JP5562141B2 - Optical pulse test method and optical pulse test apparatus - Google Patents

Description

  The present invention relates to an optical pulse test method and an optical pulse test apparatus that perform OTDR (Optical Time Domain Reflectometry) measurement.

  In order to measure the loss of the optical transmission line, etc., OTDR measurement is performed. In OTDR measurement, pulsed light from a light source is output to a measured optical fiber, and the optical power of backscattered light in the measured optical fiber is measured. Pulse light from the light source is output to the optical fiber to be measured through a dummy fiber in the apparatus. A method for improving the accuracy of OTDR measurement by measuring the backscattered light level in the dummy fiber has been proposed (see, for example, Patent Document 1). The method described in Patent Document 1 calculates the light level of the backscattered light of the measured optical fiber using the light level of the backscattered light in the dummy fiber and the light level of the backscattered light after connecting the measured optical fiber. To do.

JP-A-6-160197

  When it is desired to accurately perform OTDR measurement of a long-distance optical fiber to be measured, pulse light having a wide pulse width is used in order to increase the SN ratio. At this time, unless the dummy fiber is lengthened, the light level of the backscattered light in the dummy fiber cannot be measured. That is, it is not possible to measure the light level of the backscattered light at the input / output end (end of the dummy fiber) of the optical pulse test apparatus to which the optical fiber to be measured is connected.

  In the method described in Patent Document 1, the pulse width of the pulsed light is not taken into consideration. For this reason, when the method described in Patent Document 1 is used, there is a problem that the dummy fiber becomes longer, the optical pulse test apparatus becomes larger, and the cost increases.

  Accordingly, an object of the present invention is to provide an optical pulse test method and an optical pulse test apparatus capable of accurately performing OTDR measurement of an optical fiber to be measured over a long distance using a short dummy fiber.

  In order to achieve the above object, the optical pulse test method of the present invention is configured such that a first pulse light having a first pulse width that is equal to or less than a time corresponding to a dummy fiber length is incident on the dummy fiber. In the first measurement procedure (S101) for measuring the light level of the first return light in which the first pulsed light is scattered by the dummy fiber, and the optical fiber to be measured is connected to the dummy fiber, Second pulse light having a second pulse width wider than the first pulse width is incident on the dummy fiber, and the second pulse light is scattered by the dummy fiber and the optical fiber to be measured. The second measurement procedure (S102) for measuring the light level of the second return light that has been performed, the first pulse width, the second pulse width, and the light level of the first return light, Above Return light of an input / output end that is an end of the dummy fiber on the side to which the optical fiber to be measured is scattered, in which the second pulse light of the two return light levels is scattered by the dummy fiber And an input / output end return light level calculation procedure (S103) for calculating the level.

  By executing the first measurement procedure, the light level of the return light from the dummy fiber at the first pulse width can be measured. By narrowing the first pulse width, the light level of the first return light at the input / output end can be measured even with a short dummy fiber. By executing the second measurement procedure, it is possible to measure the optical level of the return light from the optical fiber under measurement when the second pulse width is wide. The light level of the return light scattered by the dummy fiber at the second pulse width is increased according to the power ratio between the first pulse light and the second pulse light. Therefore, the light level of the return light at the input / output end can be calculated by executing the input / output end return light level calculation procedure. As described above, since the optical pulse test method of the present invention can calculate the optical level of the return light at the input / output end, even if a short dummy fiber is used, OTDR measurement of the optical fiber to be measured is performed. It can be performed with high accuracy. Therefore, the optical pulse test method of the present invention can accurately perform OTDR measurement of a long-distance optical fiber to be measured using a short dummy fiber.

  In the light pulse test method of the present invention, the light level of the second return light measured in the second measurement procedure and the light level of the return light of the input / output end calculated in the input / output end return light level calculation procedure are calculated. And a total loss value calculation procedure (S111) for calculating a loss value of light in the optical fiber to be measured may be further included after the input / output end return light level calculation procedure.

  In the optical pulse test method of the present invention, the total loss value display procedure (S112) for displaying the loss value of light in the measured optical fiber calculated in the total loss value calculation procedure is performed after the total loss value calculation procedure. Furthermore, you may have.

