determined that the display control unit 63 has established a link. Is displayed.

  In the service use determination, the priority set for each service (Internet connection, VoIP, etc.) from the data frame transmitted from each ONU 31 (user priority bit in the VLAN (Virtual Local Area Network) tag of the MAC frame) And the LLID of the data frame is collated with the LLID of the correspondence table created by detecting the control frame. When the LLID of the data frame is in the correspondence table and the signal processing unit 62 detects a data frame having the same priority level that is equal to or higher than a predetermined communication determination threshold, the user of the corresponding LLID uses the service. If it is less than the communication threshold, it is determined that the service is not used. Also in the determination of service use, the display control unit 63 displays the ONU 31 with the MAC address, as in the case of link establishment.

  When a failure occurs in an optical fiber transmission line, an optical pulse tester (OTDR) is often used to search for a failure location. In OTDR, it is possible to obtain information such as the position of a failure point occurring in an optical fiber transmission line, the connection loss at a connection point, and the amount of reflection (Non-Patent Document 2).

JP 2011-154294 A

Kashimura and three others, "FTTH section communication monitoring technology that realizes confirmation during call by switching work such as support transfer", NTT Technical Journal, Nippon Telegraph and Telephone Corporation, May 2009, Vol. 21, No. 5, pp.40-42 “Searching method in the event of optical fiber failure”, NTT Technical Journal, Nippon Telegraph and Telephone Corporation, October 2006, Vol. 18, No. 10, pp. 53-54 Kama and five others, “R & D that contributes to the economic and responsiveness of optical services”, NTT Technical Journal, Nippon Telegraph and Telephone Corporation, December 2006, Vol. 18, No. 12, pp.53-57 “Trouble Cases and Countermeasures in the PON System”, NTT Technical Journal, Nippon Telegraph and Telephone Corporation, October 2011, Vol. 22, No. 10, pp.62-65

  For optical fiber connection in an optical fiber transmission line, an optical connection component using a mechanical splice is used. In an optical connection component used in an optical fiber transmission line, a large gap between end faces of an optical fiber is one of the causes of performance deterioration. In optical connection parts such as mechanical splices, the end face of the optical fiber is not exactly flat, so a matching material having a refractive index equivalent to that of the core of the optical fiber is filled in a slight gap of 1 μm or less between the end faces of the optical fiber. The connection loss is usually 0.3 dB or less at a wavelength of 1.31 μm (Patent Document 1). When there is a large gap of, for example, about 100 μm between the end faces of the optical fibers, the connection loss in the optical connection component is about 1.5 dB when the alignment material fills the large gap at the beginning of connecting the optical fibers.

  Usually, an allowable loss (loss budget) between transmission apparatuses (between OLT and ONU) in an optical access system is designed with a certain margin with respect to an optical line loss between transmission apparatuses. Even if there is a large gap between the end faces of the fibers, the optical line loss between the transmission devices does not immediately exceed the allowable loss and the communication is not cut off. In most cases, normal communication can be performed between the transmission devices.

  However, since the matching material used in the connecting portion is an oil-like material, it flows due to a temperature change with time. Thereby, the air layer and the matching material can be mixed in a large gap between the end faces of the optical fibers. When this phenomenon occurs, the characteristics (connection loss, return loss) of the connection portion deteriorate significantly, and the connection loss may reach 30 dB or more. When such a significant connection loss occurs, the optical line loss between the transmission devices greatly exceeds the allowable loss, resulting in a disconnection state.

  The state in which the air layer and the matching material are mixed in a large gap between the end faces of the optical fibers greatly fluctuates the connection loss as the temperature changes. For this reason, there is a case of “sometimes disconnection” that alternately repeats a state where communication is possible and a state where communication is interrupted between transmission apparatuses.

  In such an occasional disconnection, even if OTDR is used, the location of the failure cannot be detected in a state where the connection loss is low, and as a result, the time required from the occurrence of the failure to the failure recovery becomes longer. .

  An OTDR can be attached to the optical coupler 64 on the OLT 41 side, and an automatic test can be performed when an error occurs based on the alarm information of the transmission device. However, if there is a failure in the optical fiber section in the lower section of the optical splitter 52 In this case, the reflected light is superimposed from each optical fiber section on the lower side of the optical splitter 52, and it is not easy to find a correct failure location. Moreover, on-site assembly connectors called “FA connectors” and “FAS connectors” are often used to connect optical fibers in the lower section of the optical splitter 52 (Non-patent Document 3). The field assembly connector has a mechanism equivalent to the mechanical splice described above, and the quality differs greatly depending on the operator as compared with the connector assembled at the factory, and is likely to cause a failure.

