JP4851380B2 - Optical fiber identification method and identification apparatus - Google Patents

Description

  The present invention relates to an optical core identification method and an optical core identification device used for optical fiber line contrast, and more particularly to an optical core identification used to identify an unused core in a PON communication system. The present invention relates to a method and an optical fiber identification device.

  As a communication system using an optical fiber, PON (Passive Optical Network) communication as shown in FIG. 4 is known. In the PON communication system 900, a downstream optical signal λ91 from an OLT (Optical Line Terminal) 901 is branched by a splitter 902 and transmitted to a plurality of user side ONUs (Optical Network Units) 903. Each ONU selects and acquires only the optical signal addressed to itself. The downstream optical signal λ91 includes a signal for controlling the transmission timing of the upstream optical signal λ92 transmitted from each ONU 903.

  Each optical signal λ 92 transmitted from each ONU 903 is multiplexed by the splitter 902 and input to the OLT 901 in a signal sequence at a timing designated by the OLT 901. In the OLT 901, the upstream optical signal λ 92 is divided into ONU 903 optical signals.

  In the PON communication system 900 having the above-described configuration, an apparatus disclosed in, for example, Patent Document 1 is known as an apparatus that monitors an optical line that performs optical communication and performs maintenance when an abnormality occurs. This is to monitor the optical line by sending test light from the station side to the established optical line and confirming that it is reflected by the termination provided in the ONU on the user side and returns to the station side again. is doing.

  On the other hand, when a new unused line that is not opened is newly used, an unused core cannot be selected using the above-described apparatus. For example, as shown in FIG. 6A, when a line is opened by newly installing an ONU at the position of the closure unit 920 with respect to the core wire previously wired to the splitter 902, the ONU 903 is already installed and used. It is necessary to identify and disconnect unused cores that are unused lines so as not to accidentally disconnect the cores that are used (working cores).

Conventionally, in order to identify an unused core wire, as shown in FIG. 6B, a core wire to be newly installed is selected by going to the terminal portion of the installed optical fiber cable 910, and then the core wire is selected therefrom. A test light for line contrast is incident, and this test light is detected by using the core control machine at the closure part 920 at the planned cutting position to identify the core. Thus, after identifying the core wire to be newly installed, this core wire is cut and the ONU 903a is newly installed (FIG. 6C).
Japanese Patent No. 3042594

  However, the above conventional techniques have the following problems. In the method in which the test light is incident from the end of the optical fiber cable and the optical fiber is contrasted, the work location becomes two locations, that is, the end portion of the optical fiber cable and the planned cutting location. There is a problem that the cost becomes high. Further, in the end portion of the optical fiber cable, it is necessary to select a core wire to which the test light is incident from among a plurality of core wires, and it takes time to connect a light source.

  As mentioned above, the core contrast work for selecting the core to be newly established is a very time-consuming work. Therefore, in actual operation, only the design data such as equipment drawings is used for the corresponding core. In some cases, the core control work using the core control machine may be omitted. For this reason, there is a problem that the core wire is erroneously selected and cut.

  Therefore, the present invention has been made to solve these problems, and provides an optical core identification method and an optical core identification apparatus capable of simply and reliably identifying an unused core that can be newly installed in an ONU. The purpose is to do.

  According to a first aspect of the optical fiber identification method of the present invention, an OLT for transmitting an optical signal having a first wavelength from the station side and an ONU for transmitting an optical signal having a second wavelength on the user side are provided with a splitter. In a PON communication system configured by connecting with an optical fiber cable via an optical fiber cable, an unused core in which the ONU can be newly installed from a plurality of core wires in the optical fiber cable routed between the splitter and the ONU An optical core identification method for identifying a line (hereinafter referred to as a newly installed core), the optical signal having the first wavelength transmitted from the OLT toward the ONU (hereinafter referred to as a downward direction) Hereinafter referred to as downstream optical signal) and an optical signal transmitted from the ONU side toward the OLT side (hereinafter referred to as upstream direction) (hereinafter referred to as upstream optical signal) downstream from the splitter, Serial downlink optical signal is detected, and the upstream optical signal and judging with the new target core wire said core wire when it is undetected.

  Another aspect of the optical fiber identification method of the present invention is characterized in that the upstream optical signal is an optical signal of the second wavelength transmitted from the ONU in the upstream direction.

  In another aspect of the optical fiber identification method of the present invention, the OLT includes a test light emitting unit having a third wavelength, and the ONU reflects the test light having the third wavelength. The test light is transmitted from the OLT by the test light emitting means in the downstream direction, and the test light reflected by the reflecting means and transmitted in the upstream direction is measured as the upstream optical signal. It is characterized by.

