JP2008107106A - Optical path testing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical path testing system capable of specifying which far-end-side optical communication device reflected pulses are from optical pulse reflecting means for test corresponding to without requiring operators to determine or actually measure the distances between a near-end-side optical communication device such as OLT and far-end-side optical communication devices such as ONUs on the basis of their design drawing. <P>SOLUTION: The optical path testing system 100 includes a test acceptance determining means 70. The test acceptance determining means 70 determines the difference between a reflection level when the M-th far-end-side optical communication device 30 is connected to a second optical path 24 and a reflection level when the (M-1)-th far-end-side optical communication device 30 is connected to the second optical path 24 and correlates reflecting locations in such a way that the distance to a reflecting location at which the reflection level is the highest among the reflection level differences may be correlated to the M-th far-end-side optical communication device 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical line test system for measuring optical loss of an optical fiber by using an optical pulse measuring device (Optical Time Domain Reflectometer).

  A technique is disclosed in which a reflection level from a reflector attached immediately before an ONU (Optical Network Unit) is measured, and an optical loss of an optical fiber of an optical fiber communication network is obtained by an optical pulse measuring device (for example, a patent) See reference 1.)

  In addition, a technique for measuring a change in a reflection level and a reflection position from a reflector attached immediately before an ONU with an optical pulse measuring device and isolating a failure occurring in an optical fiber communication network is disclosed (for example, (See Patent Document 2).

JP 2003-222573 A JP-A-4-211204

  When a plurality of ONUs are connected to an optical fiber communication network, the technique disclosed in Patent Document 1 or 2 measures a plurality of reflected pulses from a plurality of ONUs by emitting one test optical pulse. Therefore, it is necessary to identify which reflected pulse corresponds to which ONU in advance. Here, if the correspondence between the reflected pulse and the ONU is not specified in advance, even if the reflected level of the reflected pulse fluctuates, it is difficult to determine which ONU has failed. there were.

  By determining the distance from the optical line terminal (OLT) to the ONU from the design drawing, it is possible to specify the correspondence between the reflected pulse and the ONU. However, in the method in which the operator obtains the distance from the OLT to the ONU from the design drawing, there is a connection error of the optical fiber in the closure or the cabinet in addition to the design error of the design drawing, and an error may occur. Due to this error, when the distance from the OLT to the plurality of ONUs is short, there is a problem that the correspondence between the reflected pulse and the ONU cannot be specified accurately.

  In addition, there is a method in which the operator measures the length of the optical fiber connecting the OLT and the ONU with a measuring means such as a measure during construction or inspection, and obtains the distance from the OLT to the ONU. However, it is very difficult for the operator to actually measure the length of the optical fiber, and when the optical fiber is laid inside the pipe, it is very difficult to measure the length of the optical fiber. was there.

  In order to solve the above-described problem, the present invention can determine which distance from a near-end optical communication device such as an OLT to a far-end optical communication device such as an ONU without obtaining or actually measuring the distance from the design drawing. It is an object of the present invention to provide an optical line test system capable of specifying whether a reflected pulse from a test optical pulse reflecting means corresponding to a far-end optical communication device. Another object of the present invention is to provide an optical line test system capable of determining optical loss and determining whether the optical line is faulty or the far-end optical communication apparatus is faulty.

  In order to achieve the above object, an optical line test system according to the present invention includes a reflection level when an Mth far-end optical communication device is connected to a second optical line, and an M-1st far-end. The difference from the reflection level when the side optical communication device is connected to the second optical line is obtained, and the distance to the reflection position having the highest reflection level among the differences is determined to the Mth far-end optical communication device. Test pass / fail judgment means for associating corresponding reflection positions is provided.

  Specifically, the optical line testing system according to the present invention includes a near-end optical communication device, N (where N is a positive integer) far-end optical communication devices communicating with the near-end optical communication device, An optical branch circuit that branches to N or more, a first optical line that connects the near-end optical communication device and the optical branch circuit, and the optical branch circuit and the N far-end optical communication devices are connected to each other. Light having N second optical lines, and a test light pulse reflecting means that is inserted between the N far-end optical communication devices and the second optical line and reflects the test light pulse. An optical line test system for testing a network, which is connected to the first optical line via a coupling circuit, emits the test optical pulse toward the far-end optical communication device, and is a distance to a reflection position An optical pulse measuring instrument for measuring the reflection level with respect to the optical pulse measuring instrument An optical loss between the coupling circuit and the test optical pulse reflecting means is obtained from a reflection level with respect to a distance to a reflection position measured by the optical pulse measuring device by emitting a test optical pulse, and based on the optical loss. Test pass / fail judgment means for judging pass / fail of the test, wherein the test pass / fail judgment means is configured such that the Mth (where M is a positive integer less than or equal to N) the far-end optical communication device is the second light beam. The reflection level with respect to the distance to the reflection position when connected to the road and the reflection with respect to the distance to the reflection position when the M−1th far-end optical communication device is connected to the second optical line. A difference with a level is obtained, and a reflection position is associated with which the distance to the reflection position having the highest reflection level among the differences is associated with the M-th far-end optical communication device. To do.

