JP5298043B2 - Optical cable laying environment measuring method, optical cable laying environment measuring device, and optical cable laying environment measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine whether an optical cable at a reflective area such as a connecting point, is overhead or underground, without using a facility database. <P>SOLUTION: A laying environment measuring device 22 by B-OTDR or R-OTDR is optically connected by using an optical coupler 13 upstream of optical cables 14, 16 to be measured. The measuring device 22 compares and determines changes of temperature in the longitudinal directions of the optical cables 14, 16 obtained by measurement by B-OTDR or R-OTDR with a threshold set depending on environmental property, and the device identifies 'underground' or 'overhead', based on a temperature change width. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an optical cable installation environment measuring method for identifying whether an optical cable installation environment is underground or aerial, and an apparatus and system thereof for maintenance and operation of an optical fiber communication network.

  In the maintenance and operation of optical fiber communication networks, accurate and fresh measurement information is required for the environmental management of optical equipment constituting the communication network. In particular, it is important to identify whether it is underground or fictitious because the skills required of workers differ depending on the installation environment of optical cables.

  An optical cable laying environment measurement method using a conventional optical equipment identification method (for example, see Patent Document 1) will be described. First, the distance loss measurement of the target optical line is performed using an OTDR (Optical Time Domain Reflectometry) method, which is a standard optical evaluation method for optical fiber communication networks.

  FIG. 11 is a diagram showing a configuration of an optical communication line facility measured using a conventional OTDR method. In FIG. 11, an OLT (in-house device) 11 is an ONU (line terminator) through an in-house optical wiring 12, an optical coupler 13, an underground cable 14, a first closure 15, an aerial cable 16, a second closure 17, and a filter 18. It is assumed that an optical communication line is established between the OLT 11 and the ONU 19.

  When performing maintenance and operation on the optical equipment of this optical communication line, the OTDR test apparatus 20 is coupled at the optical coupler 13 that optically connects the in-house optical wiring 12 and the underground cable 14. The OTDR test apparatus 20 includes a test light transmitter 201, a test light detector 202, an optical coupler 203, and a PC control unit 204.

  The test light transmitter 201 generates a laser having a wavelength of 1.65 μm and transmits it as test light. This test light is sent from the optical coupler 13 of the optical communication line to the underground cable 14 via the optical coupler 203 for maintenance. Optical transmission is performed using a wavelength (U-band). However, since the filter 18 that blocks the test light is installed in front of the communication light detector of the ONU 19, only the communication light is transmitted to the ONU 19. Therefore, even during the test, an in-service optical test can be performed for the communication light of 1.26 μm to 1.625 μm.

  The test light transmitted from the test light transmitter 201 propagates through the optical couplers 203 and 13 while being backscattered through the underground cable 14 and the overhead cable 16. The backscattered light from the underground cable 14 and the overhead cable 16 passes through the optical couplers 13 and 203 and is photoelectrically converted by the test light detector 202. The detection signal photoelectrically converted by the test light detector 202 is plotted as a backscattered light intensity with respect to the distance in the longitudinal direction of the underground cable 14 and the aerial cable 16 by the PC control unit 204 to form a graph. The above is the OTDR method.

  Next, a conventional method for identifying an optical facility from a result measured using the OTDR method will be described. FIG. 12 shows an example of a waveform observed by the OTDR method. As shown in FIG. 12, the reflection a and the loss b are due to connectors and fusion points existing in the underground cable 14 and the overhead cable 16, respectively.

  In order to manage the optical equipment based on the above observation results, an equipment database as shown in Table 1 is constructed in advance.

例えば、反射ａや損失ｂの光設備を特定するために設備データベースを用いて、コネクタや融着点の位置とＯＴＤＲ波形を比較照合する。ここで、１ｋｍ地点に反射ａを観測した時は、前記設備データベースの１ｋｍ地点の光設備を確認する。

For example, the facility database is used to identify the optical equipment having the reflection a and the loss b, and the position of the connector or the fusion point is compared with the OTDR waveform. Here, when the reflection a is observed at the 1 km point, the optical equipment at the 1 km point in the equipment database is confirmed.

