JP2006194589A - Method and device for testing optical cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method for simply performing a status test and the determination of a fault position on an optical cable used as an indoor lead-in wire without causing the optical cable to be permanently deformed. <P>SOLUTION: A palm-sized tool is provided which is carried by a worker as one of work tools for moderately pressing the optical cable and an optical fiber of the optical fiber for indoor leading-in at each position. This work tool uses returning force of a spring to press and deform the optical cable. Accordingly, the degree of bending loss occurring in the optical cable can be uniformed independently of the individuality of the worker. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is used for a line test associated with laying, maintenance and the like of a communication optical cable. The present invention is used in connection with construction for laying or maintaining an optical cable. In particular, it is used to conduct an open test for each section when newly laying an optical cable, or to search for and identify the location of a fault when communication faults such as signal disruption or communication quality degradation occur in existing optical cables. . The present invention relates to a test method and apparatus for specifying a fault location without cutting an optical cable to be searched. The present invention relates to a test apparatus and a test method for finding a defective part by a simple operation while being able to be carried as a tool by a worker on site.

  Conventionally, in optical cable laying construction and fault location search processes, there is a method for easily specifying the position by temporarily bending a part of the optical fiber and giving a bending loss to the optical signal passing through the optical cable. Are known. Briefly explaining this example, when an operator wraps a part of a connecting optical fiber around a rod-shaped tool such as a screwdriver at an optical cable connection point or the like, a part of the optical fiber is temporarily set to a predetermined part. A portion having a radius of curvature smaller than the allowable bending radius of curvature is formed. As a result, a state in which the bending loss of the optical fiber is increased at a portion having a small radius of curvature, and the position can be identified by observing this from the end of the optical fiber with a pulse signal.

  Explaining this exemplarily, it is assumed that some defective portion occurs in the optical cable and the optical signal is not properly propagated. At this time, an optical signal test device is connected to one end of the optical fiber in a telecommunications company's office or the user's home terminal, and an extremely short pulse optical test is performed from the test device to the optical fiber. Send a signal. Then, since the reflection due to the optical test signal becomes extremely large at the defective portion, the approximate distance to the defective portion is estimated by the elapsed time from the transmission timing of the pulsed optical test signal to the reception timing of the reflected signal. can do.

  An operator goes to the site where the defective part is presumed and wraps the optical cable around the tool as described above. Then, the bending loss increases at the position where the tool is wound, and a step is observed in the magnitude of the backscattered light with respect to the optical test signal. Thereby, it can be known whether the defective part is ahead or near the position where the tool is wound. Furthermore, when the reflected signal is observed on the time axis, if the position where the tool is wound is in front of the defective portion, it can be known how many meters away from the position where the tool is wound. .

  In an optical cable used conventionally, even if a small mechanical bend is given to the optical fiber by such work, the optical signal transmission characteristic of the optical cable is restored to its original state by releasing the bend. In general, experienced workers are well aware of how much bending should be applied to an optical cable so that the optical signal transmission characteristics of the optical cable change permanently during the work. There is no such extreme bending. However, if bending with a curvature smaller than the allowable value is given for some reason, physical deformation occurs in the optical fiber, the bent state cannot be recovered, and permanent bending loss occurs.

For this reason, to work as described above, when temporarily bending, it is not appropriate to simply use a driver carried by the operator, and a special optical fiber is wrapped around. Tools for this are also known. This tool has, for example, a structure in which a plurality of short bar-shaped protrusions are provided on a small flat plate, and has a form in which an optical fiber is entangled with the bar-shaped protrusions in an S shape or a U shape. By appropriately designing the thickness of the rod-like protrusions and the arrangement interval thereof in accordance with the mechanical characteristics of the optical cable, the optical fiber entangled in the S-shape is given a bend with a radius of curvature less than the specified value. In addition, it can be designed so that an appropriate bending loss can be generated in the optical signal passing through the optical fiber by this bending.
JP-A-7-63645 (Advantest)

Here, as an optical cable drawn into the user's home, a new type different from the above conventional example has been frequently used. FIG. 5 shows a cross-sectional structure diagram and an external perspective view of the new type optical cable. The optical cable 10 having the form shown in FIG. 5A has a structure in which an optical fiber 2 is disposed between a pair of tension members 1 and the pair of tension members 1 and the optical fiber 2 are fixed with a plastic layer 3. The optical cable having this structure is relatively solid and has an excellent property in that there is almost no change in signal transmission characteristics due to construction or due to aging. As an example of the standard of the optical cable having this structure, w ₁ = 3.0 mm and h = 1.6 mm with reference to FIG. The optical cable of this standard is planned to be used mainly as a branch wiring to the user's house.

