KR20090100109A - The optical fiber monitoring apparatus and method using optical pulse pattern - Google Patents

Abstract

PURPOSE: An apparatus for monitoring an optical access network optical cable by using an optical pulse type and a method thereof are provided to update the normal state of the optical cable automatically although a change in an optical access network occurs. CONSTITUTION: An apparatus for monitoring an optical access network optical cable comprises a light incidence/extraction means(310), a light property measuring means(320) and an optical cable inspecting means(330). The light incidence/extraction means makes a test light incident to the optical cable and extracts the reflection light. The light property measuring means generates the test light and measures the pulse of the extracted reflection light. The optical cable inspecting means confirms the pulse type of the reflection light by comparing the pulse of the measured reflection light with a normal-state pulse which is previously measured.

Description

Optical fiber monitoring device using optical pulse type and its method {THE OPTICAL FIBER MONITORING APPARATUS AND METHOD USING OPTICAL PULSE PATTERN}

The present invention relates to an optical subscriber network optical cable monitoring apparatus using the optical pulse type and a method thereof, and more particularly to the reflected light by comparing the pulse of the reflected light measured in the optical subscriber network optical cable of the subscriber side with the measured normal pulse By checking the pulse type of and checking the failure status of the optical cable based on the pulse type of the reflected light, it is easy to check the failure status of the optical cable (for example, the failure, the failed cable and the predicted point of failure) and maintain The present invention relates to an optical network monitoring apparatus using optical pulse type and a method thereof, which can reduce installation cost.

Optical cable, an optical communication transmission medium, is a very important infrastructure in the high-speed information and communication society. The high-speed information communication network can be divided into a backbone network and a subscriber network. In particular, FTTH (Fiber To The Home) optical subscriber network, which is optical fiberization of subscriber network, uses optical fiber made of glass or plastic that is very thin from telephone company to home. Due to the widespread use of FTTH optical subscriber networks, the importance of optical cable monitoring technology for monitoring the status of optical cables and diagnosing fault conditions is increasing in FTTH optical subscriber networks consisting of optical cables from telephone stations to subscribers.

In this optical fiber monitoring technology, a typical device for measuring the failure state of the optical fiber is an optical time domain reflectometer (OTDR) measurement device. This OTDR measuring device analyzes the reflected light that is returned by injecting a light pulse into the optical fiber according to the distance distribution of the amount of light, and thus the distance to the loss connection point of the optical fiber and the loss of the connection loss and the amount of reflection from the connection point when the fiber is broken. Measure the distance, etc. Here, the reflected light refers to the reflection of light in a place where the refractive index of the optical fiber is nonuniform, and to return back to the light source direction. This OTDR measuring device is widely used as a measuring instrument for construction repair of optical cables. In addition, since the OTDR measuring device is relatively expensive as a device having high resolution, it is mainly used to inspect the condition of the optical fiber by carrying only the experts who professionally maintain the optical cable.

In general, the repair of the optical cable is repaired by the repair personnel to find the fault location of the optical cable through the customer's failure report. However, an optical cable failure that occurs when the subscriber modem is not operating or the optical communication cable for connecting the subscriber terminal to the network is not possible, so that failure detection by the communication equipment is impossible.

Conventionally, techniques for detecting the state of an optical cable using only an OTDR measuring device are applicable only to an optical cable network structure in which a transmission device and a transmission device transmit and receive one-to-one. Distinguish when there is a failure in another optical cable at a distance matching one end point in a network of multi-branch structures (e.g., B-PON / E-PON / G-PON / WDM-PON network structures) There is no prior art. In this case, you should rely only on the failure report of the subscriber. However, in a one-to-one Active Optical Network (AON), there is no need for a failure detection technology because there is a transmission / reception function between transmission equipments. However, the passive optical network (PON) has an optical cable structure in which a multi-branch (one N) exists between two equipments. Therefore, a failure state detection technology is required. There is a problem that there is no way to save.