  If it is recorded as connector and underground in the equipment database, it can be understood that the reflection a is due to connector connection in the underground closure. Here, since the underground cable is connected to the underground closure, the optical line up to the reflection a can be analogized with the underground cable. Similarly, the loss b can be identified as a fusion splice in the aerial closure, and it can be inferred that an aerial cable is laid up to the loss b.

Japanese Patent Publication No. 7-28266

H. Izumita, T. Horiguchi, and T. Kurashima, in Optical Fiber Sensors, OSA Technical Digest Series, paper OWD1 (1997). G. Bolognini, J. Park, A. Chiuchiarelli, N. Park, and F. Di Pasquale, in Optical Fiber Sensors, OSA Technical Digest, p. ThE45 (2006). D.K.Gifford, B.J.Soller, M.S.Wolfe and M.E.Froggatt, Optical Communication vol. 3, p. 511-512 (2005).

  However, in the conventional optical equipment identification method using the OTDR method, an equipment database of connection points is necessary to specify the optical cable laying environment. If the equipment database is not referred to, the underground / aerial environment can be inferred. Can not. In addition, an error may occur in the measurement result due to the difference between the length of the optical cable and the actual length, and it may be difficult to detect the cable connection point at the low-loss fusion point. Furthermore, in the equipment database, there is a problem that an OTDR measurement result and a database collation error occur due to data not updated due to a human error or a data input error. Thereby, there is a problem that accurate and fresh information management of the optical equipment is difficult. In addition, conventionally, in order to perform optical equipment identification, it is necessary to construct an equipment database in advance. Further, when the equipment position is changed in the maintenance work of the optical equipment, database update work occurs, and the work volume increases.

  The present invention has been made in view of the above circumstances, and an optical cable installation environment measuring method capable of automatically identifying in-service underground / aerial as an optical cable installation environment by an optical method without using an equipment database. An object of the present invention is to provide an apparatus and a system thereof.

The optical cable laying environment measuring method according to the present invention has the following configuration.
(1) In an optical cable laying environment measuring method for identifying whether an optical cable laying environment in an optical line constituting an optical fiber communication network is underground or aerial, test light is transmitted to the optical cable and is generated by the test light in the optical cable Taking back-scattered light, receiving the back-scattered light, measuring the change in the optical component of the scattered light in the longitudinal direction of the optical cable, obtaining the temperature in the optical cable from the change in the optical component, from the time change of the temperature A temperature change width is measured, and an aspect in which underground or aerial is identified from the temperature change width is set.

(2) In (1), the measurement of the temperature change width is an aspect in which the difference between the highest temperature and the lowest temperature of the day is the temperature change width.
(3) In (2), if the temperature change width is less than 2 degrees, it is determined as an underground environment, and if it is 2 degrees or more, it is determined as an aerial environment.
(4) In (1), the temperature change with time is measured by receiving Brillouin scattered light generated in the optical cable and analyzing the Brillouin scattered light and frequency.

(5) In (1), the time change of the temperature is measured by receiving Raman scattered light generated in the optical cable, analyzing the intensity change, and measuring the temperature.
(6) In (1), the temperature change width measurement period is 1 hour, and if the temperature change width is less than 1 degree, it is determined as an underground environment, and if it is 1 degree or more, it is determined as an aerial environment.

  (7) In an optical cable installation environment measuring method for identifying whether an optical cable installation environment using an optical fiber in an optical line constituting an optical fiber communication network is underground or aerial, the test light is multiplexed and demultiplexed, and the test light A reference fiber having a constant environmental temperature is interposed in the optical line for transmitting the optical fiber, test light is transmitted to the optical coupler, backscattered light generated in the optical fiber is received, and the absolute temperature is Calculation is performed and the absolute temperature is compared with a preset underground temperature range to identify whether it is underground or aerial.

(8) In (7), the absolute temperature is measured a plurality of times, and if the absolute temperature is included in the underground temperature range, the underground environment is determined.
(9) In (7), the absolute temperature is measured a plurality of times, and if the absolute temperature is included outside the underground temperature range, it is determined as an aerial environment.