  The difference corresponds only to the Mth far-end optical communication apparatus. Thereby, the distance to the M-th far-end optical communication device can be obtained from the difference. Therefore, the optical line test system described above performs the actual measurement without associating the distance from the near-end side optical communication apparatus to the far-end side optical communication apparatus from the design drawing by associating the reflection positions. Without this, it is possible to identify which far-end optical communication device corresponds to the reflected pulse from the test optical pulse reflecting means. Furthermore, the optical line test system described above can determine whether an optical loss or a far-end side optical communication apparatus has a failure while obtaining an optical loss.

  To achieve the above object, an optical line test system according to the present invention includes a test optical pulse reflecting means for reflecting a test optical pulse, and an M-th far-end optical communication device as a second optical line. The difference between the reflection level when connected and the reflection level when the M−1th far-end optical communication device is connected to the second optical line is obtained, and the reflection becomes the highest reflection level among the differences. Test pass / fail judgment means for associating a reflection position with which the distance to the position is associated with the Mth far-end optical communication device is provided.

  Specifically, the optical line testing system according to the present invention includes a near-end optical communication device, N (where N is a positive integer) far-end optical communication devices communicating with the near-end optical communication device, An optical branch circuit that branches to N or more, a first optical line that connects the near-end optical communication device and the optical branch circuit, and an optical branch circuit and the N far-end optical communication devices, respectively. An optical line test system for testing an optical network having N second optical lines to be connected, which is inserted between the N far-end optical communication devices and the second optical line, A test light pulse reflecting means for reflecting the light pulse; and connected to the first optical line via a coupling circuit; emitting the test light pulse toward the far-end optical communication device; An optical pulse measuring instrument for measuring the reflection level with respect to the distance; A light loss between the coupling circuit and the test light pulse reflecting means is obtained from a reflection level with respect to a distance to a reflection position measured by the light pulse measuring device by emitting a test light pulse, and based on the light loss. Test pass / fail judgment means for judging pass / fail of the test, wherein the test pass / fail judgment means is configured such that the Mth (where M is a positive integer less than or equal to N) the far-end optical communication device is the second light beam. The reflection level with respect to the distance to the reflection position when connected to the road and the reflection with respect to the distance to the reflection position when the M−1th far-end optical communication device is connected to the second optical line. A difference with a level is obtained, and a reflection position is associated with which the distance to the reflection position having the highest reflection level among the differences is associated with the M-th far-end optical communication device. To do.

  The difference corresponds only to the Mth far-end optical communication apparatus. Thereby, the distance to the M-th far-end optical communication device can be obtained from the difference. Therefore, the optical line test system described above performs the actual measurement without associating the distance from the near-end side optical communication apparatus to the far-end side optical communication apparatus from the design drawing by associating the reflection positions. Without this, it is possible to identify which far-end optical communication device corresponds to the reflected pulse from the test optical pulse reflecting means. Furthermore, the optical line test system described above can determine whether an optical loss or a far-end side optical communication apparatus has a failure while obtaining an optical loss.

  In the optical line test system according to the present invention, the optical network is established when a link is established between the near-end side optical communication device and the M-th far-end side optical communication device. The near-end optical communication device transmits link information indicating that the reflection position has been received, and the test acceptance / rejection determination unit receives the link information from the near-end optical communication device. It is preferable to perform association.

  In the above optical line test system, the far-end side optical communication device is further connected to the second optical line before the reflection position is associated, so that the reflection position is associated. The situation that cannot be reduced can be reduced.

  In the optical line test system according to the present invention, the test pass / fail judgment means obtains a noise level at which the reflection level is highest due to noise generated inside the optical pulse measuring device, and the reflection position is based on the noise level. Is preferably performed.

  The above optical line test system can accurately associate the reflection positions without being affected by the noise.

  In the optical line test system according to the present invention, the test pass / fail determination means obtains the backscattered light level at which the reflection level of the backscattered light with respect to the distance to the reflection position measured by the optical pulse measuring device is the highest, It is preferable to associate the reflection positions with reference to the backscattered light level.

  The above optical line test system can accurately associate the reflection positions without being affected by the backscattered light.

  In the optical line test system according to the present invention, the optical network includes an optical connector disposed between the optical pulse measuring instrument and the far-end optical communication device, and the test pass / fail judgment means is generated at the optical connector. Preferably, the optical connector reflection level at which the reflection level is the highest is obtained, and when the optical connector reflection level is higher than the backscattered light level, the reflection position is associated with the optical connector reflection level as a reference. .

  The optical line test system described above can be more accurately associated with the reflection position without being affected by the reflection level generated in the optical connector.

  In the optical line testing system according to the present invention, it is preferable that the optical fiber testing system further includes a communication terminal that displays the pass / fail of the test, and the test pass / fail determination means wirelessly notifies the communication terminal of the pass / fail of the test.

  The optical line test system described above is convenient because the operator who has the communication terminal can know whether the test has passed, regardless of where the operator is.