  In the optical pulse test method of the present invention, it is determined whether or not the light loss value calculated in the total loss value calculation procedure exceeds a predetermined threshold value, and a threshold value determination for displaying a determination result A procedure (S113) may be further included after the total loss value calculation procedure.

  In the optical pulse test method of the present invention, the marker display procedure (S121) for displaying a marker at the light level of the return light at the input / output end calculated in the input / output end return light level calculation procedure is used. You may have further after a level calculation procedure.

  In the optical pulse test method according to the present invention, the second return light at the incident end of the second pulsed light of the optical fiber under measurement is measured using the optical level of the second return light measured in the second measurement procedure. The measured optical fiber incident light level calculation procedure (S131) for calculating the return light optical level after the second measurement procedure, and the light level calculated in the input / output end return light level calculation procedure, A connection loss value calculation procedure (S132) for calculating a connection loss value between the dummy fiber and the measurement optical fiber using the light level calculated in the measurement optical fiber incident light level calculation procedure, You may have further after the output end return light level calculation procedure.

  The optical pulse test method of the present invention may further include a connection loss value display procedure (S133) for displaying the connection loss value calculated in the connection loss value calculation procedure after the connection loss value calculation procedure. .

  In the optical pulse test method of the present invention, a second line that displays the light level of the second return light measured in the second measurement procedure and the light level calculated in the measured optical fiber incident light level calculation procedure is displayed. The return light estimated straight line display procedure (S134) may be further provided after the input / output end return light level calculation procedure.

  In order to achieve the above object, an optical pulse test apparatus according to the present invention includes a light source (11) for outputting pulsed light, an input / output port (12) connectable to a measured optical fiber (100), and the input / output. A dummy fiber (13) connected to the port and outputting the pulsed light from the light source to the optical fiber to be measured connected to the input / output port; and a first that the pulsed light is scattered by the dummy fiber A light receiving unit (14) that receives the second return light in which the return light or the pulsed light is scattered by the dummy fiber and the optical fiber to be measured, and the first return light and the first light received by the light receiving unit. And a display unit (16) for displaying a calculation result of the calculation unit, and the light source has a dead zone whose length is the length of the dummy fiber. In The first pulsed light having the first pulse width that is equal to or shorter than the corresponding time is output, and the second pulsed light having the second pulse width wider than the first pulse width is output. The light receiving unit receives the first return light in which the first pulse light is scattered by the dummy fiber, and the second pulse light is scattered by the dummy fiber and the optical fiber to be measured. The second return light is received, and the calculation unit uses the first pulse width, the second pulse width, and the light level of the first return light received by the light receiving unit to perform the second return light. The optical level of the return light at the input / output end, which is the end of the dummy fiber on the side to which the optical fiber to be measured is scattered, in which the second pulse light of the return light is scattered by the dummy fiber I / O end return light level Comprising Le calculating portion (51).

  Since the light source outputs the first pulse light and the light receiving unit receives the first return light, the light level of the return light from the dummy fiber at the first pulse width can be measured. By narrowing the first pulse width, the light level of the first return light at the input / output end can be measured even with a short dummy fiber. Since the light source outputs the second pulse light and the light receiving unit receives the second return light, the optical level of the return light from the optical fiber to be measured at the second pulse width having a wide pulse width is measured. be able to. The light level of the return light scattered by the dummy fiber at the second pulse width is increased according to the power ratio between the first pulse light and the second pulse light. Therefore, the input / output end return light level calculation unit can calculate the light level of the return light at the input / output end. As described above, since the optical pulse test apparatus according to the present invention can calculate the optical level of the return light at the input / output end, even if a short dummy fiber is used, the OTDR measurement of the optical fiber to be measured is performed. It can be performed with high accuracy. Therefore, the optical pulse test apparatus of the present invention can accurately perform OTDR measurement of a long distance optical fiber to be measured using a short dummy fiber.

  In the optical pulse test apparatus according to the present invention, the calculation unit uses the light level of the second return light and the light level of the return light at the input / output end to use the second pulse light in the optical fiber to be measured. There may be provided a total loss value calculation unit (52) for calculating the loss value.