The optical cable laying environment measuring apparatus according to the present invention has the following configuration.
(10) In an optical cable laying environment measuring device for identifying whether an optical cable laying environment in an optical line constituting an optical fiber communication network is underground or aerial, a test light is transmitted to the optical cable, a light source that generates test light, Optical means for receiving and receiving backscattered light generated by the test light in the optical cable, and measuring the change in the optical component of the scattered light in the longitudinal direction of the optical cable from the received light signal of the backscattered light, and changing the optical component Measuring means for determining the temperature in the optical cable from the temperature, measuring the temperature change width from the time change of the temperature, and identifying means for identifying underground or aerial from the change width of the temperature change obtained by the measurement means Let it be an aspect.

  (11) In an optical cable laying environment measuring apparatus for identifying whether an optical cable laying environment using an optical fiber in an optical line constituting an optical fiber communication network is underground or aerial, a light source that generates test light; Optical means for transmitting and receiving backscattered light generated by the test light in the optical fiber; measuring means for measuring a temporal change in temperature in the longitudinal direction of the optical cable from the received light signal of the backscattered light; and the test The absolute temperature is calculated from the position of the reference fiber that is interposed in the optical line that sends out the light and the environment temperature is constant. By comparing the absolute temperature with the preset underground temperature range, it can be determined whether it is underground or aerial. And an identification means for identifying the device.

The optical cable laying environment measurement system according to the present invention is configured as follows.
(12) A measurement device that performs the optical cable laying environment measurement method according to (1) or (7), and controls the measurement device from a remote location through a communication network to determine the underground or aerial laying environment of the optical cable. It is set as the aspect which comprises a communication terminal device which acquires.

  As described above, according to the present invention, the installation environment of an optical cable is automatically determined without using an equipment database in an existing optical line composed of a plurality of optical cables without using a special optical cable. be able to. As a result, the optical cable laying environment can be used to measure the temporal change in temperature in the longitudinal direction of the optical cable using an optical method without using an equipment database, and to automatically distinguish between underground and aerial from the size of the change width in-service. A measurement method, an apparatus thereof, and a system can be provided.

1 is a configuration diagram and waveform diagram of an optical communication line facility to which an optical cable laying environment measuring method according to a first embodiment of the present invention is applied. In the said 1st Embodiment, the figure which illustrates the temperature change of the underground and the fictitious one day. The figure which shows the specific structure of the optical cable-laying environment measuring apparatus in the installation shown in FIG. 1 as 2nd Embodiment which concerns on this invention. The flowchart which shows the flow of the process in the method of the said 2nd Embodiment. The figure which illustrates the temperature change of the underground and the fictitious day for demonstrating the method to shorten test time as 3rd Embodiment which concerns on this invention. The flowchart which shows the flow of a process in the method of the said 3rd Embodiment. The block diagram and waveform diagram of the optical communication line equipment to which another optical cable laying environment measuring method is applied as the fourth embodiment according to the present invention. The flowchart which shows the flow of a process in the method of the said 4th Embodiment. The block diagram of the optical-communications line equipment in the case of implementing optical cable laying environment measurement by remote control as 5th Embodiment concerning this invention. The flowchart which shows the flow of a process in the method of the said 5th Embodiment. The figure which shows the structure of the optical communication line equipment measured using the conventional OTDR method. The figure which shows an example of the waveform observed by the OTDR method.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 shows an optical communication line facility to which the optical cable laying environment measuring method according to the first embodiment of the present invention is applied. (A) is a block diagram showing the equipment configuration, and (b) is shown in (a). In the equipment shown, it is a waveform diagram showing the relationship between the distance from entering the underground until reaching the ONU 19 and the absolute temperature.

  In FIG. 1, the optical communication line equipment is similar to the configuration shown in FIG. 11, in which an OLT (in-house device) 11 includes an in-house optical wiring 12, an optical coupler 13, an underground cable 14, a first closure 15, an aerial cable 16, It is assumed that an optical communication line is established between the OLT 11 and the ONU 19 by optically connecting to the ONU (line termination unit) 19 via the two closures 17 and the filter 18. Each of the underground cable 14 and the aerial cable 16 is an optical cable in which a plurality of optical fiber cores are bundled in an optical line constituting an optical fiber communication network.

  When performing maintenance / operation on this optical communication line facility, the cable laying environment measuring device 22 according to the present invention is coupled to the optical coupler 13 that optically connects the in-house optical wiring 12 and the underground cable 14. The measuring device 22 enters test light into the core of the optical fiber to be measured via the optical coupler 13 and detects backscattered light generated by the test light propagating through the core of the optical fiber.