Applying the conventional sensing technology limited to such simple one-to-one optical cable network to one-to-n star network structure (for example, B-PON / E-PON / G-PON / WDM-PON network structure) This is only possible if there is an additional device for monitoring the optical cable of the star network structure of 1 to n. Thus, the conventional monitoring technology using the OTDR measuring device has a problem that the applicability is very limited and additionally, many devices are required.

In addition, the conventional optical cable monitoring technology has a high cost and low efficiency structure because the hardware configuration of the system is complicated. This prior art is to be installed not only at the upper end but also at the lower end, so that the applicability is complicated and the maintenance cost of the FTTH subscriber network will increase. In addition, the conventional technology is difficult to secure the quality of the FTTH subscriber network can not meet the customer's expectations (company brand value), and the time and effort cost (operating cost) to understand or persuade the customer in the business will increase There is no problem.

Therefore, the prior art as described above does not monitor the failure state of the optical cable without an additional device for monitoring the optical fiber of the star network structure, and furthermore, there is a problem that maintenance costs or application is complicated, and to solve such problems It is a subject of the present invention.

Therefore, the present invention checks the pulse type of the reflected light by comparing the pulse of the reflected light measured in the optical subscriber network optical cable of the subscriber side with the pre-measured steady state pulse and examines the fault condition of the optical cable based on the pulse type of the reflected light. The optical fiber monitoring apparatus using optical pulse type, which can easily check the failure status of the optical cable (for example, the failure, the failed cable and the expected point of failure), and reduce the maintenance or installation cost, and its The purpose is to provide a method.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned above can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In order to solve the above problems, the present invention compares the pulses of the reflected light measured in the optical subscriber network optical cable on the subscriber side with the pre-measured steady state pulses to check the pulse type of the reflected light and based on the pulse type of the reflected light. It is characterized by checking the failure state of the optical cable.

More specifically, the apparatus of the present invention is an optical subscriber network optical cable monitoring apparatus, comprising: light incidence and extraction means for injecting test light into an optical subscriber network optical cable and extracting reflected light to the test light; Optical property measuring means for generating the test light and measuring pulses of the extracted reflected light; And an optical cable inspection means for checking the pulse type of the reflected light by comparing the measured pulse of the reflected light with the pulse of the normal state measured and checking the failure state of the optical cable based on the identified pulse type of the reflected light. Include.

The apparatus of the present invention further includes storage means for storing optical characteristic information for the measured steady state pulse and pulse type information for the fault condition.

On the other hand, the method of the present invention, in the optical fiber network cable monitoring method, the light incident and extraction step of generating a test light to enter the optical fiber network cable, and extracts the reflected light to the test light; An optical property measuring step of measuring a pulse of the extracted reflected light; And checking the pulse type of the reflected light by comparing the measured pulse of the reflected light with the pulse of the normal state measured and checking the failure state of the optical cable based on the identified pulse type of the reflected light. do.

As described above, the present invention compares the pulses of the reflected light measured in the optical subscriber network optical cable of the subscriber side with the pulses of the normal state measured in advance, and checks the pulse type of the reflected light and breaks the optical cable based on the pulse type of the reflected light. By checking the condition, it is possible to easily check the failure state of the optical cable (for example, the failure, the failed cable and the expected point of failure), and the effect of reducing the maintenance or installation cost can be achieved.

That is, the present invention, in a plurality of optical subscriber network structure (B-PON / E-PON / G-PON / WDM-PON network structure), the failure point in the optical subscriber network that the optical cable line is configured by the FTTH method Can be found stochasticly. In addition, the present invention, by periodically comparing with the database information about the expected failure point at the time of initial installation, it is possible to grasp in real time the situation that the transmission status of the optical subscriber network is gradually worsening, and may take precautions before the failure report of the subscriber It has an effect.