  In the optical pulse testing device of the present invention, the display unit may further include a total loss value display unit (62) for displaying a loss value calculated by the total loss value calculation unit.

  In the optical pulse test apparatus of the present invention, the calculation unit determines whether or not the loss value calculated by the total loss value calculation unit exceeds a predetermined threshold value (53). The display unit may include a determination result display unit (63) for displaying a determination result of the threshold value determination unit.

  In the optical pulse test apparatus according to the present invention, the display unit may include a marker display unit (61) for displaying a marker at the light level of the return light at the input / output terminal.

  In the optical pulse test apparatus according to the present invention, the calculation unit uses the light level of the second return light received by the light receiving unit to determine the light level at the incident end of the second pulsed light of the optical fiber to be measured. A connection loss value calculation unit (54) for calculating a connection loss value between the dummy fiber and the measured optical fiber using the calculated light level and the light level of the return light at the input / output end. You may have.

  In the optical pulse test apparatus of the present invention, the display unit may include a connection loss value display unit (64) for displaying a connection loss value calculated by the connection loss value calculation unit.

  In the optical pulse test apparatus according to the present invention, the computing unit calculates the light level from the input / output port to a predetermined distance using the light level of the second return light received by the light receiving unit. A light level calculating section (55), wherein the display section displays a straight line connecting the light level of the second return light and the light level calculated by the input / output end vicinity light level calculating section; A level display unit (65) may be provided.

  The above inventions can be combined as much as possible.

  ADVANTAGE OF THE INVENTION According to this invention, the optical pulse test method and optical pulse test apparatus which can perform the OTDR measurement of a long-distance to-be-measured optical fiber accurately using a short dummy fiber can be provided.

1 shows an example of an optical pulse test apparatus according to a first embodiment. 2 shows an example of an optical pulse test method according to the first embodiment. An example of the light level of the 1st return light _PB1 is shown. An example of the light level of the 2nd return light _PB2 is shown. An example of the optical pulse test apparatus which concerns on Embodiment 2 is shown. An example of the optical pulse test method which concerns on Embodiment 2 is shown.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
FIG. 1 shows an example of an optical pulse test apparatus according to this embodiment. The optical pulse test apparatus 101 according to the present embodiment performs OTDR measurement by making the pulsed light _PF2 incident on the optical fiber 100 to be measured having a distance _DT and measuring the return light _PB2 from the optical fiber 100 to be measured. . The optical pulse test apparatus 101 includes a light source 11, an input / output port 12, a dummy fiber 13, a light receiving unit 14, a calculation unit 15-1, a display unit 16-1, a timing generation unit 17, an ADC (Analog). to Digital Converter) 18.

  The light source 11 outputs pulsed light. The timing generator 17 drives the light source 11 and changes the pulse width of the pulsed light. Moreover, the timing generation part 17 outputs the timing which the light source 11 output the pulsed light to the calculating part 15-1. Thereby, the calculating part 15-1 can measure the time after receiving pulsed light until receiving return light, and can calculate the distance by which pulsed light was scattered.

  The pulsed light from the light source 11 is output to the dummy fiber 13 via the optical coupler 19. The dummy fiber 13 guides the pulsed light from the light source 11 to the input / output port 12. The input / output port 12 can be connected to the optical fiber 100 to be measured. In a state where the measured optical fiber 100 is connected to the input / output port 12, the pulsed light from the light source 11 is scattered by the measured optical fiber 100 to generate return light, and the return light is input to the input / output port 12. Is done. The return light input to the input / output port 12 is output to the dummy fiber 13. The return light propagated through the dummy fiber 13 is output to the light receiving unit 14 via the optical coupler 19.

  The light receiving unit 14 receives the return light and detects the light level of the return light. The ADC 18 samples the light level from the light receiving unit 14 and converts it into a digital signal. The computing unit 15-1 performs computation using the light level of the return light received by the light receiving unit 14. The display unit 16 displays the calculation result of the calculation unit 15-1.