  In the above configuration, in the optical cable laying environment measuring method according to the first embodiment of the present invention, the optical cable laying environment measuring device 22 is installed in advance upstream of the underground cable 14 and the aerial cable 16 for measuring the laying environment. Test light is incident through the coupler 13. The backscattered light generated by the test light propagating through the optical fiber is detected by the optical cable laying environment measuring device 22.

  Here, FIG. 2 shows an example of the daily outside air and underground temperature. The daily temperature change of the outside air is larger than the underground temperature change. From this, by measuring the absolute value of the temporal change in temperature in the longitudinal direction of the optical cable, it is possible to measure the laying environment of the optical cable without using the equipment database.

Further, the measurement method is not limited to a sensing cable specialized for temperature measurement. The present invention can also be applied to an existing optical fiber cable for communication or an optical fiber communication network composed of a plurality of types of optical cables.
(Second Embodiment)
Next, as an example of determining an optical cable laying environment, a method according to a second embodiment for measuring a temperature change from a frequency shift of Brillouin scattered light will be described.

As an example of the optical cable laying environment measuring device 22, FIG. 3 shows a specific configuration when a Brillouin scattered light pulse tester (B-OTDR) is used.
In FIG. 3, continuous light having a frequency ν ₀ emitted from the test light source 221 is branched at the mouth by the optical coupler 222 and divided into local light and test light. The test light is pulsed by the optical switch 223 and then incident on the measured optical fiber in the optical communication line via the optical coupler 224.

In the measured fiber, Brillouin backscattered light having a frequency shift ν _B is generated by the incident test light. The Brillouin backscattered light returns to the measuring device 22, is combined with local light having an optical frequency ν _{0 by} the optical coupler 225 in the measuring device, and is received as a beat signal ν _B by the light receiving element (PD) 226. . The beat signal obtained by the light receiving element 226 is amplified by an amplifier 227 and further mixed by a mixer 229 with a frequency signal from a local oscillator (LO) 228 that generates a frequency signal close to the beat signal ν _B and converted into a baseband signal. Is done. From the baseband signal, other high-frequency signals are removed by a low-pass filter (LPF) 22a, whereby the intensity of the Brillouin scattered light signal frequency-shifted ν _B is obtained. The intensity signal is converted into a digital signal by the A / D converter 22b and output to the identification processing device 22c as a measurement result.

  The identification processing device 22c obtains the distance L from the B-OTDR with respect to the time t when the scattered light returns by L = 1/2 (v · t) (v: speed of light in the fiber). Here, the frequency shift varies depending on the temperature of the environment where the underground cable 14 and the overhead cable 16 are laid.

  The details of this temperature change are described in Non-Patent Document 1. According to the explanation, the frequency of the Brillouin backscattered light has a property of changing by about +1.08 MHz with respect to the change of the temperature of the optical fiber by 1 degree. Using this description, the frequency shift is converted into a temperature change, and the temperature change in the cable longitudinal direction can be measured. FIG. 1B shows a profile in the longitudinal direction of the optical cable in which the Brillouin scattering frequency change is measured every 1 hour per day and the maximum change is converted into a temperature change.

  Here, from FIG. 2, when the threshold value of the underground environment is set to be less than 2 degrees, the optical cable portion whose daily temperature change is 0.7 degrees can be determined as the underground environment. Further, when the threshold value of the fictional environment is set to 2 degrees or more, the optical cable portion whose daily temperature change is 3.3 degrees can be determined as the fictional environment. Therefore, if the dotted line in FIG. 1 is a threshold value, it can be determined that 0 to L are underground and L to are imaginary.

The process flow of the above method will be described with reference to the flowchart shown in FIG.
In FIG. 4, first, test light is incident on the optical cable to be measured, the Brillouin frequency shift of the Brillouin scattered light that is return light is converted into temperature, and a temperature distribution graph in the longitudinal direction of the optical cable is created (step S11). The measurement data obtained at this time is sequentially stored (step S12).

Here, the measurement time from the start of measurement is measured (step S13). When the measurement time is less than one day, the process returns to step S11, and when it is more than one day, the maximum temperature and the minimum temperature for each distance of the optical cable. The daily temperature change is calculated from the difference between the two (step S14).
Next, the temperature change obtained in step S14 is compared with a preset threshold value (step S15). If the temperature change is less than the threshold value, the cable laying environment is determined to be underground (step S16). Is greater than or equal to the threshold value, it is determined that the environment is fictitious (step S17).