  According to another aspect of the optical fiber identification method of the present invention, the ONU is provided with reflecting means for reflecting the test light of the third wavelength, and the downstream optical signal transmitted from the OLT is detected. In addition, when the upstream optical signal having the second wavelength transmitted from the ONU is not detected, the core wire is determined to be a temporary new target core wire, and the temporary new target core wire is disconnected. When the test light having the third wavelength is incident from the end portion in the downstream direction and the test light is not detected as the upstream optical signal, the temporary new core wire is determined as the new target core wire. It is characterized by doing.

  In another aspect of the optical fiber identification method of the present invention, another reflection means for reflecting the downstream optical signal is provided in advance at the other end of the optical fiber opposite to the one connected to the splitter. A first measurement value is obtained by measuring the upstream optical signal transmitted through the core wire at a predetermined measurement position downstream of the splitter, and the first measurement value is less than a predetermined threshold value. When it is small, the downstream light signal is reflected by the other reflecting means and reflected light transmitted in the upstream direction is measured at the measurement position to obtain a second measured value, and the downstream side of the measurement position The reflected light when a loss of a predetermined magnitude is applied to the core wire is measured to obtain a third measurement value, and when the second measurement value and the third measurement value are different, the heart A line is determined to be the newly installed core.

  According to a first aspect of the optical fiber identification device of the present invention, an OLT for transmitting an optical signal having a first wavelength from the station side and an ONU for transmitting an optical signal having a second wavelength on the user side are provided with a splitter. In a PON communication system configured by connecting with an optical fiber cable via an optical fiber cable, an unused core in which the ONU can be newly installed from a plurality of core wires in the optical fiber cable routed between the splitter and the ONU An optical fiber identification device for identifying a line (hereinafter referred to as a newly installed core), which is provided downstream from the splitter and is transmitted from the OLT toward the ONU (hereinafter referred to as a downward direction). A first detector that detects an optical signal of the first wavelength (hereinafter referred to as a downstream optical signal), and an optical signal (hereinafter referred to as an upstream direction) transmitted from the ONU side to the OLT side (hereinafter referred to as an upstream direction). so A detection unit having a second detector for detecting an upstream optical signal), and each measurement value is input from the first detector and the second detector of the detection unit; And a determination processing unit that determines the core wire when the downstream optical signal is detected by the second detector and the upstream optical signal is not detected by the second detector as the new target core wire. It is characterized by that.

  Another aspect of the optical fiber identification device of the present invention is characterized by further comprising test light emitting means for emitting test light having a third wavelength.

  According to another aspect of the optical fiber identification device of the present invention, the first detector and the second detector each selectively receive the downstream optical signal and the upstream optical signal. It is characterized by providing.

  According to another aspect of the optical fiber identification device of the present invention, the optical fiber identification device further includes loss addition means for adding a loss of a predetermined magnitude to the core, and the first detector and the second detector include A filter for blocking reflected light reflected by another reflecting means provided at an end of the core wire so that the downstream signal and the downstream signal are detachably provided, and the determination processing unit includes the first processing unit. A first measurement value obtained by attaching the filter to the detector and the second detector and measuring the upstream optical signal by the second detector; and the first detector and the second detection A second measurement value obtained by removing the filter from the detector and measuring the reflected light by the second detector; and removing the filter from the first detector and the second detector and adding the loss. And enter the third measured value added with the loss in Then, the core wire determined that the first measurement value is smaller than a predetermined threshold and the second measurement value and the third measurement value are different is determined as the newly-installed core wire. It is characterized by that.

  According to the present invention, a downstream optical signal transmitted from the OLT is detected, and an upstream optical signal transmitted in the OLT direction from the ONU side is not detected. Therefore, it is possible to provide an optical fiber identification method and an optical fiber identification device capable of simply and reliably identifying a newly installed core wire of an ONU.

  An optical core identification device and identification method according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

  An optical fiber identification method and an optical fiber identification device according to an embodiment of the present invention will be described in detail with reference to FIG. FIG. 2 is an enlarged view of a part of the PON communication system 100 configured by connecting the OLT 111 installed in the station 110 and the ONU 120 installed on the user side with the optical fiber cable 140 via the splitter 130. It is a schematic diagram. Although only one splitter 130 is shown in FIG. 2, a similar splitter is connected to the optical fiber cable 140 connected to the OLT 111 to other cores other than the core connected to the splitter 130. ing. Further, another splitter may be connected in series in the downstream direction of the splitter 130 and further demultiplexed. The core identification method of the present embodiment is to identify the core of the optical fiber cable 140a connected to the most downstream splitter 130.

  From the OLT 111, an optical signal (hereinafter referred to as a downstream optical signal) of a predetermined wavelength (hereinafter referred to as a downstream optical signal) is transmitted toward the ONU 120 (hereinafter referred to as a downstream direction), and this downstream optical signal is demultiplexed by the splitter 130. And transmitted to the ONU 120 on each user side. On the other hand, from the ONU 120 installed on each user side, an optical signal (hereinafter referred to as upstream optical signal) having a wavelength (λ2) different from the wavelength of the downstream optical signal is directed toward the OLT 111 (hereinafter referred to as upstream direction). The upstream optical signal from each ONU 120 is multiplexed by the splitter 130 and transmitted to the OLT 111. As the wavelength λ1 of the downstream optical signal and the wavelength λ2 of the upstream optical signal, for example, laser beams of 1.49 μm and 1.31 μm are used, respectively.