  In the optical line testing system according to the present invention, the optical network transfers a warning indicating that the near-end optical communication device passes the test to the far-end optical communication device, and the far-end optical communication device It is preferable that the content of the warning is output according to the warning, and the test pass / fail determination means transmits the warning to the near-end side optical communication device and forwards the warning to the far-end side optical communication device.

  The above optical line test system is convenient because it can notify the operator near the far-end optical communication device of the success or failure of the test.

  The present invention relates to which far-end optical communication device an operator does not obtain or actually measure the distance from a near-end optical communication device such as an OLT to a far-end optical communication device such as an ONU from a design drawing. It is possible to provide an optical line test system capable of specifying whether the reflected pulse is from the corresponding test optical pulse reflecting means. Furthermore, the present invention can provide an optical line test system that can determine whether the optical loss is a failure or the far-end optical communication device is a failure while determining the optical loss.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiment described below is an example of the configuration of the present invention, and the present invention is not limited to the following embodiment. Moreover, the same code | symbol was attached | subjected to the same member and the same site | part.

(First embodiment)
FIG. 1 shows a schematic configuration diagram of an optical line test system according to the first embodiment. The optical line test system according to the first embodiment includes a near-end optical communication device 10, eight far-end optical communication devices 30 that communicate with the near-end optical communication device 10, and an optical branch circuit 22 that branches into eight or more. The first optical line 20 that connects the near-end side optical communication device 10 and the optical branch circuit 22, and the eight second optical lines that connect the optical branch circuit 22 and the eight far-end side optical communication devices 30, respectively. 24 and a light beam for testing an optical network, which is inserted between the eight far-end optical communication devices 30 and the second optical line 24 and has a test light pulse reflecting means 60 for reflecting the test light pulse. The road test system 100 is connected to the first optical line 20 via a coupling circuit 52, emits a test optical pulse toward the far-end optical communication device 30, and sets the reflection level with respect to the distance to the reflection position. Optical pulse measuring instrument 50 to measure and optical pulse measuring instrument 5 The optical loss between the coupling circuit 52 and the test optical pulse reflecting means 60 is obtained from the reflection level with respect to the distance to the reflection position measured by the optical pulse measuring device by emitting the test optical pulse, and based on the optical loss. A test pass / fail judgment means 70 for judging pass / fail of the test, and the test pass / fail judgment means 70 is configured such that the M-th (where M is a positive integer of 8 or less) far-end optical communication device 30 is the second optical line. The reflection level with respect to the distance to the reflection position when connected to 24 and the reflection level with respect to the distance to the reflection position when the M−1th far-end optical communication device 30 is connected to the second optical line 24 Is obtained, and the reflection position is associated with the Mth far-end optical communication device 30 with the distance to the reflection position having the highest reflection level in the difference. Further, FIG. 1 shows an optical switch 54. In FIG. 1, the third to seventh far-end optical communication devices and the second optical line are omitted.

  An example of the near-end optical communication device 10 is an OLT. The first optical line 20 includes a single-core optical fiber having a single core wire. Moreover, as the optical branch circuit 22, there is an optical splitter, for example.

  An example of the second optical line 24 is an optical fiber. Here, the second optical line 24 is, for example, a lead-in section (drop section) from the optical branch circuit 22. Further, as the far-end optical communication device 30, for example, there is an ONU. Further, the test light pulse reflecting means 60 includes, for example, an optical filter that reflects the test light pulse and transmits the signal light. FIG. 2 shows a form in which the test optical pulse reflecting means 60 is inserted between the far-end side optical communication device 30 and the second optical line 24. In the optical line test system 100 of FIG. 1, the test light pulse reflecting means 60 is arranged outside the far-end optical communication device 30 as shown in FIG. Here, as shown in FIG. 2B, the test light pulse reflecting means 60 is preferably arranged inside the far-end optical communication device 30. As a result, when the far-end optical communication device 30 is connected to the second optical line 24, it is possible to quickly perform the test without requiring the time for installing the test optical pulse reflecting means 60.

  The coupling circuit 52 in FIG. 1 is connected to an optical switch 54 that selects the core of the optical fiber to be tested. Although not shown in FIG. 1, the optical switch 54 is connected to a plurality of coupling circuits, for example. The optical pulse measuring instrument 50 is connected to the optical switch 54 via an optical fiber, for example. The test pass / fail determination means 70 is connected to, for example, the near-end optical communication device 10, the optical pulse measuring device 50, and the optical switch 54.

  FIG. 3 shows a block diagram of the test pass / fail judgment means in the first embodiment. The test pass / fail determination means 70 includes, for example, a CPU 71, an OLT interface 72, an optical switch interface 73, an optical pulse measuring instrument interface 74, and a storage unit 75. For example, the CPU 71 performs calculations necessary for controlling the OLT interface 72, the optical switch interface 73, the optical pulse measuring instrument interface 74, and the storage unit 75, and determining whether or not the test has passed. The OLT interface 72 is a terminal for connecting to a near-end side optical communication device such as an OLT via an electrical connection means such as an electric cable. The optical switch interface 73 is, for example, a terminal for connecting to the optical switch via an electrical connection means. The optical pulse measuring instrument interface 74 is a terminal for connecting to the optical pulse measuring instrument via, for example, an electrical connection means. As a result, the test pass / fail judgment means 70 in FIG. 1 receives the signal from the near-end optical communication device 10 and can control the optical pulse measuring instrument 50 and the optical switch 54.