  FIG. 2 shows an example of an optical pulse test method according to this embodiment. The optical pulse test method according to the present embodiment includes a first measurement procedure S101, a second measurement procedure S102, an input / output end return light level calculation procedure S103, and a total loss value calculation procedure S111 in this order. The optical pulse test method according to the present embodiment further includes a total loss value display procedure S112, a threshold determination procedure S113, and a marker display procedure S121 after the total loss value calculation procedure S111. In the present embodiment, an example is shown in which the total loss value display procedure S112, the threshold value determination procedure S113, and the marker display procedure S121 are performed simultaneously after the total loss value calculation procedure S111, but these procedures may be performed in any order. Good.

In the first measurement procedure S101, and enters the first pulse light _{P F1} to the dummy fiber 13, measuring the light level of the first return beam _{P B1} to the first pulse light _{P F1} is scattered by the dummy fiber 13 To do. Here, the first pulsed light P _F1 has a first pulse width in which the dead zone is equal to or shorter than the time corresponding to the length of the dummy fiber 13. Thereby, even when the dummy fiber 13 is short, the light level of the first return light P _B1 at the input / output end can be measured. Here, the input / output end is an end of the dummy fiber 13 on the side to which the measured optical fiber 100 is connected.

For example, the optical fiber 100 to be measured is connected to the input / output port 12. In this state, the light source 11 outputs a first pulse light _{P F1.} The pulsed light _PF1 is scattered by the dummy fiber 13 and the measured optical fiber 100, and the first return light _PB1 is generated. The light receiving unit 14 receives the first return light P _B1 .

FIG. 3 shows an example of the light level of the first return light P _B1 . Due to the use of the first pulse light P _F1 having a first pulse width, even if the dummy fiber 13 is short, measures the light level L ₀ of the back scattered light at the output end of the dummy fiber 13 can do. However, the first pulse light P _F1, there is a case that sufficient performance is obtained for measuring the total length of the optical fiber under test 100. For this reason, the following second measurement procedure S102 is executed.

In the second measurement procedure S102, the second pulsed light _PF2 is incident on the dummy fiber 13 in a state where the measured optical fiber 100 is connected to the dummy fiber 13, and the second pulsed light _PF2 The light level of the second return light _PF2 scattered by the measured optical fiber 100 is measured. Here, the second pulse light P _F2 has a second pulse width that is wider than the first pulse width of the first pulse light P _F1 .

For example, the light source 11 outputs the pulsed light _PF2 in a state where the measured optical fiber 100 is connected to the input / output port 12. The pulsed light _PF2 is scattered by the dummy fiber 13 and is also scattered by the measured optical fiber 100 to generate return light _PB2 . The light receiving unit 14 receives the second return light P _{B2 in} which the pulsed light _PF2 is scattered by the dummy fiber 13 and the measured optical fiber 100.

FIG. 4 shows an example of the light level of the second return light _PB2 . A second light level of the return light _{P B2} at a distance _{D 1} of the from output port 12 is _{L 1,} a second light level of the return light _{P B2} to definitive distance _{D 2} from the input and output ports 12 by _{L 2} There, a second light level of the return light _{P B2} to definitive distance _{D T} from input-output port 12 is _{L T.} Because the second pulse width is wide, a second pulse light P _F2 light level L _0H of the scattered output end of the return beam with a dummy fiber 13 of the light level of the second return beam P _B2 is Cannot be identified because it is buried in the pulse waveform. Further, the light level L _0L of the second return beam P _B2 at the point where incident on the measured optical fiber 100 of the light level of the second return beam P _B2 is also unable to determine buried among the pulse waveform. Therefore, the input / output terminal return light level calculation procedure S103 is executed.

In the input and output terminals return light level calculation procedure S103, the input and output terminals return light level calculator 51 of the calculation unit 15-1, a second pulse light P _F2 of the light level of the second return beam P _B2 dummy The light level L _0H of the return light at the input / output end scattered by the fiber 13 is calculated.

For example, input and output terminals return light level calculator 51 of the calculation unit 15-1, by using the first pulse width and the second pulse width, the second pulse light to the optical power of the first pulse light P _F1 calculating the ratio of the optical power of P _F2. Then, the input / output terminal return light level calculation unit 51 adds this ratio to the light level of the first return light P _B1 at the input / output terminal . Thereby, the input / output end return light level calculation unit 51 can calculate the light level L _0H of the input / output end return light in which the second pulsed light _PF2 is scattered by the dummy fiber 13 .