In addition, since the present invention does not require a device installed in the subscriber side or in the middle of the optical subscriber network, it is possible to efficiently manage the optical subscriber network in a completely centralized manner, and through such a centralized monitoring, the economy and operability are excellent. There is an effect that can be improved. For example, the present invention has the effect of easily operating and managing the optimized optical subscriber network by automatically updating the steady state of the optical cable even if the optical subscriber network changes.

The above objects, features, and advantages will be more clearly understood from the following detailed description with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention pertains may have the technical idea of the present invention. It will be easy to implement. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention analyzes the measurement result of the optical cable in the FTTH optical fiber network configuration of the B-PON / E-PON / G-PON / WDM-PON network structure, especially when each subscriber branched into multiple strands through a splitter It is about identifying the cables connected to the cables and probabilistically predicting the expected point in case of failure.

Here, the optical subscriber network refers to the construction of the subscriber network by the optical cable, and the passive optical network (PON), which is an optical communication network for the subscriber section (subscriber network), which is composed of only optical passive elements, which does not need a separate power supply. Applies to When the PON is compared according to a technical method, it is classified into a Gigabit Passive Optical Network (G-PON), an Ethernet PON (E-PON), and a Wavelength Division Multiplexing-PON (WDM-PON). The present invention is preferably applied to B / E / G-PON in such a passive optical subscriber network, and is applicable to other WDM-PON.

1 is a block diagram of an embodiment of an FTTH optical subscriber network to which the present invention is applied.

As shown in FIG. 1, the FTTH optical subscriber network to which the present invention is applied includes a transmission apparatus 110, a splitter 120, a modem 130 at a subscriber side, an optical cable monitoring device 140, and a coupler at a telephone station. 150). Here, the optical cable monitoring device 140 may be additionally connected to the database 160 and the operator terminal 170 through a network. Meanwhile, the database 160 may be implemented in the optical cable monitoring device 140.

The FTTH optical subscriber network refers to a subscriber network in which a transmission apparatus 110 of a telephone station and a modem 130 of a subscriber side are connected by an optical cable.

The telephone station generally includes a transmitting device (eg, an optical line terminal, etc.) 110. The optical cable is connected to the OLT transmission device 110 of the telephone station. This optical cable is also connected to the splitter 120 at the midpoint of the subscriber side. This is to increase the utilization by branching the communication light transmitted by the optical cable. And the optical cable is connected to the optical network terminal (ONT) device of the subscriber-side modem (130).

Splitter 120 is a splitter 121 for the PON to simply divide the light amount of the optical signal, and WDM-PON splitter 122 to separate the transmitted optical signal by the wavelength to the subscriber by splitting the wavelength until the splitter 120 inlet Separated by). The WDM-PON splitter 122 should have a structure in which an optical signal wavelength separated by wavelength and a monitoring wavelength are transmitted together, that is, a structure in which a pure PON splitter function and a WDM-PON splitter are combined.

The optical cable monitoring device 140 is connected to the optical cable between the OLT transmission device 110 and the splitter 120 of the telephone station through the coupler 150. Optical cable monitoring device 140 generates the test light to measure the optical cable and transmits to the subscriber side through the optical cable. The optical cable monitoring device 140 monitors the optical cable by comparing the characteristics of the reflected light reflected with the characteristics of the optical pulse of the steady state measured at the beginning.

The coupler 150 is for injecting test light generated by the optical cable monitoring device 140 to measure the optical cable to the optical cable, or for branching the reflected reflected light to the optical cable monitoring device 140. Here, the test light should have a test wavelength value different from the general communication wavelength generated by the OLT transmission device 110 of the telephone station. On the other hand, the filter between the OLT transmission device 110 and the coupler 150 of the telephone station is to eliminate the influence of the test wavelength generated by the optical cable monitoring device 140.

In addition, the database 160 stores the state information of the optical cable for the optical pulses received from the plurality of optical cable monitoring devices 140 and the failure point for the optical pulse type.