  Termination 121 is provided for all ONUs 120 installed on the user side. This termination 121 has a characteristic of reflecting light having a wavelength different from the above wavelengths λ1 and λ2 (hereinafter referred to as λ3), and is transmitted from the OLT 111 for maintenance of the PON communication system 100, for example. The test light having the wavelength λ3 is reflected and returned to the OLT 111 again. As test light having a wavelength λ3, for example, laser light having a wavelength of 1.65 μm can be used.

  As the optical fiber cable 140a connected in the downstream direction of the splitter 130, for example, a 24 single-core cable can be used. In the downward direction of the splitter 130, not only the currently used core wire (hereinafter referred to as a working core wire) but also a number of core wires including the expected number of future demands are connected in advance to the splitter 130. be able to. Therefore, in the optical fiber cable 140a connected in the downward direction of the splitter 130, in addition to the active core wire, an unused core wire that is connected to the splitter 130 but also a core wire that is not connected to the splitter 130 is included. include.

  On the downstream end face of the optical fiber cable 140a connected to the splitter 130, another reflecting means such as mirror cutting is provided in advance, and the light transmitted in the downstream direction is unused at the end of the unused core wire. Treated to reflect Fresnel. This processing is performed when the optical fiber cable 140a is laid, for example, and is maintained so that the end face state is appropriately maintained thereafter.

  In the optical fiber identification method of the present embodiment, an unused optical fiber is connected from the optical fiber cable 140a connected to the most downstream splitter 130 as an optical fiber to be newly installed (hereinafter referred to as a new optical fiber). It provides a method of identification. In this embodiment, an installation location of a closure (hereinafter referred to as a withdrawal closure) 150 in which the ONU is newly installed is set as a measurement position, and a downstream optical signal and an upstream optical signal transmitted through the optical fiber in the optical fiber cable 140a are measured at this measurement position. The optical fiber core identification device 200 measures and makes a determination to identify the newly installed optical fiber core.

  In the optical fiber identification method of the present embodiment, an unused optical fiber is connected from the optical fiber cable 140a connected to the most downstream splitter 130 as an optical fiber to be newly installed (hereinafter referred to as a new optical fiber). It provides a method of identification. In this embodiment, an installation location of a closure (hereinafter referred to as a withdrawal closure) 150 in which the ONU is newly installed is set as a measurement position, and a downstream optical signal and an upstream optical signal transmitted through the optical fiber in the optical fiber cable 140a are measured at this measurement position. The optical fiber core identification device 200 measures and makes a determination to identify the newly installed optical fiber core.

  In the present embodiment, identification of the newly installed core wire is performed in two stages. That is, in the first stage, an unused core wire (hereinafter referred to as a temporary newly installed core wire) that is considered to be capable of newly establishing an ONU is identified, and in the second stage, the temporary core identified in the first stage is identified. It is confirmed that the newly installed core wire is certainly unused and the newly installed ONU can be newly installed. FIG. 2A shows a first-stage optical core identification method, and FIG. 2B shows a second-stage optical core identification method.

  First, in the first stage, an optical signal having a wavelength λ1 transmitted from the OLT 111 is used as a downstream optical signal to be measured that is measured by the optical fiber identification device 200 of the present embodiment. When the core wire to be measured is connected to the splitter 130, the optical fiber core identification device 200 detects the downstream optical signal, and the core wire to be measured is not connected to the splitter 130. In this case, the downstream optical signal is not detected by the optical fiber identification device 200. Therefore, it is possible to determine whether or not the core wire to be measured is connected to the splitter 130 by using the optical signal having the wavelength λ1 transmitted from the OLT 111 as the downstream optical signal.

  In addition, as the upstream optical signal to be measured, an optical signal having a wavelength λ2 transmitted from the ONU 120 is used. When the core wire to be measured is an active core wire in which the ONU 120 has already been installed, an upstream optical signal is detected by the optical core wire identification device 200, and the core wire to be measured is an unused core wire. In this case, the upstream optical signal is not detected by the optical fiber identification device 200. Therefore, by using the optical signal having the wavelength λ2 transmitted from the ONU 120 as the upstream optical signal, it is possible to determine whether the core wire to be measured is the active core wire or the unused core wire.

  Therefore, in the first stage of the optical fiber identification method of the present embodiment, the optical fiber identification device 200 detects the downstream optical signal with the wavelength λ1 transmitted from the OLT 111 and the upstream optical signal with the wavelength λ2 transmitted from the ONU 120. When no signal is detected, it is determined that the core wire to be measured is a newly-installable core wire of the ONU and a temporary newly-installed core wire expected. Here, the reason why the provisional core wire is determined not to be a new target core wire is as follows.