In total loss value calculation procedure S111, the total loss value calculation unit 52 of the arithmetic unit 15-1, the light level _{L T} and the input-output terminal level of the reflecting light of the second return beam _{P B2} measured in the second measurement procedure S102 The light loss value ΔL _T in the measured optical fiber 100 is calculated using the light level L _0H of the return light at the input / output end calculated in the calculation procedure S103. For example, to calculate the difference between the light level _{L T} and the light level _{L 0H.}

In total loss value display procedure S112, the total loss value display unit 62 of the display unit 16-1 displays the loss value [Delta] L _T of light in the optical fiber to be measured 100, which is calculated by the total loss value calculation procedure S111.

In the threshold determination procedure S113, it determines whether the loss value [Delta] L _T of the light calculated in the total loss value calculation procedure S111 exceeds a predetermined threshold, to display the determination result.

For example, an arbitrary threshold value is set in the calculation unit 15-1. The threshold judging unit 53 of the arithmetic unit 15-1, the loss value [Delta] L _T to calculate the total loss value calculation unit 52 determines whether or not exceeds the threshold value. The determination result display unit 63 of the display unit 16-1 displays the determination result of the threshold value determination unit 53. As a result, it is possible to quickly determine whether or not the optical fiber 100 to be measured has no obstacle when the optical line is opened.

In the marker display procedure S121, the marker display unit 61 of the display unit 16-1 displays a marker at the light level L _0H of the input / output terminal return light calculated in the input / output terminal return light level calculation procedure S103.

(Embodiment 2)
FIG. 5 shows an example of an optical pulse test apparatus according to this embodiment. The optical pulse test apparatus 102 according to the present embodiment includes a calculation unit 15-2 and a display unit 16-2 instead of the calculation unit 15-1 and the display unit 16-1 described in the first embodiment.

  FIG. 6 shows an example of an optical pulse test method according to the second embodiment. The optical pulse test method according to the present embodiment includes a measured optical fiber incident light level calculation procedure S131, a connection loss value calculation procedure S132, and a connection after the input / output end return light level calculation procedure S103 described in the first embodiment. It includes a loss value display procedure S133 and a second return light estimation straight line display procedure S134.

In optical fiber to be measured incident light level calculation procedure S131, by using the light level of the second return beam P _B2 measured in the second measurement procedure S102, enters the second pulse light P _F2 of the optical fiber under test 100 The light level of the second return light P _B2 at the end is calculated.

At this time, the connection loss value calculation unit 54 of the calculation unit 15-2 calculates the light level _L0L at the input / output port 12 using the light level of the second return light _PB2 received by the light receiving unit 14. For example, the distance by using a straight line passing through the light level _{L 2} in light level _{L 1} and the distance _{D 2} in _{D 1,} and calculates the light level _{L 0L} at the incident end of the optical fiber under test 100.

In connection loss value calculation procedure S132, by using the light level L _0L calculated in light level L _0H and the measured optical fiber the incident light level calculation procedure S131 calculated in input and output ends returning light level calculation procedure S103, the dummy fiber 13 A connection loss value ΔL ₀ with the optical fiber 100 to be measured is calculated.

At this time, the connection loss value calculation unit 54 of the calculation unit 15-2 uses the calculated light level L _0L at the input / output port 12 and the light level L _0H of the return light at the input / output end to connect the input / output port 12. Calculate the loss value. For example, the light level L _0L is subtracted from the light level L _0H .

  In the connection loss value display procedure S133, the connection loss value calculated in the connection loss value calculation procedure S132 is displayed. For example, the connection loss value display unit 64 of the display unit 16-2 displays the connection loss value calculated by the connection loss value calculation unit 54.

In the second return beam estimation linear display procedure S134, a straight line connecting the light level calculated by the second measurement procedure second return light level and the measured optical fiber the incident light level calculation procedure S131 of P _B2 measured at S102 (Reference numeral 91 in FIG. 4) is displayed.