The operator terminal 170 provides the operator with the optical cable state information of the optical cable monitoring device 140 and the database 160. And the operator can control the optical cable monitoring device 140 through the operator terminal 170, it can grasp the failure state of the optical cable.

2A and 2B are diagrams illustrating an embodiment of an optical cable in an FTTH optical subscriber network.

)으로 구분된다.As shown in FIGS. 2A and 2B, a splitter 121 applied to a PON network uses a plurality of optical cables to connect an optical signal connected from a transmission apparatus 110 on a telephone station side to a modem 130 on a subscriber side. It performs the function of branching or multiplexing with one optical cable. The splitter 122 applied to the WDM-PON network, which is another method, splits an optical signal connected to the modem 130 of the subscriber station from the transmission apparatus 110 of the telephone station to the plurality of optical cables by wavelength. Alternatively, multiple optical signals of individual wavelengths in the upward direction are multiplexed into one optical cable. The splitter 121 branches one optical cable from the transmission device 110 of the telephone station to an electric pole or a home where a subscriber is located at an intermediate point, or branches into several strands, or N strands, in an apartment premises communication room (FIG. 2b). This is to allow multiple subscribers to communicate over the optical cable at the same time. Here, the wavelength transmitted to the optical cable is the information wavelength for the communication light and the monitoring wavelength (for the test light)

).

)과 모니터링 파장(

)으로 구분된다.At this time, the splitter 122 applied to the WDM-PON network branches or multiplexes the optical cable so that a plurality of different subscribers can communicate through the optical cable. For example, the wavelength transmitted by the optical cable connected to the splitter 122 is the information wavelength (corresponding to the first to n-th subscriber)

) And the monitoring wavelength (

).

Hereinafter, the optical cable monitoring device 140 for monitoring the characteristics of the optical cable in the FTTH subscriber network will be described.

3 is a block diagram of an optical subscriber network optical cable monitoring apparatus using the optical pulse type according to the present invention.

As shown in FIG. 3, the optical cable monitoring device 140 includes an optical incident and extracting unit 310, an optical characteristic measuring unit 320, and an optical cable inspecting unit 330.

The optical incidence and extraction unit 310 selects a specific optical cable from among the numerous optical cables installed from the transmission apparatus 110 of the telephone station to the modem 130 of the subscriber side, and then enters the test light into the optical subscriber network optical cable of the subscriber side. And extracts the reflected light transmitted from the subscriber side.

The optical characteristic measuring unit 320 measures the optical characteristics of the optical cable selected by the light incident and extracting unit 310 by using a time band optical reflection (OTDR) measuring apparatus. That is, the optical property measuring unit 320 generates a test light pulse to be incident on the optical fiber, and measures the backscattered light, which is part of the reflected light, extracted by the light incident and extracting unit 310.

The optical cable inspecting unit 330 analyzes the optical characteristic test results in the optical characteristic measuring unit 320 to identify a failure point of the optical cable. That is, the optical cable inspecting unit 330 checks the pulse type of the reflected light by comparing the pulse of the reflected light measured by the optical characteristic measuring unit 320 with the pulse of the normal state measured in advance. And the optical cable inspection unit 330 checks the failure state of the optical cable based on the pulse type of the reflected light. In addition, the optical cable inspection unit 330 controls the light incident and extracting unit 310 and the optical property measuring unit 320, and is connected to the database 160 and the operator terminal 170 through a network. Here, the database 160 stores the optical characteristic information of the pulse in the normal state and the pulse type information of the fault state.

When the optical cable construction is completed, the operation of the optical cable monitoring device 140 is considered as an initial installation point. At the time of initial installation, the optical characteristic measuring unit 320 measures an optical cable using a time band optical reflectance measuring apparatus (OTDR). The optical property measurement result at the time of initial installation becomes a standard of steady state. The optical cable inspection unit 330 transmits the optical characteristic measurement result to the database 160. Then, the database 160 stores the optical characteristic measurement results transmitted from the optical characteristic measurement unit 320 as pulses in a steady state.