The optical cable of the form shown in FIG. 5B is a drop cable with a support line. The drop cable having this structure is mainly used in the form of installing an optical cable as a single wiring outdoors. The drop cable with a support line shown in FIG. 5 (b) has a structure in which a support line 20 made of steel having a diameter of about 1.3 mm is disposed along the optical cable and the whole is solidified with a plastic layer. As an example of the standard of this optical cable, referring to FIG. 5B, w ₂ = 5.0 mm and h = 1.6 mm.

  FIG. 6 shows an example of the usage pattern. That is, the optical terminal box 12 is arranged in the utility pole 16 or the manhole 17 which is separated by a suitable distance from the telephone company office building 11 through a high-speed optical cable installed underground. A high-speed optical cable 13 is connected from the station building 11 to the optical terminal box 12. Between the optical terminal box 12 and the home terminal 14 of each user, wiring is performed using the drawing optical cable 10 or the drop cable 15 with a support wire. The pull-in optical cable 10 and the drop cable 15 with a support line are the object of the present invention.

  This optical cable 10 is set to a radius of curvature with a large bending allowance, and can be wired with an appropriate curvature along the walls and pillars of the building. The optical fiber 2 that is the core wire does not have a bending loss sufficient for measurement. Furthermore, if the drop cable 15 with a support line is bent to such an extent that it can be identified by the terminal, the support line 20 is almost mechanically broken. In general, it is impossible to restore this to the extent that the support wire 20 can withstand sufficient mechanical tension. Some workers, for the purpose of temporarily confirming the position during construction, peel off the connection portion with the support wire 20 and bend only the plastic layer 3 portion. Such a construction is not generally acceptable because it will permanently damage the cable for testing.

  The present invention has been made in such a background, and even when the above-described optical cable for retracting is used, the position where the worker in the field accesses the optical cable can be easily recognized from the end of the optical cable. It is an object to provide a method and apparatus that can be used. In other words, the present invention relates to a drawing optical cable in which an optical fiber is held between a pair of tension members without temporarily cutting the optical cable and irreparably damaging the optical cable. It is an object of the present invention to provide a method and an apparatus capable of recognizing a position by giving a bending loss to and setting the backscattered light discontinuously. The present invention also applies to a drop cable with a supporting line, and the backscattered light generated by temporarily bending the optical signal without causing irreparable damage to the cable is discontinuous at that position. It is an object of the present invention to provide a method and an apparatus that can identify the position. An object of the present invention is to provide a simple jig that can be carried by a worker who lays or maintains an optical cable and that is used for finding a defective portion of the optical cable. An object of the present invention is to provide a jig used for searching for a defective portion of an optical cable without permanent damage to the optical cable, regardless of the skill level of the worker on site. An object of the present invention is to rationalize work by reducing the work man-hours of an optical cable maintainer.

  The first aspect of the present invention is an optical cable testing method invention, in which an operator who accesses an optical cable does not bend the optical cable as a whole, but selectively selects an optical fiber portion held between a pair of tension members. The greatest feature is that the test is performed with a temporary bending loss by deforming. That is, the present invention selectively presses the optical fiber portion of the optical cable in which the optical fiber (2) is held by the plastic layer (3) formed between the pair of tension members (1). Is temporarily bent, and in response to the bending, a temporary bending loss is caused in an optical signal propagating in the optical fiber. In this state, by transmitting a test signal to the optical fiber and observing the response to the test signal, the relative position between the position where the temporary bending loss was caused and the position where the optical cable should be accessed Recognize relationships. The response preferably uses backscattered light generated inside the optical fiber with respect to the test signal. One end of the optical cable includes a lead-in wire that is drawn into the user's home, and the test signal can be transmitted from a home terminal of the lead-in wire provided at the user's home. A test signal can be transmitted to the optical cable before and after the bending loss is generated (whichever is first), and the response to the test signal can be compared.