  In the optical core identification method in the first stage, an optical signal having a wavelength λ2 transmitted from the ONU 120 is used as an upstream optical signal, and the upstream optical signal is not detected by the optical core identification device 200. However, even if the ONU 120 is installed, the optical signal with the wavelength λ2 is not transmitted, for example, when the power is turned off. For this reason, when the power of the ONU 120 is turned off, the working core wire to which the ONU 120 is connected is erroneously identified as an unused core wire.

  Therefore, in the optical core identification method of the present embodiment, in the second stage, whether or not the temporary new target core identified in the first stage is an unused core where the ONU 120 is not installed. I have confirmed. In the optical fiber identification method of the second stage, first, the temporary new object core wire identified in the first stage is drawn down and cut by the closure unit 150, and the downstream of the cut temporary new object core wire is cut. Test light of wavelength λ3 is incident from the end. When the ONU 120 is installed on the downstream side of the provisional target core wire, the test light is reflected by the termination 121 provided in the ONU 120, and this is detected as an upstream optical signal by the optical core identification device 200. .

  Therefore, after the test light having the wavelength λ3 is incident, the optical fiber identification device 200 measures the upstream optical signal, and when the upstream optical signal reflecting the test light is detected, the provisional newly installed core Is determined to be an active core, not a new core. If no upstream optical signal is detected by the optical core identification device 200, the optical core identification device 200 determines that the ONU 120 is not installed downstream of the temporary new target core, and determines that the temporary new target is not installed. The core wire is identified as the target core wire.

  The optical fiber identification method of the present embodiment will be described in further detail using the flowchart shown in FIG. First, as a first stage, in step S1, it is confirmed that the downstream optical signal having the wavelength λ1 is being transmitted from the OLT 111 and the upstream optical signal having the wavelength λ2 is being transmitted from the ONU 120. The downstream optical signal and upstream optical signal are measured at the measurement position where the drop closure 150 is installed (step S2). In step S3, it is first determined whether or not a downstream optical signal has been detected.

  If it is determined in step S3 that a downstream optical signal is detected, it is confirmed that the core wire to be measured is connected to the splitter 130, and the process proceeds to step S4. On the other hand, when the downstream optical signal is not detected, it is determined that the core wire to be measured is not connected to the splitter 130, and it is identified that the core wire is not to be newly installed (step S5).

  In step S4, it is determined whether or not an upstream optical signal is detected. If no upstream optical signal is detected, the measurement target core is identified as a temporary new target core (step S6). When an upstream optical signal is detected, it is determined that the ONU 120 is connected to the downstream side of the measurement target core wire, and the measurement target core wire is identified as not being a new target core wire. (Step S7).

  When a temporary new core wire is identified in step S6, the process proceeds to step S11 as a second stage. In step S11, first, the temporary new core wire is cut. In step S12, the test light having the wavelength λ3 is incident on the downstream core of the cut temporary new target core. Further, in step S13, the upstream optical signal is measured. The upstream optical signal measured here is obtained by reflecting the test light incident in step S12 on the termination 121 when the ONU 120 is installed on the downstream side of the temporary installation target core wire.

  In step S14, it is determined whether or not an upstream optical signal is detected. If no upstream optical signal is detected, the measurement target core is identified as a new target core (step S15). When an upstream optical signal is detected, it is determined that the ONU 120 is connected to the downstream side of the measurement target core wire, and the measurement target core wire is identified as not being a new target core wire. (Step S16).

  FIG. 3 shows the configuration of optical fiber identification device 200 according to the embodiment of the present invention. The optical fiber identification device 200 includes a first detector 211 that detects a downstream optical signal transmitted from the OLT 111 in the downstream direction, and a second detector 212 that detects an upstream optical signal transmitted in the upstream direction. The detection unit 210 provided, the determination processing unit 220 for inputting the respective measured values from the first detector 211 and the second detector 212 and identifying the newly installed core, and the test light having the wavelength λ3 is emitted. And a light source 230.

  The first detector 211 has a wavelength selection function so as to measure only the optical signal having the wavelength λ1 to be measured. For example, an optical that allows only the optical signal having the wavelength λ1 to pass through the front surface of the photodiode (PD). A filter can be provided. The second detector 212 measures the upstream optical signal transmitted from the ONU 120 having the wavelength λ2 in the first stage, and measures the test light having the wavelength λ3 as the upstream optical signal in the second stage. Therefore, the second detector 212 is provided with a wavelength selection function for measuring only the optical signal having the wavelength λ2 in the first stage and measuring only the optical signal having the wavelength λ3 in the second stage. Furthermore, since the detector 212 needs to measure the test light reflected by the termination 121, a sensor having a highly sensitive performance is used.