Next, determination of step S15 is performed for every cable longitudinal direction, and an underground environment or an aerial environment is displayed (step S19). It is determined whether all determinations in the cable longitudinal direction have been made (step S20). If all the determinations have been made, a series of processing ends.
The above is an example in which the optical cable laying environment temperature is measured from the frequency of Brillouin scattered light by B-OTDR, but R-OTDR that can measure the temperature change from the signal intensity change of Raman scattered light can also be used as an optical cable laying environment measuring apparatus. .

Note that the Raman scattered light has components of Stokes scattered light and anti-Stokes scattered light, and it is described in Non-Patent Document 2 that the ratio of anti-Stokes light to Rayleigh scattered light intensity changes once by 0.65%. Has been.
Moreover, OFDR that can measure temperature change from frequency change of Rayleigh scattered light can also be used as an optical cable laying environment measuring device. Non-Patent Document 2 describes that the Rayleigh scattered light changes once per 10 pm wavelength change.

(Third embodiment)
In the first and second embodiments, a continuous test of at least 24 hours or more is required in order to measure the optical cable installation environment from the outside air temperature and the underground temperature of the optical communication line (optical line) and the temperature change of the underground temperature for one day. . Hereinafter, a method for shortening the test time will be described as a third embodiment.

  FIG. 5 shows the temperature change in one day in the installation environment of the optical communication line (optical line) in the same manner as in FIG. In this example, the threshold is set to 1 degree, and the temperature laying for 1 hour in a time zone in which the temperature change of the outside air during the day is large is measured and tested. . In this example, the change in the underground temperature is about 0.7 degrees and does not exceed the threshold, whereas the change in the outside air temperature is 1 degree or more in one hour during a certain daytime. Become. Therefore, by selecting a time zone, measuring a temperature change for one hour, and comparing it with a threshold value of 1 degree, it is possible to easily identify whether it is fictitious or underground, and it is possible to reduce the test time.

The processing flow of the above method will be described with reference to the flowchart shown in FIG.
In FIG. 6, first, test light is incident on the optical cable to be measured, the Brillouin frequency shift of the Brillouin scattered light that is the return light is converted into temperature, and a temperature distribution graph in the longitudinal direction of the optical cable is created (step S21). The measurement data obtained at this time is sequentially stored (step S22).

  Here, it is determined whether the measurement time is less than one hour after the start of measurement (step S23). If less than one hour, the process returns to step S21. If it is one hour or more, the temperature for one hour for each distance of the optical cable. The change is calculated, and the cable location where the change width of the temperature change is 1 degree or more is determined as an aerial environment (the cable location less than 1 degree is the underground environment) (step S24), and all the cable longitudinal directions are determined. Then exit.

(Fourth embodiment)
Next, a method according to a fourth embodiment for measuring the optical cable installation environment from the absolute temperature of the optical communication line (optical line) will be described.
FIG. 7A is a configuration diagram when the method of the fourth embodiment is applied to equipment having the same configuration as the optical communication line equipment shown in FIG. 1A, and FIG. In the installation shown to (a), it is a wave form diagram which shows the relationship between the distance from entering underground to reaching ONU19, and absolute temperature. In FIGS. 7A and 7B, the same parts as those in FIGS. 1A and 1B are denoted by the same reference numerals.

  Now, the temperature calibration cable 23 in which the temperature around the cable is kept constant is connected in advance to the optical cable at the mouth of the cable laying environment measuring device 22 to measure the frequency shift of the Brillouin scattered light in the longitudinal direction. The frequency shift is converted into a relative temperature using the conversion value described in the second embodiment (frequency shift +1.08 MHz and temperature 1 degree).

  Next, using the fact that the environmental temperature of the temperature calibration cable 23 is known, the relative temperature is calibrated to an absolute temperature. By measuring the optical cable twice and setting the absolute temperature range Tth of the underground environment in advance, as shown in FIG. 7B, if the two absolute temperatures are within the temperature range, decide. If one of the absolute temperatures is out of the temperature range, it is determined as an aerial environment.