  In the embodiment of the present invention, a small amount of bending loss is caused from the optical fiber selectively with respect to the optical fiber portion of the optical cable in which the optical fiber is held by the plastic layer formed between the pair of tension members. However, a jig set so as to give mechanical deformation to such an extent that it does not lead to permanent deformation is used. This jig will be described later as a second invention. The optical fiber is temporarily deformed by the jig, a test signal is transmitted inside the optical fiber, and a response to the test signal is observed.

  The response preferably uses backscattered light generated inside the optical fiber with respect to the test signal. When the one end of the optical cable is an optical cable drawn into the user's house, the test signal can be transmitted from an optical communication terminal provided at the user's house. A test signal can be transmitted to the optical fiber before and after applying the mechanical deformation, and the responses to the test signals before and after that can be compared with each other.

  The second aspect of the present invention is an invention of a test jig. The base (6), the lever (8) pivotally attached to the base (6), and the lever (8) are driven around the axis. A spring member (9) to be operated, a groove member (7) disposed at a position where the lever (8) presses the base (6) by a repulsive force of the spring member (9), and the lever (8) And a pin (5) for selectively pressing the position of the optical fiber (2) of the optical cable (10) received in the groove of the groove member (7). By using this test jig, the optical fiber portion of the optical cable in which the optical fiber (2) is held by the plastic layer (3) formed between the pair of tension members (1) is used. Optionally, a small amount of bending loss can be produced from the optical fiber, but mechanical deformation can be applied to such an extent that does not result in permanent deformation.

  It is desirable to dispose an elastic body (7a) at the bottom of the groove formed in the groove member. By arranging the elastic body (7a) at the bottom, only the portion of the optical fiber (2) of the optical cable (10) pressed by the pin (5) is deformed, and the deformation does not reach other portions. Can be set to The groove member (7) can be formed integrally with the base (6), or can be formed as a separate member to be mounted on the base (6).

  The groove member (7) is configured as a separate member, and a plurality of different types of standards corresponding to the optical cable standard are prepared, and one of these is selected and used. be able to. In the groove member, a plurality of grooves having different standards are formed in one member, and the mounting position of the groove member with respect to the base is changed according to the type of the optical cable to be tested. It can be configured to use one. The groove member has a structure in which two grooves corresponding to two different standards are formed in one member, and the mounting direction of the groove member with respect to the base is changed according to the type of optical cable to be tested. It can be. In the groove member, by setting a groove structure that can accommodate an optical cable having a lead-in support line formed in an integral structure without separating the support line, a drop cable with a support line that is generally difficult to bend is provided. However, it can be used without performing work such as separating the support wire.

  Furthermore, the present invention is an apparatus for performing a test using the above test jig, and comprises means for transmitting an optical signal to an optical cable and means for receiving a response signal for the optical signal from the optical cable. The transmitting means, the receiving means, and the means for connecting the two means to the user's home terminal are preferably configured as one portable device.

  The test method and apparatus according to the present invention selectively presses an optical fiber portion of an optical cable with a constant repulsive force by a spring member provided on a jig, and the force or It does not adjust the force that temporarily deforms the optical cable. Therefore, even if the workers are different, even if the worker is unfamiliar with the scale, all the forces for temporarily deforming the optical fiber are uniform. That is, the bending loss that occurs temporarily and forcibly becomes uniform regardless of the individuality of the operator. As a result, even if the optical fiber is deformed in the field, it is not possible to correctly observe this from the end of the optical fiber. In addition, it is possible to eliminate inconveniences such as the force that is temporarily applied to the optical cable during the test and the optical cable is damaged.

  The jig of the present invention is small and light, and can be carried by a worker in a tool bag as one of tools and used at any time on the work site. Furthermore, in using the jig of the present invention, it is assumed that two workers, a person who installs the jig on the line, and a person who injects an optical signal from the end of the line to perform the test are required. However, the jig of the present invention maintains the state in which bending loss is given to the optical fiber even if the hand is released after being attached to the optical cable. Therefore, even when there is only one worker and no other worker can be obtained through the optical cable, it is possible to sequentially perform operations such as mounting a jig on the optical cable and testing the optical cable. it can.