  The determination processing unit 220 inputs measurement values measured by the first detector 211 and the second detector 212, and executes the processing shown in FIG. The light source 230 is used as a light source for the test light incident in step S12 of the second stage. In the present embodiment, the light source 230 is controlled from the determination processing unit 220.

  As described above, according to the optical fiber identification method and optical fiber identification device of the present invention, in the first stage, the downstream optical signal transmitted from the OLT and the upstream optical signal transmitted from the ONU are detected. Thus, the new target core wire is identified, and the new target core wire is identified using the test light in the second stage. Is possible. In addition, it is possible to save labor since it is only necessary to withdraw work personnel and arrange them only at the installation place of the closure.

  As the optical fiber identification method of another embodiment of the present invention, it is possible to use only the optical fiber identification method of the first stage according to the first embodiment. That is, the provisional new core wire identified in step S6 of FIG. 1 is determined as the new target core wire. Accordingly, in the present embodiment, the processing in the second stage of FIG. 1 is not required, and therefore the light source 230 for emitting the test light having the wavelength λ3 is not required, and the cost can be reduced.

  An optical fiber identification method according to still another embodiment of the present invention will be described below with reference to FIG. In the optical core identification method of the present embodiment, the test light emitting means 112 for emitting the test light having the wavelength λ3 is provided in the station 110, and the test light emitted by the test light emitting means 112 can be transmitted from the station 110 in the downstream direction. I am doing so. Further, an optical switch 113 is provided for selecting one of the optical signal having the wavelength λ1 transmitted from the OLT 111 and the test light having the wavelength λ3 emitted from the test light emitting unit 112.

  When a new target core wire is identified by the optical fiber core identification method of the present embodiment, the optical switch 113 is switched to the test light emission means 112 side, the test light emission means 112 emits test light, and is sent downstream. . In this embodiment, an optical signal having a wavelength λ1 transmitted from the OLT 111 is used as a downstream optical signal as an optical signal measured from the measurement target core wire, and the test light having a wavelength λ3 is reflected by the termination 121 as the upstream optical signal. Thus, an optical signal transmitted in the upstream direction is used.

  Similarly to the first embodiment, whether or not the core wire to be measured is connected to the splitter 130 is determined from the detection of the downstream optical signal. Further, from the upstream signal, it is determined whether or not the core wire to be measured is the active core wire. The determination process of the uplink signal that is the test light is the same as the process from step S13 to step S16 that is the process of the second stage of the first embodiment shown in FIG.

  As described above, according to the optical fiber identification method of the present embodiment, the test light emission means 112 that emits the test light is provided in the station 110. Therefore, the optical fiber identification device 200 shown in FIG. This eliminates the necessity of providing the light source 230, and enables the optical core identification device to be reduced in size and cost.

  An optical fiber identification method and an optical fiber identification device according to still another embodiment of the present invention will be described with reference to FIG. FIG. 7 is an overall flowchart for explaining the optical fiber core identification method of the present embodiment for identifying a target fiber core capable of newly establishing an ONU using the optical fiber core identification device 300 of the present embodiment. In the method of performing the optical fiber identification using the optical optical fiber identification device 200 described above, it is necessary to provide the optical optical fiber identification device 200 or the station 110 with test light emitting means for emitting the test light having the wavelength λ3. Will take.

  Therefore, in this embodiment, instead of measuring the reflected light reflected by the termination 121 of the test light, the reflected light of wavelength λ1 whose downstream optical signal is reflected by another reflecting means at the end of the core wire is targeted. A change in the intensity of the reflected light of wavelength λ1 when the transmission loss of the core wire is changed is detected. That is, when a transmission loss is added to the core wire downstream from the measurement position and the change in the optical signal due to this is detected by the second detector, the reflected light having the wavelength λ1 in the upstream direction is transmitted. Can be determined. In this case, it is necessary to confirm in advance that the optical signal having the wavelength λ2 is not transmitted from the ONU 120 in the upstream direction.

  In the optical fiber identification method of this embodiment, as shown in FIG. 7, the measurement of the optical signal is performed in two stages, and the optical signal of wavelength λ2 is measured in the first stage indicated by reference numeral 301. The measurement of the optical signal with the wavelength λ2 is performed by blocking the optical signal with the wavelength λ1 so that the optical signal with the wavelength λ1 is not measured. If an optical signal having the wavelength λ2 is detected as a result of the measurement in the first stage 301, it is determined that the core wire to be measured is the active core wire to which the ONU is connected. If no optical signal having the wavelength λ 2 is detected, a second-stage measurement indicated by reference numeral 302 is performed.

  In the measurement of the second stage 302, the reflected light of the optical signal having the wavelength λ1 transmitted from the OLT 111 is measured. However, since the intensity of the reflected light is low, this may not be detected. Therefore, in this embodiment, a predetermined loss is added to the core wire being measured on the downstream side from the measurement position, thereby changing the measurement value. It is detected whether or not. As a result, when a change in the measured value is detected, it can be determined that the reflected light having the wavelength λ1 is transmitted in the upward direction, and the core can be determined as the newly installed core. The loss added to the core wire may be about 1 to 2 dB, and by adding such a loss, it is possible to determine the change in the reflected light of wavelength λ1.