  In addition, the case of “several interruptions” is not always caused by optical connection parts. For example, the effects of electromagnetic interference (noise) generated from household appliances such as refrigerators and microwave ovens near the transmission device, and the same PON The influence of abnormal signals from other user devices under the control is also conceivable (Non-Patent Document 4).

  The present invention has been made in view of the above, and it is an object of the present invention to specify a failure location more quickly even when communication is possible and communication is interrupted alternately.

An optical fiber transmission line monitoring system according to the present invention measures the state of an optical fiber transmission line between transmission apparatuses connected by an optical fiber transmission line in which one optical fiber is branched into a plurality of optical fibers by an optical splitter. An optical fiber transmission line monitoring system , which is connected to a first optical fiber transmission line monitoring device connected to an optical fiber after branching of the optical fiber transmission line and an optical fiber before branching of the optical fiber transmission line A second optical fiber transmission line monitoring device, the first optical fiber transmission line monitoring device comprising: a first optical coupler disposed in an optical fiber after branching of the optical fiber transmission line; A first error detecting means for detecting an error occurring in a fiber transmission line; and when the first error detecting means detects an error, the optical fiber is passed through the first optical coupler. It includes a first OTDR incident test light to the driver transmission path for measuring and recording the state of the optical fiber transmission line, and said second optical fiber transmission line monitoring apparatus, the light A second optical coupler arranged in the optical fiber before branching of the fiber transmission line, a second error detection means for detecting an error occurring in the optical fiber transmission line, and the second error detection means And a second optical pulse tester for measuring and recording the state of the optical fiber transmission line by inputting test light to the optical fiber transmission line via the second optical coupler when detected. Then, the wavelength λ1 of the test light of the first optical pulse tester and the wavelength λ2 of the test light of the second optical pulse tester are different from each other, and the test light having the wavelength λ2 is sent to the first optical pulse tester. An optical filter for cutting off the second optical pulse An optical filter for blocking the test light of wavelength λ1 in the test device, the state of the optical fiber after the branch is measured by the first optical pulse tester, and the optical fiber before the branch is measured by the second optical pulse tester. The condition of the optical fiber is measured .

In the optical fiber transmission line monitoring system , the first error detection means acquires error information from a transmission device connected to the branched optical fiber.

In the optical fiber transmission line monitoring system , the first error detection means is connected to the first optical coupler and receives communication light output from a transmission device connected to the branched optical fiber, It is characterized by detecting the intensity of the communication light or acquiring communication alarm information transmitted / received by the communication light.

  According to the present invention, it is possible to identify a failure location more promptly even when communication is possible and communication is interrupted alternately.

1 is an overall configuration diagram including an optical fiber transmission line monitoring device in a first embodiment. It is a functional block diagram which shows the structure of the optical fiber transmission line monitoring apparatus in 1st Embodiment. It is a functional block diagram which shows the structure of the optical fiber transmission-line monitor apparatus in 2nd Embodiment. It is a functional block diagram which shows the structure of the optical fiber transmission-line monitoring apparatus in 3rd Embodiment. It is a whole block diagram including the optical fiber transmission-line monitor apparatus in 4th Embodiment. It is a functional block diagram which shows the structure of the optical fiber transmission-line monitor apparatus in 4th Embodiment. It is a functional block diagram which shows the structure of the optical fiber transmission-line monitor apparatus in 5th Embodiment. 1 is an overall configuration diagram of a PON system that performs point-to-multipoint communication. FIG.

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

[First Embodiment]
FIG. 1 is an overall configuration diagram including an optical fiber transmission line monitoring device according to the first embodiment. In the figure, a user home, a communication facility building, and a maintenance base are shown.

  In the communication facility building, an OLT 41 and a termination frame 42 called IDM (Integrated distribution module) are installed. An optical splitter 44 and an optical coupler (not shown) are installed in the termination rack 42. Between the OLT 41 and the optical splitter 44, an optical filter 43 that blocks test light is provided.

  The optical fiber extending from the communication facility building is branched by an optical splitter 52 installed in an outside optical closure 51 and connected to the optical rosette 32 at the user's home by an optical drop cable.