  3 includes, for example, an ONU storage unit 75a, a measurement condition storage unit 75b, a measurement result storage unit 75c, a noise level storage unit 75d, a backscattered light level storage unit 75e, and an optical connector reflection level storage unit 75f. . The ONU storage unit 75a stores the number of far-end side optical communication devices such as ONUs connected to the second optical line 24, for example. The measurement condition storage unit 75b stores, for example, measurement conditions such as the output level of the test optical pulse, the wavelength and pulse width, the measurement distance range, the sampling rate, the number of times of averaging, and the standard values that serve as criteria for pass / fail of the test. By reading the measurement conditions stored in the measurement condition storage unit 75b, tests under the same measurement conditions can be performed. The measurement result storage unit 75c includes, for example, the reflection level measured by the optical pulse measuring instrument, the distance to the reflection position measured by the optical pulse measuring instrument, the reflected waveform measured by the optical pulse measuring instrument, and the test pass / fail judgment means 70. The association of reflection positions to be performed is stored. The noise level storage unit 75d stores a noise level, for example. The backscattered light level storage unit 75e stores, for example, a backscattered light level. The optical connector reflection level storage unit 75f stores, for example, an optical connector reflection level. Details of the noise level, the backscattered light level, and the optical connector reflection level will be described later.

  The portion surrounded by the one-dot chain line in FIG. 1, that is, the procedure for connecting the far-end optical communication device 30 as an example of connecting the second far-end optical communication device 30a to the second optical line 24a. Will be described. FIG. 4 shows a flowchart of the operation of connecting the far-end side optical communication device to the optical branching means. First, the worker carries out wiring work for the second optical line 24a in FIG. 1 (see S101 in FIG. 4). Next, the operator attaches the test light pulse reflecting means 60a to the end of the second optical line 24a (see S102 in FIG. 4). The operator connects the end of the second optical line 24a to which the test optical pulse reflecting means 60a is attached to the far-end optical communication device 30a, and turns on the far-end optical communication device 30a (see FIG. 4). (See S103). The worker starts a link between the far-end side optical communication device 30a and the near-end side optical communication device 10. At this time, it is preferable to set the near-end optical communication device 10 in advance so that a link can be established when the far-end optical communication device 30a is connected. In the optical line test system according to the first embodiment, the optical network is configured when a link is established between the near-end optical communication device 10 and the second far-end optical communication device 30 (see FIG. 4). (See S104.), The near-end optical communication device 10 transmits link information indicating that the link has been established to the test pass / fail judgment means 70 (see S105 in FIG. 4). After the information is received from the near-end optical communication device 10, it is preferable to immediately associate the reflection positions (see S106 in FIG. 4). Thereby, in the optical line testing system according to the first embodiment, after the far-end optical communication device 30a is connected, the far-end optical communication device 30 is further connected to the second optical line 24 before the reflection position is associated. As a result, the situation where the reflection positions cannot be associated can be reduced. Details of the reflection position association will be described later. At this time, it may be necessary to adjust the connection schedule of the far-end optical communication devices 30 so that two or more far-end optical communication devices 30 are not connected to the second optical line 24 at the same time. FIG. 4 is an example of a procedure for connecting the far-end optical communication device, and is not limited to the procedure shown in FIG.

  The operation of the test pass / fail judgment means will be described. FIG. 5 shows a flowchart of the processing of the test pass / fail judgment means. First, the test pass / fail determination means causes the optical switch to select the core wire to be tested (see S201 in FIG. 5). Next, the test pass / fail determination means determines whether or not the first far-end optical communication device is connected (see S202 of FIG. 5). Here, the number of far-end optical communication devices already connected to the second optical line is read from the ONU storage unit 75a in FIG. 3, or the operator registers in advance in the test pass / fail determination means, or the equipment Obtained from a database (not shown in FIGS. 1 and 3). As shown in FIG. 5, the test pass / fail determination means includes the case where the first far-end optical communication device is connected to the second optical line and the second and subsequent far-end optical communication devices are the second optical line. The operation is different depending on the connection. First, the operation of the test pass / fail determination means when the first far-end optical communication device is connected to the second optical line will be described.