At this time, the input / output end vicinity light level calculation unit 55 of the calculation unit 15-2 uses the light level of the second return light _PB2 received by the light receiving unit 14 to obtain a light level from the input / output port 12 to a predetermined distance. Is calculated. For example, using a line passing through the light level L ₂ in light level L ₁ and the distance D ₂ at a distance D _1, and calculates the light level from the output port 12 to the distance D _1. Although the predetermined distance is arbitrary, for example, it is the distance D ₁ at which the light level of the second return light P _B2 is clear. The input / output end vicinity light level display unit 65 displays the light level calculated by the input / output end vicinity light level calculation unit 55.

  The optical pulse test apparatus 102 according to the present embodiment may be combined with the optical pulse test apparatus 101 according to the first embodiment. For example, the calculation unit 15-2 may further include an input / output terminal return light level calculation unit 51, a total loss value calculation unit 52, and a threshold value determination unit 53 illustrated in FIG. In this case, the display unit 16-2 further includes the marker display unit 61, the total loss value display unit 62, and the determination result display unit 63 illustrated in FIG.

  Further, the optical pulse test method according to the present embodiment may be combined with the optical pulse test method according to the first embodiment. For example, the optical pulse test method according to the present embodiment may further execute the total loss value calculation procedure S111, the total loss value display procedure S112, the threshold value determination procedure S113, and the marker display procedure S121 shown in FIG.

  The present invention can be applied to the information communication industry.

11: Light source 12: Input / output port 13: Dummy fiber 14: Light receiving unit 15-1, 15-2: Calculation unit 16-1, 16-2: Display unit 17: Timing generation unit 18: ADC
19: Optical coupler 51: Input / output end return light level calculation unit 52: Total loss value calculation unit 53: Threshold value determination unit 54: Connection loss value calculation unit 55: Input / output end vicinity light level calculation unit 61: Marker display unit 62: Total loss value display unit 63: Determination result display unit 64: Connection loss value display unit 65: Light level display unit near input / output terminal 100: Optical fiber 101 to be measured 101, 102: Optical pulse test apparatus

Claims (16)