  The jig of the present invention can also be used appropriately for a drop cable in which thick support wires are mounted in parallel. In other words, it is not necessary to perform an irreparable operation such as disconnecting the supporting cable of the drop cable, and the optical fiber part can be appropriately deformed to give bending loss without damaging the cable. When the jig was removed, the bending loss disappeared, and it was confirmed that the passing signal was restored.

Example 1
First, the jig structure of the embodiment of the present invention will be described. FIG. 1 is a perspective view of a prototype jig according to the present invention. This jig was prepared to be carried by a worker who went to the work site as one of the work tools in a tool bag. Its size is about to be placed on the palm of a person, with a side of about 50 mm and a thickness of about 18 mm. This jig is used by an operator on an electric pole or in a manhole to access a working optical cable and temporarily deform a part thereof to give a bending loss. Except for the spiral spring member 9, the shaft for supporting the spring member 9, and the mounting pin, they are all made of a plastic material.

  A groove member 7 having one groove formed on the upper plane is attached to the base 6. In this embodiment, the groove member 7 is a single rectangular parallelepiped member, and a single groove that can accommodate a part of the optical cable to be tested is formed on the upper surface thereof. The groove member 7 is attached to the end of the base 6. Although not visible in this drawing, two small pins are embedded in the groove member mounting surface of the base 6. At the bottom of the groove member 7, there are provided two small holes that fit into the pins. The two pins are each fitted into the small hole. With this structure, the mounting position of the groove member 7 with respect to the base 6 is fixed.

  The groove formed on the upper surface of the groove member 7 has a rectangular shape with a width of about 3.5 mm and a depth of about 2.0 mm. This is just a shape that can accommodate a portion of a standard optical cable. In this groove, a part of the optical cable 10 connected to the line can be accommodated as it is without disconnecting the line connection. An elastic body 7a is disposed at the bottom of the groove. The elastic body 7a is a thin rubber plate. The back surface of the elastic body 7a is bonded to the bottom of the groove.

  The lever 8 is formed of a plastic member. In FIG. 1, the lever 8 is drawn as a transparent plastic member, but this is drawn so that the structure of the spring member 9 below the lever 8 portion is easy to understand. Specifically, the plastic member constituting the lever 8 may be an opaque material. A lever 8 is pivotally attached to the base 6 so as to be rotatable. A spring member 9 is mounted around the axis. The return force of the spring member 9 acts between the lever 8 and the base 6, and the lever 8 generates a rotational force indicated by an arrow A around its axis.

  A pin 5 is provided on the lever 8 near the tip of the lever 8. The pin 5 penetrates the tip member of the lever 8, and the tip portion slightly protrudes toward the inside of the upper groove of the groove member 7. FIG. 2 shows an enlarged cross-sectional view. In other words, the protruding tip portion of the pin 5 is tapered and the tip is somewhat rounded. The tip of the pin 5 has a structure that abuts against the center of the optical cable 10 placed in the groove at the center position of the groove in a state where the return force of the spring member 9 acts on the lever 8. Yes. That is, the pin 5 abuts on an optical fiber portion mounted on the optical cable 10 and acts to slightly deform the optical fiber according to its tip shape. This deformation causes a slight bending loss in the optical signal transmitted to the optical fiber.

  In order to use this jig shown in FIG. 1, the pin 5 is separated from the upper surface of the groove member 7 when a force is applied to the lever 8 as indicated by an arrow B with fingers. In this state, a part of the currently used optical cable 10 is submerged in the upper surface groove of the groove member 7 without being cut off, while being connected. When the force of the finger applying the force as shown by the arrow B is loosened, the lever 8 rotates as shown by the arrow A by the return force of the spring member 9, and the tip of the pin 5 presses the central portion of the optical cable 10. To do.