  The test acceptance / rejection determination unit sets measurement conditions and stores the set measurement conditions (see S203 in FIG. 5). Under the set measurement conditions, the test pass / fail determination means causes the optical pulse measuring device to emit a test optical pulse and stores the reflection level measured by the optical pulse measuring device (see S204 in FIG. 5). The test acceptance / rejection determination unit associates the reflection position based on the reflection level, and stores the association of the reflection position (see S205 in FIG. 5). FIG. 6 shows a reflected waveform when the first far-end optical communication device is connected to the second optical line. At this time, the test acceptance / rejection determination unit associates the reflection position with which the distance b to the reflection position having the highest reflection level a in the reflection pulse α corresponds to the first far-end optical communication device. Is preferred. This is because only one test optical pulse reflecting means is attached to the optical network, and the reflected pulse α corresponding to the first far-end optical communication device is measured. The test pass / fail determination means calculates the optical loss from the reflection level with respect to the distance to the reflection position, and determines the pass / fail of the test by comparing the optical loss with a predetermined specified value (see S206 in FIG. 5). .

  Next, the operation of the test pass / fail determination means when the second far-end optical communication device is connected to the second optical line will be described. S201 and S202 in FIG. 5 are the same as described above. The test pass / fail judgment means reads the stored measurement conditions (see S207 in FIG. 5). Under the read measurement conditions, the test pass / fail judgment means causes the optical pulse measuring device to emit a test optical pulse and stores the reflection level measured by the optical pulse measuring device (see S208 in FIG. 5). The test acceptance / rejection determination unit associates the reflection positions based on the difference, and stores the association of the reflection positions (see S209 in FIG. 5). FIG. 7 shows a reflected waveform when the second far-end optical communication device is connected to the second optical line. Since two optical pulse reflection means for testing are attached to the optical network, the reflection pulses α and β corresponding to the two far-end optical communication devices are measured as shown in FIG. Here, the reflection level when the first far-end optical communication device is connected to the second optical line and the reflection level when the second far-end optical communication device is connected to the second optical line. Find the difference between FIG. 8 shows a differential waveform between the reflected waveform of FIG. 6 and the reflected waveform of FIG. The test acceptance / rejection determination unit associates the distance d to the reflection position having the highest reflection level c among the differences as a reflection position that corresponds to the second far-end optical communication device. That is, in FIG. 7, the reflected pulse β at the distance d is associated as the second far-end optical communication device. The test pass / fail determination means calculates the optical loss from the reflection pulse β and the distance d to the reflection position, and compares the optical loss with a predetermined value to determine pass / fail of the test (see S206 in FIG. 5). .) Therefore, the optical line test system according to the first embodiment allows the operator to obtain the distance from the near-end side optical communication device to the far-end side optical communication device by associating the reflection positions or from the design drawing. Without actually measuring, it is possible to specify which far-end side optical communication device corresponds to the reflected pulse from the test optical pulse reflecting means.

  Further, when the third far-end optical communication device is connected to the second optical line, the test pass / fail determination means is when the second far-end optical communication device is connected to the second optical line. The reflection position is associated based on the difference between the reflection level of the third optical communication device and the reflection level when the third far-end optical communication device is connected to the second optical line.

  Further, the flowchart of FIG. 5 is a process when the far-end optical communication device is connected. Here, when a failure occurs, by comparing the reflection level stored in the test pass / fail judgment means in advance with the measurement result of the reflection level measured at the time of the failure, which far-end optical communication device is in contact with It is possible to specify whether or not a failure has occurred. Furthermore, the optical line test system according to the first embodiment obtains optical loss, and if the reflected light from the test optical pulse reflection means is not measured, it is determined that the optical line has failed, or from the test optical pulse reflection means. If the reflected light is measured, it is possible to identify a failure as a failure of the far-end optical communication device. FIG. 5 is an example of the operation of the test pass / fail judgment means, and is not limited to the procedure shown in FIG.

  The influence of noise generated inside the optical pulse measuring device will be described with reference to FIG. FIG. 9 shows the noise x generated inside the optical pulse measuring device and the reflected waveform when the second far-end optical communication device is connected to the second optical line. As indicated by the broken line in FIG. 9, the noise x overlaps the reflected pulses α and β. In this case, when the differential waveform is obtained, the reflected pulse γ becomes a jagged shape with severe irregularities, as shown in FIG. FIG. 10 shows noise x and noise level e generated inside the optical pulse measuring instrument. In the optical line test system according to the first embodiment, the test pass / fail determination means obtains the noise level e at which the reflection level due to the noise generated inside the optical pulse measuring device becomes the highest, and the reflection position is determined based on the noise level e. It is preferable to perform association. FIG. 11 shows a reflected waveform when the first far-end optical communication device with the noise level e as a reference is connected to the second optical line. FIG. 12 shows a reflected waveform when the second far-end optical communication device with the noise level e as a reference is connected to the second optical line. Since the noise level e is used as a reference, it is not affected by noise as shown in FIGS. FIG. 13 shows a differential waveform between the reflected waveform of FIG. 11 and the reflected waveform of FIG. 11 and 12, the reflected pulse β in FIG. 13 does not have a jagged shape, and the reflected pulse corresponding to the second far-end optical communication device (the reflected pulse in FIG. 12) is not affected by noise. (See β). Thereby, the optical line test system according to the first embodiment can accurately associate the reflection positions without being affected by noise.