  An optical fiber transmission line monitoring device 1 and an ONU 31 are installed in the user's home. The optical fiber drawn to the optical rosette 32 by the optical drop cable is connected to the ONU 31 via the optical fiber transmission line monitoring device 1. The optical rosette 32 is also provided with an optical filter 33 that shields the test light.

  The connectors 34A, 34B, 53A, 53B, and the ends of the optical drop cable connecting the optical splitter 52 and the optical closet 32 at the user's home are connected to the optical cable extending from the communication facility building and the external optical splitter 52. 54A and 54B are connected. Among these, the connector 53A connected to the optical splitter 52 from the communication facility building and the connectors 54A and 34A at both ends of the optical drop cable are connected using the on-site assembly connector. Although not shown, a mechanical splice or fusion splicing may be performed between the optical drop cables between the optical closure 51 and the optical rosette 32 at the time of trouble transfer work or failure repair.

  At the maintenance site, the communication status of the communication system shown in FIG. 1 can be known from the communication alarm information between the OLT 41 and the ONU 31. If the communication between the OLT 41 and the ONU 31 is not normal, the OTDR is connected to the optical coupler installed in the communication equipment building to search for a fault location in the optical fiber from the communication equipment building to the optical splitter 52, and the OTDR is installed in the user's home. Install and search for a failure position in the optical fiber from the ONU 31 to the optical splitter 52.

  However, in the case of mechanical splices in field assembly connectors such as connectors 34A, 53A, and 54, when the air layer and bonding material are mixed in a large gap between the end faces of the optical fibers, the connection loss may fluctuate greatly with changes in temperature. Yes, as described above, the connection loss is not always large at the time of measurement by OTDR. Therefore, in this embodiment, the optical fiber transmission line monitoring device 1 is installed in the user's house, and when a communication error is detected, the failure location is searched by OTDR.

  FIG. 2 is a functional block diagram showing a configuration of the optical fiber transmission line monitoring device 1 according to the first embodiment. The optical fiber transmission line monitoring device 1 shown in the figure includes an optical coupler 11, an OTDR 12, and an error detection unit 13.

  The optical coupler 11 includes three ports, an A port, a B port, and a C port. An optical fiber connected to the OLT 41 is connected to the A port, an ONU 31 is connected to the B port, and an OTDR 12 is connected to the C port. The A port and the B port have wavelength characteristics that allow communication light between the OLT 41 and the ONU 31 to pass therethrough, and the C port and A port have wavelength characteristics that allow the test light from the OTDR 12 to pass through.

  The OTDR 12 makes an optical pulse incident on the optical fiber transmission line via the optical coupler 11, measures the optical power reflected at each point of the optical fiber transmission line and returning to the incident end, and obtained by measurement. The waveform data is stored in the storage means of the OTDR 12.

  The error detection unit 13 receives a notification of a communication error between the OLT 41 and the ONU 31 from the ONU 31 and issues an instruction to measure the optical fiber transmission path to the OTDR 12.

  Next, the operation of the optical fiber transmission line monitoring device 1 in the first embodiment will be described.

  When the error detection unit 13 receives a notification of a communication error between the OLT 41 and the ONU 31 from the ONU 31 (step S11), the error detection unit 13 issues an optical fiber transmission line measurement instruction to the OTDR 12 (step S12).

  The OTDR 12 enters an optical pulse into the optical fiber transmission line via the optical coupler 11 and measures the state of the optical fiber transmission line (step S13).

  At the maintenance base, the communication state between the OLT 41 and the ONU 31 is monitored. When a communication error occurs between the OLT 41 and the ONU 31, the optical fiber transmission line monitoring device 1 in the user's home is collected, and the failure location is found from the OTDR waveform data at the time of the error occurrence. If it can be confirmed from the OTDR waveform data that an increase in the connection loss of the optical connection member and a decrease in the return loss are confirmed, it can be determined that a communication error has occurred due to the optical fiber transmission line.

  When the communication system is GE-PON, the communication light from the ONU 31 to the OLT 41 uses the 1310 nm band, and the communication light from the OLT 41 to the ONU 31 uses the 1490 nm band. Therefore, the wavelength of the optical pulse output from the OTDR 12 is, for example, 1550 nm or The 1650 nm band is preferred. Further, an optical filter that shields the 1310 nm or 1490 nm band is required so that the communication light of the OLT 41 and the ONU 31 does not enter the OTDR 12.