A first pulse light having a first pulse width that makes a dead zone equal to or less than a time corresponding to the length of the dummy fiber is incident on the dummy fiber, and the first pulse light is scattered by the dummy fiber. A first measurement procedure (S101) for measuring the light level of the return light;
In a state where the optical fiber to be measured is connected to the dummy fiber, the second pulse light having a second pulse width wider than the first pulse width is incident on the dummy fiber, and the second fiber A second measurement procedure (S102) for measuring the light level of the second return light in which the pulsed light is scattered by the dummy fiber and the measured optical fiber;
Using the first pulse width, the second pulse width, and the light level of the first return light, the second pulse light of the light level of the second return light is the dummy fiber. An input / output end return light level calculation procedure (S103) for calculating the light level of the return light at the input / output end that is the end of the dummy fiber on the side to which the scattered optical fiber to be measured is connected;
An optical pulse test method comprising: Using the light level of the second return light measured in the second measurement procedure and the light level of the return light of the input / output end calculated in the input / output end return light level calculation procedure, The total loss value calculation procedure (S111) for calculating the light loss value of
The optical pulse test method according to claim 1, further comprising after the input / output terminal return light level calculation procedure. A total loss value display procedure (S112) for displaying a loss value of light in the measured optical fiber calculated in the total loss value calculation procedure;
The optical pulse test method according to claim 2, further comprising after the total loss value calculation procedure. It is determined whether or not the light loss value calculated in the total loss value calculation procedure exceeds a predetermined threshold value, and a threshold value determination procedure (S113) for displaying a determination result includes the total loss value. The optical pulse test method according to claim 2, further comprising a value calculation procedure. A marker display procedure (S121) for displaying a marker on the light level of the return light at the input / output end calculated in the input / output end return light level calculation procedure;
5. The optical pulse test method according to claim 1, further comprising after the input / output end return light level calculation procedure. Using the light level of the second return light measured in the second measurement procedure, the light level of the second return light at the incident end of the second pulsed light of the optical fiber to be measured is calculated. A measured optical fiber incident light level calculation procedure (S131) is further provided after the second measurement procedure,
A connection loss value between the dummy fiber and the measured optical fiber using the light level calculated in the input / output end return light level calculation procedure and the optical level calculated in the measured optical fiber incident light level calculation procedure. 6. The optical pulse test method according to claim 1, further comprising: a connection loss value calculation procedure (S <b> 132) for calculating the I / O terminal return light level calculation procedure. The optical pulse test according to claim 6, further comprising a connection loss value display procedure (S133) for displaying the connection loss value calculated in the connection loss value calculation procedure after the connection loss value calculation procedure. Method. Second return light estimated straight line display procedure (S134) for displaying a straight line connecting the light level of the second return light measured in the second measurement procedure and the light level calculated in the measured optical fiber incident light level calculation procedure (S134) The optical pulse test method according to claim 6, further comprising: after the input / output terminal return light level calculation procedure. A light source (11) for outputting pulsed light;
An input / output port (12) connectable to the optical fiber to be measured (100);
A dummy fiber (13) connected to the input / output port for outputting pulsed light from the light source to the optical fiber to be measured connected to the input / output port;
A light receiving unit (14) for receiving the first return light in which the pulsed light is scattered by the dummy fiber or the second return light in which the pulsed light is scattered by the dummy fiber and the measured optical fiber;
A calculation unit (15) that performs calculation using the light levels of the first return light and the second return light received by the light receiving unit;
A display unit (16) for displaying a calculation result of the calculation unit;
With
The light source outputs a first pulse light having a first pulse width in which a dead zone is equal to or less than a time corresponding to the length of the dummy fiber, and a second pulse having a pulse width wider than the first pulse width. Outputting a second pulse light having a pulse width;
The light receiving unit receives the first return light in which the first pulsed light is scattered by the dummy fiber, and the second pulsed light is scattered by the dummy fiber and the measured optical fiber. Receiving the return light of 2,
The computing unit uses the first pulse width, the second pulse width, and the light level of the first return light received by the light receiving unit, and out of the light levels of the second return light. The input / output end return light level for calculating the light level of the return light at the input / output end, which is the end of the dummy fiber on the side to which the measured optical fiber is connected, the second pulsed light being scattered by the dummy fiber An optical pulse test apparatus comprising a calculation unit (51).   The arithmetic unit uses the light level of the second return light and the light level of the return light at the input / output end to calculate a total loss value for calculating the loss value of the second pulsed light in the measured optical fiber. The optical pulse test apparatus according to claim 9, further comprising a calculation unit (52).   The optical pulse test apparatus according to claim 9 or 10, wherein the display unit further comprises a total loss value display unit (62) for displaying a loss value calculated by the total loss value calculation unit. The calculation unit includes a threshold value determination unit (53) for determining whether or not the loss value calculated by the total loss value calculation unit exceeds a predetermined threshold value.
The optical pulse testing device according to claim 10 or 11, wherein the display unit includes a determination result display unit (63) for displaying a determination result of the threshold value determination unit.   The optical pulse test apparatus according to any one of claims 9 to 11, wherein the display unit includes a marker display unit (61) for displaying a marker at the light level of the return light at the input / output terminal.   The calculation unit calculates a light level at an incident end of the second pulsed light of the optical fiber to be measured using a light level of the second return light received by the light receiving unit, and calculates the calculated light level and The connection loss value calculation unit (54) for calculating a connection loss value between the dummy fiber and the optical fiber to be measured using an optical level of return light at the input / output end. To 13. The optical pulse test apparatus according to any one of 1 to 13.   15. The optical pulse testing device according to claim 14, wherein the display unit includes a connection loss value display unit (64) for displaying a connection loss value calculated by the connection loss value calculation unit. The calculation unit includes an input / output end vicinity light level calculation unit (55) that calculates a light level from the input / output port to a predetermined distance using the light level of the second return light received by the light receiving unit. ,
The display section includes an input / output end near light level display section (65) for displaying a straight line connecting the light level of the second return light and the light level calculated by the input / output end vicinity light level calculation section. The optical pulse test apparatus according to claim 9, wherein the optical pulse test apparatus is characterized in that

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