  In the first optical line and the second optical line, backscattered light may be measured together with the reflected waveform in the optical line during the test. FIG. 14 shows a reflected waveform when the first far-end optical communication device when the noise x and the backscattered light y are measured is connected to the second optical line. Here, the reflected pulse δ is a reflected pulse corresponding to the far-end optical communication device. As shown in FIG. 14, the backscattered light level f is higher than the noise level e. Further, when the backscattered light y and the noise x overlap, the noise level e may change, and the test pass / fail determination means may erroneously associate the noise with the reflection position. In the optical line test system according to the first embodiment, the test pass / fail determination means obtains the backscattered light level f at which the reflection level of the backscattered light y is the highest with respect to the distance to the reflection position measured by the optical pulse measuring device, It is preferable to associate the reflection positions with reference to the backscattered light level f. As a result, the optical line test system according to the first embodiment can accurately associate the reflection positions without being affected by the backscattered light.

  The backscattered light level f may be calculated by using a dummy fiber at a factory or the like when the optical pulse measuring device is shipped. Alternatively, the optical pulse measuring device may include a dummy fiber inside so that the backscattered light level f can be measured at any time. Note that the noise width overlapping with the backscattered light correlates with the number of times of averaging, and taking this into account makes the correspondence of the reflection positions more accurate.

  When an optical connector is arranged between the optical pulse measuring device and the far-end optical communication device, a reflected pulse generated by the optical connector may be measured by overlapping with the backscattered light. FIG. 15 shows a reflected waveform when the first far-end optical communication device is connected to the second optical line when noise x, backscattered light y, and reflected pulse z generated at the optical connector are measured. Indicated. Here, when the reflected pulse z generated in the optical connector changes due to temperature change or aging deterioration of the optical connector, the reflected pulse z generated in the optical connector may be measured. In the optical line test system according to the first embodiment, the optical network has an optical connector disposed between the optical pulse measuring device and the far-end optical communication device, and the test pass / fail judgment means has a reflection level generated at the optical connector. It is preferable that the optical connector reflection level g with the highest z is obtained, and when the optical connector reflection level g is higher than the backscattered light level f, the reflection position is associated with the optical connector reflection level g as a reference. Thereby, the optical line test system according to the first embodiment can accurately associate the reflection positions without being influenced by the reflection level generated in the optical connector.

  If the reflection level of the reference optical connector is obtained from, for example, 40 dB, which is a typical reflection attenuation amount of the optical connector, there is no problem that the test pass / fail judgment means associates the wrong reflection position. . However, since the typical return loss varies depending on the optical connector, the method for obtaining the reflection level of the optical connector is based on the type of optical connector used in the corresponding optical line and the construction standard value for each type of optical connector. The reflection level of the reference optical connector may be used. When the optical connector deteriorates due to external factors and the return loss deteriorates to, for example, 20 dB. When the reflection level at the optical connector exceeds the optical connector reflection level g and also exceeds the reflection pulse δ. The test pass / fail determination means determines that a failure has occurred. Since the optical line test system according to the first embodiment is intended to detect a failure in the optical line, there is no operational problem even if a failure in the optical connector is detected.

(Second Embodiment)
The optical line test system according to the second embodiment will be described focusing on differences from the optical line test system according to the first embodiment. In FIG. 16, the schematic block diagram of the optical line test system which concerns on 2nd Embodiment was shown. The optical line test system according to the second embodiment includes a near-end optical communication device 10, eight far-end optical communication devices 30 that communicate with the near-end optical communication device 10, and an optical branch circuit 22 that branches into eight or more. The first optical line 20 that connects the near-end side optical communication device 10 and the optical branch circuit 22, and the eight second lines that connect the optical branch circuit 22 and the eight far-end side optical communication devices 30, respectively. An optical line test system 101 for testing an optical network having an optical line 24, which is inserted between eight far-end optical communication devices 30 and a second optical line 24, and reflects a test optical pulse. A test light pulse reflecting means 60 is connected to the first optical line 20 via a coupling circuit 52, emits a test light pulse toward the far-end optical communication device 30, and is a reflection level with respect to the distance to the reflection position. Optical pulse measuring instrument 50 for measuring light and optical pulse measuring instrument The optical loss between the coupling circuit 52 and the test optical pulse reflecting means 60 is obtained from the reflection level with respect to the distance to the reflection position measured by the optical pulse measuring device 50 by emitting the test optical pulse to 0, and the optical loss is calculated. And a test pass / fail judgment means 70 for judging the pass / fail of the test based on the Mth (where M is a positive integer of 8 or less) far-end optical communication device 30 is the second. The reflection level with respect to the distance to the reflection position when connected to the optical line 24 and the reflection with respect to the distance to the reflection position when the M−1th far-end optical communication device 30 is connected to the second optical line 24. The difference with the level is obtained, and the reflection position is associated with the Mth far-end optical communication device 30 with the distance to the reflection position having the highest reflection level in the difference. In FIG. 16, the third to seventh far-end optical communication devices and the second optical line are omitted, and the wireless communication unit 80 and the communication terminal 90 are shown. The wireless communication unit 80 has a function of performing wireless communication, for example.