  For example, when the temperature calibration cable is present at a temperature of 25 degrees and the frequency shift is 5.4 MHz, the relative temperature is 5 degrees using the converted value. From the above, it can be seen that there is a difference of 20 degrees between the relative temperature and the actual temperature, and the absolute temperature is obtained by adding 20 degrees to the relative temperature of the optical line. Here, when the temperature range 92 of the absolute temperature of the underground environment is set to 17 to 20 degrees, and the absolute temperatures measured at intervals of 2 hours are 19 degrees and 20 degrees, both are within the above temperature range. It is determined that there is an underground environment. Further, when the temperature is 19 degrees and 25 degrees, one exists outside the temperature range, so that it is determined as an aerial environment.

As described above, the absolute temperature for each distance in the longitudinal direction of the optical cable is measured twice and compared with the temperature range of the underground environment set in advance. But if it is out of range, it can be determined as a fictional environment.
Further, the number of times of measurement of the above method is not limited to two times, and may be measured a plurality of times.

The process flow of the above method will be described with reference to the flowchart shown in FIG.
In FIG. 8, first, test light is incident on the optical cable to be measured, the Brillouin frequency shift of the Brillouin scattered light that is the return light is converted into temperature, and the temperature converted from the Brillouin frequency shift of the optical cable that keeps the ambient temperature constant. The difference between the ambient temperatures is used as a temperature correction value, the absolute temperature is calculated by adding the temperature correction value to the measured temperature, and an absolute temperature distribution graph in the optical cable longitudinal direction is created (step S31).

  Next, two hours after the start of measurement, the same process of step S31 is performed again (step S32). Here, the underground and environment discrimination processing is performed from the absolute temperature measured twice (step S33). If even one of the temperatures is outside the preset underground temperature range, the installation environment of the optical cable is determined to be aerial. (Step S34) When both of the absolute temperatures are included in the underground temperature range, it is determined to be underground (step S35). If the determination is made, the installation environment in the longitudinal direction of the optical cable is identified as underground or aerial, and the process ends.

(Embodiment 5)
Furthermore, a method for an operator to identify the underground or aerial environment of an arbitrary cable using the optical cable laying environment measurement method shown in the second and fourth embodiments will be described with reference to FIG. . 9, the same parts as those shown in FIG. 1 are denoted by the same reference numerals, and different parts will be described here.

  In FIG. 9, an optical switch 31 for injecting test light into the selected optical cable is installed in advance between the optical cable laying environment measuring device 22 and the optical coupler 13. The optical switch 31 is connected to a communication terminal processing device 33 through a communication network (NW) 32, and can be switched and controlled so that test light is incident on an arbitrary optical cable from the device 33 by remote control.

  In the above configuration, the communication terminal processing device 33 executes the processing shown in FIG. In FIG. 10, when the operator instructs the start of the test, the optical cable number input standby state is entered (step S41), and when the operator designates the optical cable number, the optical cable of the designated number is connected through the communication network 32. The optical switch 31 is switched and controlled (step S42), the optical cable laying environment measuring device 22 is made to perform the measurement of the selected optical cable, and the measurement result sent from the measuring device 22 is in a standby state (step S43). When the measurement result is obtained by the measurement device 22 and sent through the communication network (NW) 32, the measurement result is received and displayed on the display device.

By adopting the method described above, the operator can remotely execute the optical cable laying environment measurement method.
The configuration of the present embodiment is an example, and the optical switch 31 may be installed as a separate device as appropriate.
Further, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

  Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different example embodiments may be combined as appropriate.

  DESCRIPTION OF SYMBOLS 11 ... OLT (In-house device), 12 ... In-house optical wiring, 13 ... Optical coupler, 14 ... Underground cable, 15 ... First closure, 16 ..., Second closure, 18 ... Filter, 19 ... ONU (Line termination device) 20 ... OTDR test apparatus, 201 ... Test light transmitter, 202 ... Test light detector, 203 ... Optical coupler, 204 ... PC controller, 22 ... Cable laying environment measuring device, 221 ... Test light source, 222 ... Optical coupler 223 ... Optical switch, 224 ... Optical coupler, 225 ... Optical coupler, 226 ... Light receiving element (PD), 227 ... Amplifier, 229 ... Mixer, 228 ... Local oscillator (LO), 22a ... Low pass filter (LPF), 22b ... A / D converter, 22c ... identification processing device, 23 ... temperature calibration cable, 31 ... optical switch, 32 ... communication network (NW), 33 ... communication End processing apparatus.