  Referring to FIG. 2, the tip of the pin 5 acts so as to press the central portion of the optical cable 10 downward. As a result, the optical fiber 2 located at the central portion of the optical cable 10 is locally deformed to a small extent, and a small bending loss is generated in the optical signal passing through this portion. This pressing force is not a force of a human finger but a repulsive force of the spring member 9. Therefore, this pressing force is a uniform pressing force without variation due to the operator's control when the operator releases his / her finger from the lever 8. That is, by designing the tip shape of the pin 5, the shape of the lever 8, the repulsive force strength of the spring member 9, the thickness or elasticity of the elastic body 7 a according to the hardness of the optical cable 10, The internal optical fiber 2 can be deformed locally and uniformly. Due to this deformation, a part of the optical signal passing through the inside of the optical fiber 2 leaks to an appropriate degree at this deformation position, and bending loss is generated. When the force giving this deformation is released, the optical fiber 2 is restored by the elasticity of the plastic layer of the optical cable, and the bending loss of the optical signal passing through the optical fiber 2 disappears and is restored.

  In this embodiment, a plurality of groove members 7 having different shapes and widths are prepared as the groove member 7, and one that matches the optical cable to be tested is selected and used. Configured. That is, by appropriately replacing the groove member 7 attached to the base 6, a single jig can be used for a plurality of optical cables with different standards.

  As described above in the section of the subject of the present invention, this operation is performed by communicating with fellow workers who detect the transmission of an optical signal and the response to the optical signal at the end of the optical cable 10. A defective portion of the optical cable 10 can be found appropriately. That is, one worker at the site uses the jig shown in FIG. 1 to access the optical cable 10 to give an appropriate bending loss to the optical cable 10, and another person is positioned at the end of the optical cable 10 to send a signal. Work while observing with the cell phone etc. As a result, it is possible to properly identify in which direction and how much the defective portion of the optical cable 10 is displaced from the position deformed by the jig.

  FIG. 3 shows a signal connection system diagram of the optical cable to be tested. This is an example in which this position is searched assuming that there is a defective portion in the optical cable 10 between the home terminal 14 and the utility pole 16. One worker accesses the home terminal 14 installed in the user's home and connects the measuring device 19 to the home terminal 14. The measuring device 19 transmits a short optical pulse signal from the optical pulse transmitter 21 to the in-home terminal 14 via the coupler 18, and receives and observes the level of the backscattered light generated by the optical cable with respect to the optical pulse signal. . That is, the backscattered light is branched by the coupler 18 and received by the optical signal receiver 22. The received optical reception signal is displayed on the display 23 as a level change on the time axis. Since such a measuring device 19 is well known as OTDR, further detailed description is omitted here.

  The test procedure will be described. An operator who carries the jig according to the embodiment of the present invention and accesses an appropriate position of the optical cable 10 is an operator who operates the measuring device 19 using a mobile phone or a transceiver. 1 is attached to the optical cable 10 while contacting with the optical cable 10. Then, for example, a waveform as shown in FIG. 4A appears as a display waveform observed on the screen of the display 23 of the measuring device 19. The display waveform shown in FIG. 4A shows that when a short light pulse is transmitted from one end of the optical cable 10 to the optical cable 10, the backscattered light generated inside the optical cable 10 is reflected at the transmission point of the optical pulse. It is a waveform observed and displayed on the time axis.

  FIG. 4 shows the elapsed time from the time when the optical pulse is transmitted to the optical cable 10 on the horizontal axis, which corresponds to the distance of the optical cable 10 as it is. The level of the reflected response light signal is displayed on the vertical axis. 4A and 4B show the results of testing with an optical cable having an allowable bending radius R30. FIGS. 4C and 4D show the results of testing with an optical cable having an allowable bending radius R15.

In the test results shown in FIGS. 4A and 4B, a level difference is observed at the distance L ₁ . That is, when a short optical pulse signal is transmitted to the optical cable 10, the optical pulse signal propagates through the optical cable 10 while generating backscattered light. It can be observed that the signal level of the optical pulse signal is lowered at the position where the operator attaches the jig to the optical cable 10 and a slight bending loss occurs in the optical cable 10. Further, the optical pulse point continues to propagate through the optical cable 10 while generating backscattered light.