  Since it has been confirmed that the optical signal having the wavelength λ2 has not been transmitted from the ONU in the first stage 301, the change in the measured value due to the loss added downstream from the measurement position is the core wire being measured. It can be determined that the light is reflected by the reflected light having the wavelength λ1. In addition, the position where loss is added needs to be downstream from the measurement position. If loss is added upstream from the measurement position, the intensity of the downstream optical signal also changes before and after the loss is added at the measurement position. Therefore, it becomes impossible to detect the presence or absence of a change in the reflected light of wavelength λ1.

  As described above, in the optical fiber identification method of the present embodiment, it is confirmed in the first stage 301 that the optical fiber of wavelength λ2 is not transmitted from the ONU, and in the second stage 302, the optical fiber is detected from the measurement position. By determining that the core wire whose measured value changes when the loss is added on the downstream side is the newly installed core wire, even if the intensity of the reflected light of wavelength λ1 is low, the newly installed core wire can be accurately Judgment is possible.

  A schematic configuration of the optical fiber identification device 300 of the present embodiment is shown in FIG. The optical fiber identification device 300 is detachably provided with filters 313 and 314 for cutting an optical signal having a wavelength λ1 in front of the light receiving surfaces of the detectors 311 and 312. The filters 313 and 314 are used when measuring an optical signal having a first-stage wavelength λ2.

  The first detector 311 detects a downstream optical signal transmitted in the downstream direction from the OLT 111, as in the optical core identification device 200, and the second detector 312 has a wavelength as an upstream optical signal. The reflected light of λ1 or the optical signal of wavelength λ2 transmitted from the ONU 120 is measured. When measuring the optical signal having the wavelength λ2 by the second detector 312, in order to prevent the optical signal having the wavelength λ1 from being received, each of the first detector 311 and the second detector 312 is provided. The filters 313 and 314 are attached. The filters 313 and 314 are filters that block the optical signal having the wavelength λ1.

  The optical fiber identification device 300 according to the present embodiment further includes loss adding means 330 for adding a loss of a predetermined magnitude to the optical fiber to be measured. The loss adding means 330 may be integrally provided in a housing (not shown) of the optical fiber identification device 300 or may be provided separately from the housing of the optical fiber identification device 300.

  The optical core identification method of this embodiment performed using the optical core identification device 300 will be described in more detail with reference to the flowchart of FIG. First, in step S21, filters 313 and 314 are mounted in front of the light receiving surfaces of the detectors 311 and 312, and in the next step S22, an optical signal having a wavelength λ2 is measured to obtain a first measurement value. In step S23, it is determined whether or not the first measurement value is smaller than a predetermined threshold value A1, and if it is smaller than the threshold value A1, the process proceeds to step S25 of the second step. A line is determined (step S24). As the threshold A1, a value suitable for determining the presence / absence of an optical signal having the wavelength λ2 is used.

  In the second stage, first, the filters 313 and 314 are removed from the front side of the light receiving surfaces of the detectors 311 and 312 in step S25. In the next step S26, the detector 312 measures the reflected light having the wavelength λ1, and obtains the second measurement value. After that, a predetermined loss is added downstream from the measurement position of the core wire using the loss adding means 330 (step S27), and the reflected light of the wavelength λ1 at that time is measured by the detector 312 to obtain a third measured value. Is acquired (step S28). In step S29, it is determined whether the absolute value of the difference between the second measurement value and the third measurement value is greater than a predetermined threshold A2.

  As a result of the determination in step S29, when it is determined that the absolute value of the difference between the two is larger than the threshold value A2, it is determined that a change in the reflected wave having the wavelength λ1 has been detected, and the core is determined to be a newly installed core. (Step S30). If the absolute value of the difference between the two is less than or equal to the threshold value A2, it is determined that there is no reflected wave, and the core is determined to be the active core (step S31). The threshold A2 is set to a value suitable for detecting a change in the reflected wave having the wavelength λ1.

  One example using the core identification method of the present embodiment will be described below with reference to FIG. In the core wire identification method according to the present embodiment, it is possible to easily determine whether or not the optical signal having the wavelength λ2 is transmitted from the ONU 120 based on the first measurement value. Therefore, in FIG. 10, a second-stage core identification method will be described. In the second stage, it is confirmed that the light passing through the core wire under measurement is only the optical signal having the wavelength λ1 transmitted from the OLT 111.

  FIGS. 10A and 10B show the intensity of the optical signal having the wavelength λ1 when the ONU 120 is not connected to the end of the core wire being measured. In the example of FIG. 10A, the intensity of the downstream optical signal having the wavelength λ1 at the measurement position is set to −23 dBm, and the reflection by another reflecting means at the end of the core wire has a reduction of 15 dB. In this case, the intensity of the reflected wave at the measurement position is −38 dBm.