Claims (12)

In an optical cable laying environment measuring method for identifying whether an optical cable laying environment using an optical fiber in an optical line constituting an optical fiber communication network is underground or aerial,
Send test light to the optical cable,
Taking back scattered light caused by the test light in the optical cable;
Measure the change in the optical component of the scattered light in the longitudinal direction of the optical cable,
Obtain the temperature in the optical cable from the change of the optical component,
Measure the temperature change width from the time change of the temperature,
An optical cable laying environment measuring method, wherein underground or aerial is identified from a change width of the temperature change. The measurement of the temperature change width is as follows:
2. The optical cable laying environment measuring method according to claim 1, wherein a difference between the maximum temperature and the minimum temperature of the day is defined as a temperature change width.   The optical cable laying environment measuring method according to claim 2, wherein if the temperature change width is less than 2 degrees, it is determined as an underground environment, and if it is 2 degrees or more, it is determined as an aerial environment. The measurement of the temperature change over time is
2. The optical cable laying environment measuring method according to claim 1, wherein Brillouin scattered light generated in the optical cable is received, Brillouin scattered light and frequency are analyzed, and temperature is measured. The measurement of the temperature change over time is
The optical cable laying environment measuring method according to claim 1, wherein Raman scattered light generated in the optical cable is received, the intensity change is analyzed, and the temperature is measured. The measurement period of the temperature change width is 1 hour,
The optical cable laying environment measuring method according to claim 1, wherein if the temperature change width is less than 1 degree, it is determined as an underground environment, and if it is 1 degree or more, it is determined as an aerial environment. In an optical cable laying environment measuring method for identifying whether an optical cable laying environment using an optical fiber in an optical line constituting an optical fiber communication network is underground or aerial,
Test light is multiplexed / demultiplexed into the optical fiber,
A reference fiber having a constant environmental temperature is interposed in the optical line for transmitting the test light,
Test light is sent to the optical coupler,
Receiving backscattered light generated in the optical fiber;
Calculate the absolute temperature using the reference fiber,
An optical cable laying environment measurement method characterized by identifying whether it is underground or aerial by comparing the absolute temperature with a preset underground temperature range.   8. The optical cable laying environment measuring method according to claim 7, wherein the absolute temperature is measured a plurality of times, and if the absolute temperature is included in the underground temperature range, it is determined as an underground environment.   8. The optical cable laying environment measuring method according to claim 7, wherein the absolute temperature is measured a plurality of times, and if the absolute temperature is included outside the underground temperature range, it is determined as an aerial environment. In an optical cable laying environment measuring device for identifying whether the optical cable laying environment in an optical fiber constituting an optical fiber communication network is underground or aerial,
A light source for generating test light;
Optical means for transmitting test light to the optical cable, receiving back scattered light generated by the test light in the optical cable, and receiving light;
Measuring means for measuring the change in the optical component of the scattered light in the longitudinal direction of the optical cable, obtaining the temperature in the optical cable from the change in the optical component, and measuring the temperature change width from the time change in the temperature,
An optical cable laying environment measuring apparatus characterized by comprising identification means for identifying underground or aerial from the change width of the temperature change obtained by the measuring means. In an optical cable laying environment measuring device for identifying whether the optical cable laying environment in an optical fiber constituting an optical fiber communication network is underground or aerial,
A light source for generating test light;
Optical means for sending test light to the optical fiber and receiving backscattered light generated by the test light in the optical fiber;
Measuring means for measuring a temporal change in temperature in the longitudinal direction of the optical cable from the received light signal of the backscattered light;
The absolute temperature is calculated from the position of the reference fiber that is interposed in the optical line that transmits the test light, and the ambient temperature is constant, and the absolute temperature is compared with the preset underground temperature range. An optical cable laying environment measuring apparatus, characterized by comprising identification means for identifying whether it is fictitious. A measuring apparatus for performing the optical cable laying environment measuring method according to claim 1 or 7,
An optical cable laying environment measurement system comprising a communication terminal device for controlling the measurement device from a remote location through a communication network to determine the underground or aerial laying environment of the optical cable and acquiring the result.

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