  As described above, according to the present embodiment, the error detection unit 13 that detects an error occurring in the optical fiber transmission line at the user's home, and the optical fiber transmission when the error detection unit 13 detects the error. When the optical fiber transmission line monitoring device 1 including the OTDR 12 that measures the state of the optical fiber transmission line by entering the test light into the line is arranged, the communication is possible and the communication is interrupted alternately. Even when the communication is interrupted, the state of the optical fiber transmission line can be measured and recorded from the user's home side, and the failure location can be identified more quickly.

[Second Embodiment]
In the communication system shown in FIG. 1, when the ONU 31 cannot correctly receive the communication light from the OLT 41, the ONU 31 may stop emitting the communication light. Therefore, the optical fiber transmission line monitoring device 1 of the second embodiment includes an optical power meter 14 instead of the error detection unit 13 of the optical fiber transmission line monitoring device 1 of the first embodiment, and includes an ONU 31. The occurrence of a communication error between the OLT 41 and the ONU 31 is detected by confirming the received light level of the communication light. Since the overall configuration diagram of the communication system is the same as that of the first embodiment, description thereof is omitted here.

  FIG. 3 is a functional block diagram showing the configuration of the optical fiber transmission line monitoring device 1 according to the second embodiment. The optical fiber transmission line monitoring device 1 shown in the figure includes an optical coupler 11, an OTDR 12, and an optical power meter 14.

  The optical coupler 11 has four ports, A port, B port, C port, and D port, an optical fiber connected to the OLT 41 at the A port, an ONU 31 at the B port, an OTDR 12 at the C port, and an optical power meter 14 at the D port. Each is connected. The A port and the B port have wavelength characteristics that allow communication light between the OLT 41 and the ONU 31 to pass therethrough, and the C port and A port have wavelength characteristics that allow the test light from the OTDR 12 to pass through. Further, between the B port and the D port, there is a wavelength characteristic through which only communication light output from the ONU 31 is transmitted.

  The optical power meter 14 confirms the light reception level of the communication light output from the ONU 31. If the light reception level of the communication light from the ONU 31 is significantly reduced or cannot be detected, the optical power meter 14 issues an instruction to measure the optical fiber transmission path to the OTDR 12.

  The optical fiber transmission line monitoring device 1 according to the second embodiment detects a communication error by confirming the light reception level of the communication light output from the ONU 31, and therefore no connection is required to receive a communication error notification from the ONU 31. It is.

  Next, the operation of the optical fiber transmission line monitoring device 1 in the second embodiment will be described.

  The optical power meter 14 receives the communication light from the ONU 31 via the optical coupler 11 and detects the received light level (step S21). If the detected received light level is equal to or lower than a predetermined value, the optical power meter 14 sends the optical fiber transmission line to the OTDR 12. A measurement instruction is issued (step S22).

  The OTDR 12 enters the optical pulse into the optical fiber transmission line via the optical coupler 11 and measures the state of the optical fiber transmission line (step S23).

  Similar to the first embodiment, when the occurrence of a communication error between the OLT 41 and the ONU 31 is detected at the maintenance base, the optical fiber transmission line monitoring device 1 at the user's home is collected, and from the OTDR waveform data at the time of the error occurrence Find the fault location.

  As in the first embodiment, the wavelength of the optical pulse output from the OTDR 12 is, for example, a 1550 nm or 1650 nm band so that the communication light of the OLT 41 or the ONU 31 does not enter the OTDR 12 so that it differs from the wavelength of the communication light. , An optical filter that shields the 1310 nm and 1490 nm bands is required.

  As described above, according to the present embodiment, the optical fiber transmission line monitoring device 1 installed at the user's home confirms the light reception level of the communication light output from the ONU 31 and the light reception level of the communication light from the ONU 31 is If the optical power meter 14 that gives an instruction to measure the optical fiber transmission path to the OTDR 12 when it is greatly reduced or cannot be detected, the ONU 31 that has stopped receiving the communication light from the OLT 41 correctly stopped emitting the communication light. The state of the optical fiber transmission line can be measured and recorded when an error occurs in the optical fiber transmission line.