  As described above, when there is a reflected wave of wavelength λ1, the detector 312 receives leaked light from the reflected wave of −38 dBm, but the detector 312 also has a small amount of optical signal in the downstream direction of wavelength λ1. There is light reception. Therefore, the measured value of the detector 312 is larger than the leaked light from the reflected wave of −38 dBm. From this measured value, it is difficult to determine the intensity of only the reflected light leakage light.

  Therefore, in the present embodiment, as shown in FIG. 10B, a predetermined loss (−1 dB) is added to the core wire downstream from the measurement position. In this case, the intensity of the downstream optical signal that has passed through the measurement position decreases by 1 dB at the loss addition point and then decreases by 15 dB when reflected by another reflecting means. The reflected wave that travels in the upward direction after being reflected drops again by 1 dB at the loss point, so that the intensity of the reflected wave received by the detector 312 becomes −40 dBm.

As described above, the loss is added by 1 dB by the loss adding means, and the detector 312 measures the change in the leaked light when the intensity of the optical signal is changed by 2 dB. When the intensity at the measurement position without adding loss -38 dBm and the intensity at the measurement position with loss added --40 dBm are converted into linear values, they are 1.58 × 10 ⁻⁴ mW and 1.00 × 10 ⁻ , respectively. ⁴ mW. It is possible to confirm that a reflected wave of wavelength λ1 is transmitted by detecting a change in leakage light when the intensity of the optical signal changes by 0,58 × 10 ⁻⁴ mW which is the difference between the two. it can.

  On the other hand, when the ONU 120 is connected to the end of the optical fiber, as shown in FIG. 10C, when no loss is added, the downstream optical signal is reflected by the ONU 120 with a drop of 50 dB. The As a result, the detector 312 receives light leaked from the optical signal having an intensity of −73 dBm. Further, in the case of FIG. 10D in which loss is added by the loss adding means 330, the leak light from the optical signal having an intensity of −75 dBm is measured by the detector 312.

When converting the intensity of the optical signal without addition of loss -73 dBm and the intensity of the optical signal with addition of loss -75 dBm into linear values, 5.01 × 10 ⁻⁸ mW and 3.16 × 10 ^{− respectively. 8} mW. Therefore, the difference between the two is 1.85 × 10 ⁻⁸ mW, but the change in leakage light due to such a slight change in intensity is extremely small, and it is almost impossible to detect this. Therefore, when the change in the measured value of the detector 312 due to the presence or absence of loss is sufficiently small (smaller than the threshold value A2), it can be determined that the ONU 120 is connected to the core wire.

  In the above, the influence of leakage light from the downstream optical signal with wavelength λ1 was not considered, but when the detector 312 also receives the leakage light of the downstream optical signal with wavelength λ1, The measured value of the detector 312 becomes larger. However, since the downstream optical signal of wavelength λ1 received by the detector 312 does not change depending on whether or not loss is added by the loss adding device, the detector 312 with and without adding loss. The difference in the measured value due to is determined only by the change in the intensity of the reflected light of wavelength λ1. Therefore, it is possible to determine whether or not the reflected light having the wavelength λ1 is transmitted depending on whether or not the change in the measurement value of the detector 312 is detected. It becomes possible to judge.

  In addition, the description in this Embodiment shows an example of the optical fiber identification method and optical fiber identification device which concern on this invention, and is not limited to this. The detailed configuration and detailed operation of the optical fiber identification method and optical fiber identification device in the present embodiment can be appropriately changed without departing from the spirit of the present invention.

It is a flowchart which shows the flow of a process of the core wire identification method which concerns on embodiment of this invention. It is a schematic diagram of the PON communication system for demonstrating the core wire identification method which concerns on embodiment of this invention. It is a block diagram which shows the core wire identification device which concerns on embodiment of this invention. It is a schematic diagram of the PON communication system for demonstrating the core line identification method of another embodiment of this invention. It is a block diagram which shows schematic structure of a PON communication system. It is a schematic diagram of the PON communication system for demonstrating the conventional core wire identification method. It is a whole flowchart explaining the optical fiber identification method which concerns on another embodiment of this invention. It is a block diagram which shows the core wire identification device which concerns on another embodiment of this invention. It is a flowchart which shows the flow of a process of the core wire identification method which concerns on another embodiment of this invention. It is a figure explaining 1 Example using the core wire identification method which concerns on another embodiment of this invention.