At this time, when the new subscriber-side modem 130 is connected to the splitter 120, the optical characteristic measuring unit 320 measures the optical characteristic using the time-band optical reflectance measuring device. The optical cable inspection unit 330 transmits the newly measured optical characteristic measurement result to the database 160 in order to update the measurement result in the steady state. This is to use the newly measured measurement result as a reference for the steady state pulse. The database 160 changes and stores the previous optical characteristic measurement result into a newly measured optical characteristic measurement result.

The optical characteristic measuring unit 320 may be previously inputted in advance or may be input from a user when the optical cable is periodically measured or the optical cable to be measured. This is to periodically monitor the status of the optical cable. And the optical characteristic measuring unit 320 automatically measures the characteristics of the optical cable at a set cycle.

The optical cable inspecting unit 330 analyzes the optical characteristic measurement results measured by the optical characteristic measuring unit 320 and distinguishes each optical cable connected to different subscribers. That is, the optical cable inspection unit 330 compares the pulse waveform generated at the end point of the optical cable and the pulse waveform of the steady state measured in advance to distinguish the pulse waveform for different optical cables. Here, when a failure point or breakage point occurs in the optical cable, the pulse waveform is absent or changed at a designated position different from the normal pulse measured in advance. Therefore, the optical cable inspecting unit 330 analyzes the changed pulse waveforms with the pulse waveforms in the normal state, thereby probably predicting or inferring the optical cable in which the failure occurs.

In detail, comparing items, the optical cable inspection unit 330 sets the start point of the pulse, the width of the pulse, and the height of the pulse with respect to the measured pulse of the reflected light and the pulse in the steady state. In comparison between these pulses, the optical cable inspection unit 330 determines whether the threshold value set by the user is exceeded and determines that the pulse is changed from the pulse in the normal state.

The optical cable inspecting unit 330 divides the area to be compared and analyzed with respect to the start point and the end point of each pulse into a plurality of areas, and stores the divided areas in the database 160.

In order to accurately identify the failure point, the optical cable inspection unit 330 analyzes the pulse type for each of the steady state pulses and the measured reflected pulses to find the failure point of the optical cable. The pulse type for the failure point is prestored in the database 160.

In addition, the optical cable inspection unit 330 sequentially starts the analysis area from 0km, which is the modem 130 of the subscriber, using the optical characteristic measurement result measured by the optical characteristic measuring unit 320, and sequentially analyzes the analysis region with one-to-one pulses. Compare with. The optical cable inspection unit 330 compares the compared pulse types with the pulse types stored in the database 160 to find a similar pulse type.

The optical cable inspecting unit 330 classifies the information on the occurrence of one or more connection point failures into pulse types for a plurality of failure points and stores the information in a database 160. In addition, the optical cable inspection unit 330 periodically stores the pulse type for the optical characteristic measurement results in the database 160 so that the optical cable can be periodically monitored. When the failure point occurs at the same end point, the optical cable inspection unit 330 checks the optical cable in which the failure point occurs in association with a signal of the modem 130 on the subscriber side.

The optical cable inspecting unit 330 may receive a failure alarm signal directly from the OLT transmission device 110 at the telephone station or from an OLT management device (not shown). And the optical cable inspection unit 330 transmits the failure occurrence alarm signal to the optical characteristic measurement unit 120. The optical characteristic measuring unit 120 receiving the failure alarm signal automatically measures the pulse of the reflected light of the optical cable connected to the corresponding OLT transmission device 110 and transmits the measurement result to the optical cable inspection unit 330.

On the other hand, if the optical cable inspection unit 330 is a PON structure, the optical cable inspection unit 330 can centrally monitor the end of the optical cable (optical path).