[Third Embodiment]
The optical fiber transmission line monitoring device 1 of the third embodiment is a communication monitoring unit instead of the error detection unit 13 that receives a communication error notification from the ONU 31 of the optical fiber transmission line monitoring device 1 of the first embodiment. 15, communication alarm information between the OLT 41 and the ONU 31 is acquired from the communication light from the ONU 31. Since the overall configuration diagram of the communication system is the same as that of the first embodiment, description thereof is omitted here.

  FIG. 4 is a functional block diagram showing the configuration of the optical fiber transmission line monitoring device 1 according to the third embodiment. The optical fiber transmission line monitoring device 1 shown in the figure includes an optical coupler 11, an OTDR 12, and a communication monitoring unit 15.

  The optical coupler 11 has four ports, A port, B port, C port, and D port, an optical fiber connected to the OLT 41 at the A port, an ONU 31 at the B port, an OTDR 12 at the C port, and a communication monitor unit 15 at the D port. Each is connected. The A port and the B port have wavelength characteristics that allow communication light between the OLT 41 and the ONU 31 to pass therethrough, and the C port and A port have wavelength characteristics that allow the test light from the OTDR 12 to pass through. Further, between the B port and the D port, there is a wavelength characteristic through which only communication light output from the ONU 31 is transmitted.

  The communication monitor unit 15 acquires communication alarm information between the OLT 41 and the ONU 31 from the communication light output from the ONU 31, confirms the communication status, and issues an instruction to measure the optical fiber transmission path to the OTDR 12 when a communication error is detected.

  Since the optical fiber transmission line monitoring device 1 in the third embodiment detects a communication error by acquiring communication alarm information from the communication light output from the ONU 31, a connection for receiving a communication error notification from the ONU 31 is performed. It is unnecessary.

  Next, the operation of the optical fiber transmission line monitoring device 1 in the third embodiment will be described.

  The communication monitor unit 15 receives communication light from the ONU 31 via the optical coupler 11 to acquire communication alarm information (step S31). When a communication error is detected, the communication monitor unit 15 instructs the OTDR 12 to measure the optical fiber transmission path. (Step S32).

  The OTDR 12 enters an optical pulse into the optical fiber transmission line via the optical coupler 11 and measures the state of the optical fiber transmission line (step S33).

  Similar to the first embodiment, when the occurrence of a communication error between the OLT 41 and the ONU 31 is detected at the maintenance base, the optical fiber transmission line monitoring device 1 at the user's home is collected, and from the OTDR waveform data at the time of the error occurrence Find the fault location.

  As in the first embodiment, the wavelength of the optical pulse output from the OTDR 12 is, for example, a 1550 nm or 1650 nm band so that the communication light of the OLT 41 or the ONU 31 does not enter the OTDR 12 so that it differs from the wavelength of the communication light. , An optical filter that shields the 1310 nm and 1490 nm bands is required.

  As described above, according to the present embodiment, the optical fiber transmission line monitoring device 1 installed in the user's home acquires the communication alarm information between the OLT 41 and the ONU 31 from the communication light output from the ONU 31 and displays the communication status. Measure and record the state of the optical fiber transmission line when an error occurs in the optical fiber transmission line by providing the communication monitor unit 15 that confirms and detects an optical fiber transmission line measurement instruction to the OTDR 12 when a communication error is detected Can do.

[Fourth Embodiment]
FIG. 5 is an overall configuration diagram including the optical fiber transmission line monitoring apparatus in the fourth embodiment. In the fourth embodiment, an optical fiber transmission line monitoring device 2 is also arranged in a communication facility building, and when a communication error is detected, optical fiber transmission is performed by OTDR from both the user home side and the communication facility building side. Measure the road. The optical fiber transmission line monitoring device 1 arranged in the user's home may use any configuration of the first to third embodiments.

  FIG. 6 is a functional block diagram showing the configuration of the optical fiber transmission line monitoring device 2 in the fourth embodiment. The optical fiber transmission line monitoring device 2 shown in the figure includes an error detection unit 21 and an OTDR 22. The optical fiber transmission line monitoring device 2 is connected to an optical coupler 45 and an OLT 41 arranged in the termination rack 42.

  The optical coupler 45 includes three ports, an X port, a Y port, and a Z port. An optical fiber connected to the OLT 41 is connected to the X port, an optical fiber connected to the ONU 31 is connected to the Y port, and an OTDR 22 is connected to the Z port. The X port and the Y port have wavelength characteristics that allow communication light between the OLT 41 and the ONU 31 to pass therethrough, and the Y port and Z port have wavelength characteristics that allow the test light from the OTDR 22 to pass through.