Explanation of symbols

100, 900 PON communication system 110 Station 111, 901 OLT
112 Test light emitting means 113 Optical switch 120, 903 ONU
121 Termination 130, 902 Splitter 140, 910 Optical fiber cable 150, 920 Pull-down closure unit 200, 300 Core identification device 210, 310 Detection unit 211, 212, 311, 312 Detector 313, 314 Filter 220, 320 Determination processing unit 330 Loss addition means

Claims (9)

An optical fiber cable that connects an optical line terminal (OLT) that transmits an optical signal of the first wavelength from the station side and an ONU (optical network unit) that transmits an optical signal of the second wavelength on the user side via a splitter. In a PON (Passive Optical Network) communication system configured by connecting with each other, an unused core in which the ONU can be newly installed from a plurality of core wires in the optical fiber cable routed between the splitter and the ONU An optical fiber identification method for identifying a line (hereinafter referred to as a new installation core),
An optical signal of the first wavelength (hereinafter referred to as a downstream optical signal) transmitted from the OLT toward the ONU side (hereinafter referred to as a downstream direction), and from the ONU side toward the OLT side (hereinafter referred to as a downstream optical signal). An optical signal to be transmitted (hereinafter referred to as upstream optical signal) is measured downstream of the splitter,
The optical fiber identification method, wherein the optical fiber when the downstream optical signal is detected and the upstream optical signal is not detected is determined as the newly installed optical fiber. The optical fiber identification method according to claim 1, wherein the upstream optical signal is an optical signal of the second wavelength transmitted from the ONU in the upstream direction. The OLT is provided with a test light emitting means having a third wavelength, and
The ONU is provided with reflecting means for reflecting the test light of the third wavelength,
The test light is transmitted from the OLT by the test light emitting means in the downward direction,
The optical fiber identification method according to claim 1, wherein the test light reflected by the reflecting means and transmitted in the upstream direction is measured as the upstream optical signal. The ONU is provided with reflecting means for reflecting the test light of the third wavelength,
The core wire when the downstream optical signal transmitted from the OLT is detected and the upstream optical signal of the second wavelength transmitted from the ONU is not detected is determined as a temporary new target core wire. Cut and
The test light of the third wavelength is incident from the end in the downward direction where the temporary new core wire is cut,
2. The optical core line determination method according to claim 1, wherein when the test light is not detected as the upstream optical signal, the temporary new core wire is determined as the new target core wire. 3. Another reflecting means for reflecting the downstream optical signal is provided in advance on the other end of the core wire opposite to the one end connected to the splitter,
Measuring the upstream optical signal passing through the core at a predetermined measurement position downstream of the splitter to obtain a first measurement value;
When the first measurement value is smaller than a predetermined threshold value,
Measuring the reflected light that the downstream light signal is reflected by the other reflecting means and transmitted in the upstream direction at the measurement position to obtain a second measured value;
Measuring the reflected light when giving a predetermined loss to the core wire downstream from the measurement position to obtain a third measurement value;
The optical core identification method according to claim 1, wherein when the second measurement value and the third measurement value are different, the core wire is determined as the newly-installed target core wire. A PON communication system configured by connecting an OLT that transmits an optical signal having a first wavelength from the station side and an ONU that transmits an optical signal having a second wavelength on the user side via an optical fiber cable via a splitter. An optical core that identifies an unused core (hereinafter referred to as a new core to be installed) from which the ONU can be newly installed from a plurality of cores in the optical fiber cable routed between the splitter and the ONU A line identification device,
A first signal is provided on the downstream side of the splitter, and detects an optical signal of the first wavelength (hereinafter referred to as a downstream optical signal) transmitted from the OLT toward the ONU side (hereinafter referred to as a downstream direction). A detector having a detector and a second detector for detecting an optical signal (hereinafter referred to as upstream optical signal) transmitted from the ONU side toward the OLT side (hereinafter referred to as upstream direction);
Each measurement value is input from the first detector and the second detector of the detection unit, the downstream optical signal is detected by the first detector, and the second detector And a determination processing unit that determines the core wire when the upstream optical signal is not detected as the newly-installed core wire. The optical fiber identification device according to claim 6, further comprising test light emitting means for emitting test light having a third wavelength. The light according to claim 6, wherein each of the first detector and the second detector has a wavelength selection function of selectively receiving the downstream optical signal and the upstream optical signal. Core wire identification device. Furthermore, a loss adding means for adding a loss of a predetermined magnitude to the core wire is provided,
The first detector and the second detector are detachably attached with a filter for blocking the reflected light reflected by another reflecting means provided at the end of the core wire for the downstream signal and the downstream signal. Each provided as possible,
The determination processing unit includes a first measurement value obtained by mounting the filter on the first detector and the second detector and measuring the upstream optical signal with the second detector; A second measurement value obtained by removing the filter from the detector and the second detector and measuring the reflected light by the second detector; and from the first detector and the second detector. A third measured value obtained by removing the filter and adding the loss by the loss adding means, and inputting the third measured value, wherein the first measured value is smaller than a predetermined threshold value and the second measured value. The optical core identification device according to claim 6, wherein the core wire determined to be different from the third measurement value is determined as the newly-installed core wire.

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