4C and 4D are test examples when the optical cable 10 is broken. Similarly to the above, an optical pulse signal is transmitted from the home terminal 14 to the optical cable 10, and the signal level of the response light is observed on the time axis, that is, on the distance axis. In this example, the optical cable is preliminarily cut on the electric pole 16 on a trial basis, and the jig according to the embodiment of the present invention is mounted at a position somewhat closer to the home terminal 14 from the cut point. Figure 4 appears response waveform corresponding to the mounting position of the jig to the distance L ₂ (c), the distance L ₃
A response corresponding to the breaking position of the optical cable appears. Therefore, by attaching the jig of the embodiment of the present invention to the front side of the break point of the optical cable in which breakage occurred, by performing the same observation as this, how far the break point is from the jig mounting position You can know if it is in position. That is, the distances L ₂ and L ₃
From this difference, it is possible to know how far the optical cable break point is from the position where the jig is mounted.

  Since the above description is a test example, it was explained that “cut in advance for testing”. Practically using this apparatus and method, in order to search for the fault position of the optical cable where the fault has occurred, the apparatus illustrated in FIG. 3 is connected to a home terminal or a branch terminal on a utility pole or a manhole, While moving the mounting point of the jig little by little, the failure position where the fracture or the characteristic has deteriorated is searched and found. The jig according to the present invention does not require any manual adjustment for the operator's operation, and bends to an optical signal uniformly and optimally once it is attached to the optical cable, regardless of the individuality of the operator. Loss can be given. If the apparatus and method of the present invention are used, the optical cable is completely restored to the original state when the jig is unmounted, and the bending loss generated temporarily disappears completely. By utilizing the apparatus and method of the present invention, there is no possibility that effective measurement cannot be performed due to the skill level of the operator, or that the optical cable is permanently damaged by the measurement.

  About the said Example, the bending loss which generate | occur | produces in an optical cable can be enlarged by enlarging the repulsive force of the spring member 9 of the jig | tool illustrated in FIG. 1, or forming the front-end | tip shape of the pin 5 sharply. By increasing the bending loss, the level change point shown in FIG. 4 can be clearly observed. However, if the change point of the level is conspicuous, the optical cable is damaged by mounting the jig of the embodiment of the present invention. If various tests are repeated and the level difference is set to be about 1 dB ± 0.5 dB in the observation results illustrated in FIG. 4, there is no inconvenience in the level observation of the reflected signal, and the optical cable is permanent. It has been confirmed that the present invention can be practiced without modification.

  Although the above embodiment has been described as observing by two people, the present invention can also be implemented when there is only one worker going to the site. That is, the jig of the present invention allows the operator to leave the position while pressing the optical cable as described above. Since the jig of the present invention has a stable structure, it can be left for several minutes or several hours with the jig attached to the optical cable. Therefore, even if the other party who transmits and observes the optical signal cannot be obtained from the end of the optical cable, it is possible to use the measuring device by leaving the site and going to the transmitting / receiving end of the device. It is.

(Second embodiment)
Next, another structure of the groove member 7 of the embodiment jig of the present invention will be described. Referring to FIG. 7, in this second embodiment, two types of grooves having different widths are formed in advance in one groove member 7. Of these two types of grooves, the narrow one is formed so that it can just accommodate the optical cable 10 described with reference to FIG. The wide groove is configured to accommodate the drop cable 15 with a support wire described in FIG. The groove member 7 is attached to the base 6 so as to be rotatable around the axis of the pin 24 by a single attachment pin 24 inserted from the back surface. For easy understanding in the drawing, the mounting position of the mounting pin 24 is indicated by a one-dot chain line.

  Therefore, when the groove member 7 is rotated around the axis of the pin 24 and set so that the narrow groove is located immediately below the position of the pin 5 as shown in FIG. It can be used to cause bending loss. When the groove member 7 is rotated around the axis of the pin 24 so that a wide groove is positioned immediately below the pin 5 as shown in FIG. 7B, the drop cable 15 with a support line is small. It can be used so as to cause a moderate bending loss. Since other structures can be understood in the same manner by the description of the above embodiment, further detailed description is omitted.

  By using the jig having this structure, it is possible to deal with both the cable in the form of the optical cable 10 and the cable in the form of the drop cable 15 with a support wire with a single jig. That is, the worker who is going to the site only needs to carry one jig.