  The error detection unit 21 receives a notification of a communication error between the OLT 41 and the ONU 31 from the OLT 41 and issues an instruction to measure the optical fiber transmission path to the OTDR 22.

  The OTDR 22 measures the optical fiber on the ONU 31 side by making an optical pulse incident on the optical fiber transmission line via the optical coupler 45, and stores the OTDR waveform data obtained by the measurement in the storage means of the OTDR 22.

  Next, the operation of the optical fiber transmission line monitoring device 2 in the fourth embodiment will be described.

  When receiving a notification of a communication error between the OLT 41 and the ONU 31 from the OLT 41 (step S41), the error detection unit 21 issues an optical fiber transmission path measurement instruction to the OTDR 22 (step S42).

  The OTDR 22 enters the optical pulse into the optical fiber transmission line via the optical coupler 45 and measures the state of the optical fiber transmission line (step S43).

  When a communication error occurs, the optical fiber transmission line monitoring device 1 disposed in the user's house also measures the optical fiber transmission line, so the OTDR 12 at the user's house measures the optical fiber from the ONU 31 to the outside optical splitter 52, and performs communication. The facility building OTDR 22 may measure the optical fiber from the OLT 41 to the outside optical splitter 52. Therefore, it is desirable that the OTDR 12 of the optical fiber transmission line monitoring device 1 installed at the user's home is measured with a narrower pulse width and higher resolution.

  When the optical fiber transmission line monitoring device 2 is installed in a communication equipment building and the optical fiber transmission line is measured from both the user home side and the communication equipment building side, the light source wavelength of the OTDR 12 at the user home is λ1, It is desirable that the light source wavelength of the OTDR 22 is λ2 to vary the wavelength of the test light, the OTDR 12 includes an optical filter that blocks the wavelength of λ2, and the OTDR 22 includes an optical filter that blocks the wavelength of λ1. In many cases, an optical filter 33 that blocks test light in the 1650 nm band is disposed in the optical rosette 32, and the light source wavelength λ1 uses the 1550 nm band or 1610 nm band that passes through the optical filter 33, and the light source wavelength λ2 Preferably uses the 1650 nm band.

  As described above, according to the present embodiment, the optical fiber transmission line monitoring device 1 on the user's home side is provided from the ONU 31 to the optical splitter 52 by providing the optical fiber transmission line monitoring device 2 in the communication facility building. The optical fiber transmission line monitoring device 2 on the communication equipment building side only needs to measure from the OLT 41 to the optical splitter 52, and since it is not necessary to obtain a high dynamic range in the OTDRs 12 and 22, the pulse width is narrowed, etc. The resolution can be increased and more accurate measurement can be performed.

  According to this embodiment, even if the OTDRs 12 and 22 use different test light wavelengths from each other at the same time from the user's home side and the communication equipment building side, the measurement results are affected. Measure without giving.

[Fifth Embodiment]
The optical fiber transmission line monitoring device 2 of the fifth embodiment is a communication monitoring unit instead of the error detection unit 21 that receives a communication error notification from the OLT 41 of the optical fiber transmission line monitoring device 2 of the fourth embodiment. The communication alarm information between the OLT 41 and the ONU 31 is acquired from the communication light from the ONU 31. Since the overall configuration diagram of the communication system is the same as that of the fourth embodiment, description thereof is omitted here.

  FIG. 7 is a functional block diagram showing the configuration of the optical fiber transmission line monitoring device 2 in the fifth embodiment. The optical fiber transmission line monitoring device 1 shown in the figure includes an OTDR 22 and a communication monitor unit 23.

  The optical coupler 45 includes three ports, an X port, a Y port, and a Z port. An optical fiber connected to the OLT 41 is connected to the X port, an optical fiber connected to the ONU 31 is connected to the Y port, and the OTDR 22 and the communication monitor unit 23 are connected to the Z port. The The X port and the Y port have wavelength characteristics that allow communication light between the OLT 41 and the ONU 31 to pass therethrough, and the Y port and Z port have wavelength characteristics that allow the test light from the OTDR 22 and the communication light from the ONU 31 to pass through. have.

  The communication monitor unit 23 acquires communication alarm information between the OLT 41 and the ONU 31 from the communication light output from the ONU 31, confirms the communication status, and issues an instruction to measure the optical fiber transmission path to the OTDR 22 when a communication error is detected.