  FIG. 17 shows a block diagram of the test pass / fail judgment means in the second embodiment. The test acceptance / rejection determination unit 70 is connected to the wireless communication unit 80 via the wireless interface 76.

  The communication terminal 90 in FIG. 16 is a terminal having a function of communicating wirelessly. For example, the communication terminal 90 is a mobile phone, a personal handy-phone system (PHS), a PDA (Personal Digital Assistant), and a notebook computer having a wireless communication function. is there. The optical line test system according to the second embodiment preferably further includes a communication terminal 90 that displays the pass / fail status of the test, and the test pass / fail determination means 70 preferably notifies the communication terminal 90 of the pass / fail status of the test. The optical line test system according to the second embodiment can notify the operator who has the communication terminal of the pass / fail of the test regardless of the location of the operator, and is convenient.

  As described above, the optical line test system according to the second embodiment is similar to the optical line test system according to the first embodiment. It is possible to specify which far-end optical communication device corresponds to the reflected pulse from the test optical pulse reflection means without obtaining the distance to the far-end optical communication device from the design drawing or actually measuring the distance. Further, the optical line test system according to the second embodiment obtains the optical loss as well as the failure of the optical line or the failure of the far-end side optical communication device, similarly to the optical line test system according to the first embodiment. Can be carved out.

(Third embodiment)
The optical line test system according to the third embodiment will be described focusing on differences from the optical line test system according to the second embodiment. In the optical line testing system according to the third embodiment, instead of the communication terminal 90 of FIG. 16, the optical network forwards a warning indicating that the near-end optical communication device 10 has passed or failed the test to the far-end optical communication device 30. Then, the far-end optical communication device 30 outputs the content of the warning according to the warning, and the test pass / fail determination means 70 transmits the warning to the near-end optical communication device 10 and forwards the warning to the far-end optical communication device 30. May be. Examples of means for outputting a warning provided in the far-end optical communication device 30 include an alarm lamp, a speaker that outputs an alarm sound or sound, and a display that outputs a warning text. The optical line test system according to the third embodiment can notify the operator near the far-end optical communication device 10 of the success or failure of the test, and is convenient.

  As described above, the optical line test system according to the third embodiment has the same effect as the optical line test system according to the second embodiment, and can transfer a warning using an existing optical network, so that the cost is low. is there.

  The optical communication system according to the present invention can be used in an optical network such as a PON (Passive Optical Network).

It is a schematic block diagram of the optical line test system which concerns on 1st Embodiment. It is a conceptual diagram which shows the form which inserts the test optical pulse reflection means between a far end side optical communication apparatus and a 2nd optical line. It is a block diagram of a test pass / fail determination means. It is a flowchart of the operation | work which connects a far end side optical communication apparatus to an optical branching means. It is a flowchart of a process of a test pass / fail determination means. It is a conceptual diagram which shows the reflected waveform when the 1st far end side optical communication apparatus is connected to the 2nd optical line. It is a conceptual diagram which shows a reflected waveform when the 2nd far-end side optical communication apparatus is connected to the 2nd optical line. It is a conceptual diagram which shows the difference waveform of the reflected waveform of FIG. 6, and the reflected waveform of FIG. It is the conceptual diagram which accumulated the noise which generate | occur | produces inside a pulse measuring device, and the reflected waveform when the 2nd far end side optical communication apparatus is connected to the 2nd optical line. It is a conceptual diagram which shows the noise and noise level which generate | occur | produce inside an optical pulse measuring device. It is a conceptual diagram which shows a reflected waveform when the 1st far end side optical communication apparatus on the basis of a noise level is connected to the 2nd optical line. It is a figure which shows a reflected waveform when the 2nd far-end side optical communication apparatus on the basis of a noise level is connected to the 2nd optical line. It is a figure which shows the difference waveform of the reflected waveform of FIG. 11, and the reflected waveform of FIG. It is a figure which shows a reflected waveform when the 1st far end side optical communication apparatus in case noise and backscattered light are measured is connected to the 2nd optical line. It is a figure which shows a reflected waveform when the 1st far end side optical communication apparatus in case noise, a backscattered light, and the reflected waveform which generate | occur | produces with an optical connector are measured is connected to the 2nd optical line. It is a schematic block diagram of the optical line test system which concerns on 2nd Embodiment. It is a block diagram of the test pass / fail determination means in the second embodiment.