  The number of mounting pins 24 of the groove member 7 is not necessarily one, but may be two or three. In this case, when changing the direction of the groove member 7, it is necessary not to simply rotate it around the axis of the mounting pin 24 but to remove the groove member 7 and then change the direction and insert it. .

In the communication lines of telecommunications carriers, for example, Nippon Telegraph and Telephone Corporation (NTT), a large number (about 30 million lines) of optical cable home terminals are planned for the next several years. Although the structure of the present invention and the structure of the jig are simple at first glance, in these construction work, the effect of reducing the number of work steps obtained by carrying out the present invention is remarkable, leading to a very large economic effect as a whole. It is expected to be. In particular, it is expected that a situation where “the test has resulted in failure” or “a sufficient test was not performed because of fear of failure” can be avoided in large quantities. In addition, when performing such a large amount of construction, the method and apparatus of the present invention are extremely effective for carrying out a uniform level of construction even if the experience and skill level of the worker is not sufficient, and the defects that occur It is expected that the construction rate may be significantly reduced.

The perspective view of the Example jig | tool of this invention (1st Example). The cross-section figure explaining the effect | action of this invention Example apparatus. The test system | strain diagram of an Example of this invention. The wave form diagram for evaluating a test by the example of the present invention. 1 is a structural diagram of an optical cable that is an object of an embodiment of the present invention. The figure which shows the structural example of the optical cable network by which this invention is implemented. The perspective view of the Example jig | tool of this invention (2nd Example).

Explanation of symbols

1 Tension member 2 Optical fiber 3 Plastic layer 5 Pin 6 Base 7 Trough (groove)
7a Elastic body 8 Lever 9 Spring member 10 Optical cable 11 Station 12 Optical terminal box 13 High-speed optical cable 14 Home terminal 15 Drop cable 16 with support line Utility pole 17 Manhole 18 Coupler 19 Measuring device 20 Support line 21 Optical pulse transmitter 22 Light Signal receiver 23 Display 24 Mounting pin

Claims (13)

By selectively pressing the optical fiber portion of the optical cable in a form in which the optical fiber is held by the plastic layer formed between the pair of tension members, a temporary bending loss is caused in the optical fiber, A test method for an optical cable, comprising: transmitting a test signal to an optical fiber and observing a response to the test signal. The optical cable testing method according to claim 1, wherein the response is backscattered light generated inside the optical fiber with respect to the test signal. The cable test method according to claim 2, wherein the test signal is transmitted from an in-home terminal of a lead-in wire provided in the user's home. 3. The optical cable testing method according to claim 2, wherein a test signal is transmitted to the optical cable before and after causing the bending loss, and a response to the test signal is compared. A base, a lever pivotally attached to the base, a spring member for driving the lever around the axis, and a groove disposed at a position where the lever presses the base by the repulsive force of the spring member An optical cable testing jig, comprising: a member; and a pin that is provided on the lever and selectively presses an optical fiber position of the optical cable received in the groove of the groove member. The optical cable test jig according to claim 5, wherein an elastic body is disposed at a groove bottom of the groove member. 6. The optical cable testing jig according to claim 5, wherein the groove member is a separate member configured to be detachable from the base. The optical cable test jig according to claim 7, wherein a plurality of the groove members are prepared in accordance with optical cable standards. The groove member has a structure in which a plurality of grooves having different standards are formed in one member, and the mounting position of the groove member on the base can be changed according to the type of optical cable to be tested. The test jig for the optical cable described.
The groove member has a structure in which two grooves are formed in one member corresponding to two different standards, and the mounting direction of the trough to the base is changed according to the type of optical cable to be tested. 9. An optical cable testing jig according to 9. 11. The optical cable testing jig according to claim 8, wherein the groove member is set to have a structure capable of accommodating an optical cable having a lead-in support line formed in an integral structure without disconnecting the support line. 6. An optical cable testing apparatus, comprising: means for transmitting an optical signal to the optical cable; means for receiving a response signal for the optical signal from the optical cable; and the test jig according to claim 5. 13. The optical cable testing apparatus according to claim 12, wherein the transmitting means, the receiving means, and the means for connecting the input / output terminals of the two means to an optical communication terminal are configured as one portable device.

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