  Since the optical fiber transmission line monitoring device 2 in the fifth embodiment detects a communication error by acquiring communication alarm information from the communication light output from the ONU 31, a connection for receiving a communication error notification from the OLT 41 is established. It is unnecessary.

  Next, the operation of the optical fiber transmission line monitoring device 2 in the fifth embodiment will be described.

  The communication monitor unit 23 receives communication light from the ONU 31 through the optical coupler 45 to acquire communication alarm information (step S51). When a communication error is detected, the communication monitor unit 23 instructs the OTDR 22 to measure the optical fiber transmission path. (Step S52).

  The OTDR 22 enters the optical pulse into the optical fiber transmission line via the optical coupler 45 and measures the state of the optical fiber transmission line (step S53).

  Also in the fifth embodiment, the OTDR 12 at the user's home measures the optical fiber from the ONU 31 to the outside optical splitter 52, and the OTDR 22 at the communication equipment building measures the optical fiber from the OLT 41 to the outside optical splitter 52. do it.

  Further, test light of different wavelengths is used with the light source wavelengths of OTDRs 12 and 22 as λ1 and λ2, and OTDRs 12 and 22 are each provided with an optical filter that blocks the wavelengths of the test light of the other OTDRs 12 and 22.

DESCRIPTION OF SYMBOLS 1 ... Optical fiber transmission line monitoring apparatus 11 ... Optical coupler 12 ... OTDR
DESCRIPTION OF SYMBOLS 13 ... Error detection part 14 ... Optical power meter 15 ... Communication monitoring part 2 ... Optical fiber transmission line monitoring apparatus 21 ... Error detection part 22 ... OTDR
23 ... Communication monitor 31 ... ONU
32 ... Optical rosette 33 ... Optical filter 34A, 34B ... Connector 35 ... Communication terminal 41 ... OLT
DESCRIPTION OF SYMBOLS 42 ... Termination frame 43 ... Optical filter 44 ... Optical splitter 45 ... Optical coupler 51 ... Optical closure 52 ... Optical splitter 53A, 53B, 54A, 54B ... Connector 6 ... Communication monitoring apparatus 61 ... Optical signal receiving part 62 ... Signal processing part 63: Display control unit 64: Optical coupler

Claims (3)

An optical fiber transmission line monitoring system for measuring a state of an optical fiber transmission line between transmission apparatuses connected by an optical fiber transmission line in which one optical fiber is branched into a plurality of optical fibers by an optical splitter,
A first optical fiber transmission line monitoring device connected to the optical fiber after branching of the optical fiber transmission line, and a second optical fiber transmission line monitoring device connected to the optical fiber before branching of the optical fiber transmission line; Have
The first optical fiber transmission line monitoring device is:
A first optical coupler disposed in the optical fiber after branching of the optical fiber transmission line;
First error detection means for detecting an error occurring in the optical fiber transmission line;
When the first error detecting means detects an error, the test light is incident on the optical fiber transmission line via the first optical coupler, and the state of the optical fiber transmission line is measured and recorded. 1 optical pulse tester,
The second optical fiber transmission line monitoring device is:
A second optical coupler disposed in the optical fiber before branching of the optical fiber transmission line;
Second error detection means for detecting an error occurring in the optical fiber transmission line;
When the second error detecting means detects an error, a test light is incident on the optical fiber transmission line via the second optical coupler, and a state of the optical fiber transmission line is measured and recorded. Two optical pulse testers,
The wavelength λ1 of the test light of the first optical pulse tester and the wavelength λ2 of the test light of the second optical pulse tester are different wavelengths,
The first optical pulse tester comprises an optical filter that blocks test light having a wavelength λ2.
The second optical pulse tester includes an optical filter that blocks test light having a wavelength λ1.
An optical fiber transmission line characterized in that the state of the optical fiber after branching is measured by the first optical pulse tester, and the state of the optical fiber before branching is measured by the second optical pulse tester. Monitor system. 2. The optical fiber transmission line monitoring system according to claim 1, wherein the first error detection means acquires error information from a transmission device connected to the branched optical fiber. The first error detection means is connected to the first optical coupler, receives communication light output from a transmission device connected to the branched optical fiber, and detects the intensity of the communication light or 2. The optical fiber transmission line monitoring system according to claim 1, wherein communication alarm information transmitted and received by communication light is acquired.

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