Explanation of symbols

100, 101 Optical line test system 10 Near-end side optical communication device
20 1st optical line 22 Optical branch circuit 24, 24a 2nd optical line 30, 30a Far end side optical communication apparatus
50 Optical pulse measuring device 52 Coupling circuit 54 Optical switch 60, 60a Optical pulse reflection means for test 70 Test pass / fail judgment means 71 CPU
72 OLT interface 73 Optical switch interface 74 Optical pulse measuring instrument interface 75 Storage unit 75a ONU storage unit 75b Measurement condition storage unit 75c Measurement result storage unit 75d Noise level storage unit 75e Backscattered light level storage unit 75f Optical connector reflection level storage unit 76 Wireless interface 80 Wireless communication means 90 Communication terminal a, c Maximum reflection level b, d Distance from reflection position e Noise level f Back scattered light level g Optical connector reflection level x Noise y Back scattered light z Generated at optical connector Reflected pulse α, β, γ, δ Reflected pulse

Claims (8)

Near-end side optical communication device, N (N is a positive integer) far-end side optical communication device communicating with the near-end side optical communication device, optical branch circuit branching to N or more, and near-end side optical communication A first optical line connecting the device and the optical branch circuit, N second optical lines connecting the optical branch circuit and the N far-end optical communication devices, and the N far optical circuits, respectively. An optical line test system for testing an optical network, which is inserted between an end-side optical communication device and the second optical line and has a test optical pulse reflecting means for reflecting a test optical pulse,
An optical pulse measuring device connected to the first optical line via a coupling circuit, emitting the test optical pulse toward the far-end optical communication device, and measuring a reflection level with respect to a distance to a reflection position;
The light loss between the coupling circuit and the test light pulse reflecting means is calculated from the reflection level with respect to the distance to the reflection position measured by the light pulse measuring device by emitting the test light pulse to the light pulse measuring device. And a test pass / fail judgment means for judging pass / fail of the test based on the light loss,
The test acceptance / rejection determining means is a reflection level relative to a distance to the reflection position when the M-th (where M is a positive integer less than or equal to N) the far-end optical communication device is connected to the second optical line. And the M−1th far-end optical communication device is connected to the second optical line to obtain the difference between the reflection level with respect to the distance to the reflection position, and the highest reflection level among the differences An optical line test system, wherein a reflection position is associated with a distance to the reflection position corresponding to the M-th far-end optical communication device. Near-end side optical communication device, N (N is a positive integer) far-end side optical communication device communicating with the near-end side optical communication device, optical branch circuit branching to N or more, and near-end side optical communication An optical network having a first optical line connecting a device and the optical branch circuit, and N second optical lines respectively connecting the optical branch circuit and the N far-end optical communication devices. An optical line test system to be tested,
A test optical pulse reflecting means that is inserted between the N far-end optical communication devices and the second optical line and reflects the test optical pulse;
An optical pulse measuring device connected to the first optical line via a coupling circuit, emitting the test optical pulse toward the far-end optical communication device, and measuring a reflection level with respect to a distance to a reflection position;
The light loss between the coupling circuit and the test light pulse reflecting means is calculated from the reflection level with respect to the distance to the reflection position measured by the light pulse measuring device by emitting the test light pulse to the light pulse measuring device. And a test pass / fail judgment means for judging pass / fail of the test based on the light loss,
The test acceptance / rejection determining means is a reflection level relative to a distance to the reflection position when the M-th (where M is a positive integer less than or equal to N) the far-end optical communication device is connected to the second optical line. And the M−1th far-end optical communication device is connected to the second optical line to obtain the difference between the reflection level with respect to the distance to the reflection position, and the highest reflection level among the differences An optical line test system, wherein a reflection position is associated with a distance to the reflection position corresponding to the M-th far-end optical communication device. When the link is established between the near-end optical communication device and the M-th far-end optical communication device, the optical network transmits link information indicating that the link is established to the near-end. The side optical communication device transmits to the test pass / fail judgment means,
The optical path test system according to claim 1, wherein the test pass / fail determination unit associates the reflection positions after receiving the link information from the near-end optical communication device.   The test acceptance / rejection determining unit obtains a noise level at which the reflection level is highest due to noise generated inside the optical pulse measuring device, and associates the reflection position with the noise level as a reference. The optical line test system according to claim 1.   The test acceptance / rejection determination unit obtains a backscattered light level at which the reflection level of the backscattered light is highest with respect to a distance to the reflection position measured by the optical pulse measuring device, and the reflection position is based on the backscattered light level. The optical line test system according to any one of claims 1 to 3, wherein the correlation is performed. In the optical network, an optical connector is disposed between the optical pulse measuring device and the far-end optical communication device,
The test acceptance / rejection determination unit obtains an optical connector reflection level at which the reflection level generated at the optical connector is highest, and when the optical connector reflection level is higher than the backscattered light level, the optical connector reflection level is used as a reference. The optical path test system according to claim 5, wherein the reflection positions are associated with each other.   The optical line according to any one of claims 1 to 6, further comprising a communication terminal that displays the pass / fail of the test, wherein the test pass / fail determination means wirelessly notifies the communication terminal of the pass / fail of the test. Test system. The optical network transfers a warning indicating that the near-end optical communication device has passed or failed the test to the far-end optical communication device, and the far-end optical communication device outputs the content of the warning according to the warning. ,
The light beam according to any one of claims 1 to 7, wherein the test acceptance / rejection determination unit transmits the warning to the near-end side optical communication device and causes the warning to be transferred to the far-end side optical communication device. Road test system.

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