In the case of an optical subscriber network using a wavelength division multiplexing (WDM-PON) scheme, the optical cable inspection unit 330 may monitor the individual subscriber optical cable ends in a centralized manner by performing a monitoring function using a monitoring wavelength. In addition, when the optical subscriber network is a WDM-PON structure, the optical cable inspection unit 330 is a light incidence and extraction unit 310 and the light so as to branch the monitoring wavelength to all wavelength channels in an array branch length (AWG) The characteristic measuring unit 320 is controlled. In addition, when the optical subscriber network has a WDM-PON structure, the optical cable inspecting unit 330 may centrally monitor the optical cable to the end of the optical cable using a monitoring wavelength.

FIG. 4 is a diagram illustrating results of optical properties measured in an optical subscriber network to which a 1 × 4 splitter is applied. FIG.

In the optical subscriber network to which the 1 × 4 splitter is applied, the optical property measurement result measured by the optical property measurement unit 320 is illustrated in the graph of FIG. 4. The x-axis of the graph represents distance, and the y-axis represents magnitude in dB.

As shown in FIG. 4, a total of six pulses are shown as reflected pulses. The two pulse waveforms 401 appearing from left to right are due to the splitter. The remaining four pulse waveforms 402 are pulse waveforms of reflected light reflected after passing through the splitter. Here, four pulse waveforms are sequentially defined as pulse waveforms # 1, # 2, # 3, and # 4, and pulse waveforms # 1, # 2, # 3, and # 4 are user terminals # 1, # 2, and # 4. It is connected to 3 and # 4 respectively. The optical characteristic measuring unit 320 measures the start point 404 of the pulse, the end point 405 of the pulse, and the height 406 of the pulse. The width 403 of the pulse may be obtained from the start point 404 and the end point 405 of the pulse. Information about the pulse waveform is analyzed by the optical cable inspection unit 330 and stored in the database 160.

5 is a structural diagram of an embodiment of an optical fiber network connected to a 1 × 4 splitter.

The 1 × 4 splitter, which splits the optical cable, is connected to the optical fiber of the subscriber network. In this case, the optical subscriber network optical cable is installed so that the length of the subscriber cable is different from each other so that the subscriber cable. In other words, the length of the optical cable is increased so that the cable length is distinguished from each other.

In order to easily explain the concept of the present invention, the most simplified 1x4 splitter is used. That is, the structure of the optical cable branched into four subscriber stations will be described.

The user terminals # 1, # 2, # 3, and # 4 are located at a distance from the splitter. That is, the user terminals # 1, # 2, # 3, and # 4 are located at points a, c, f, and j, respectively. For example, if the distance between the user terminals # 1, # 2, # 3, # 4 is the same and the distance between each terminal is 10m, the user terminal # 1 at the point a is 10m away from the splitter. Similarly, the user terminals # 2, # 3, # 4 at points c, f, and j are 20m, 30m, and 40m away from the splitter. In this optical cable structure, the result measured by the optical characteristic measuring unit 320 coincides with the pulse waveform shown in FIG. 4.

The pulse waveform shown in FIG. 4 will be described through the structure of FIG. 5.

The pulse waveform from left to right shown in FIG. 4 represents the measured pulse waveform from the telephone station to the customer terminal. 4 is enlarged for convenience of explanation, and the state of the optical cable from the telephone station to the splitter is displayed horizontally long on the left side. The fiber optic cable runs from the telephone station to about 0.365 km. At the splitter point (between about 0.365 and 0.40 km), a pulse waveform 401 is shown as a physical property. Immediately following four pulse waveforms 402 for user terminals # 1, # 2, # 3, and # 4.

FIG. 6 is a diagram illustrating an exemplary embodiment of a pulse waveform measured by an optical cable disconnected from point b in FIG. 5.

Looking at the result of the optical cable disconnected point b in Figure 5 measured by the optical characteristic measurement unit 320, it can be seen that the pulse waveform # 2 (602) is changed compared to the pulse 601 in the steady state. That is, it is confirmed that the start point, end point, and height of the measured pulse waveform # 2 602 have changed. Here, pulse waveform # 2 602 corresponds to the distance corresponding to point b from the splitter.

In addition, due to the disconnection at point b, the pulse waveform # 1 immediately before the pulse waveform # 2 602 may be changed.

FIG. 7 is a diagram illustrating a pulse waveform obtained by measuring an optical cable disconnected at point d in FIG. 5.

Referring to the result of the optical cable disconnected at point d measured by the optical characteristic measuring unit 320 in FIG. 5, it can be seen that there is no pulse waveform # 3 at the position where the pulse 701 in the steady state was present. Here, pulse waveform # 3 corresponds to a distance corresponding to point d from the splitter.

In addition, due to the disconnection at the d point, the pulse waveforms of the pulse waveforms # 1 and # 2 in front of the pulse waveform # 3 may also be changed.

FIG. 8 is a diagram illustrating an exemplary embodiment of a pulse waveform of measuring an optical cable disconnected by point g in FIG. 5.

Referring to the result of measuring the optical cable disconnected by point g in FIG. 5 by the optical characteristic measuring unit 320, it can be seen that as shown in FIG. 7, there is no pulse waveform # 4 at the position where the steady state pulse 801 was located. . Here, pulse waveform # 4 corresponds to a distance corresponding to point g from the splitter.

In addition, due to disconnection at point g, pulse waveforms # 1, # 2, and # 3 in front of pulse waveform # 4 may also be changed.

The optical cable inspecting unit 330 stores all the types of change of the pulses shown in FIGS. 6 to 8 in a database and stores them in the database 160. In addition, the optical cable inspection unit 330 predicts a failure point by comparing with the various situational information already databased for the case of the pulse type of the steady state. The results of the database of these various contextual information are shown in Table 1 below.

Three pulse waveforms # 2, # 3, and # 4 corresponding to points c, f, and j in FIG. 5 will be described. The total number of cases in which both the pulses are present and the pulses are absent is eight, as shown in Table 1 above.

In addition, when point e is disconnected in FIG. 5, it is combined with a pulse generated due to point c. If point i is broken, it merges with the pulse at point f. For example, the rule that appears in a pulse is that the pulse appears at the break point. That is, if it is disconnected at point e and h, the pulses to appear at point f and the pulses to appear at point j, that is, pulse waveforms # 3 and # 4, are lost.

Therefore, the number of cases of the broken state by different combinations of points b, d, e, g, h, and i is 56, as shown in Tables 2 to 4 below. It can be compared with the eight pulse types in Table 1 above. In addition, pulse type information about a failure state (for example, an expected failure point, disconnection of an optical cable, a relationship with another optical cable, etc.) shown in Tables 2 to 4 below is stored in the database 160. .

[Table 2] shows the pulse type for the case where one optical cable is broken. In addition, [Table 3] shows the pulse type for the case where two optical cables are disconnected. In addition, Table 4 above shows the pulse types for the case where three optical cables are disconnected.

After storing the pulse type as shown in Table 2 to Table 4 in the database 160, the optical cable inspection unit 330 predicts the failure prediction point according to the pulse type. For example, a pulse type of "Oox" indicates that a failure has occurred at any one of {G, h, I, di, id, ei, ie, gh, hg, gi, ig, hi, ih} points. Sends a message to the operator terminal (170).

In this way, the optical pulse type can be used to determine the expected failure point.

However, for the same pulse type (eg oxx), as shown in Table 3, 'dg, gd, dh, hd, eg, ge, eh, he, bdh, beg, beh, bge, bhe, bhd' There is a probability of failure in either. Therefore, in order to distinguish between two different optical cables, the optical cable monitoring device 140 communicates with the modem 130 of the subscriber side (ONT) connected to the points a, c, f, and j respectively. By checking, the correct classification is possible.

9 is a diagram illustrating an example of comparing pulse types in the optical cable inspecting unit according to the present invention.

The optical cable inspecting unit 330 checks the presence or absence of a pulse corresponding to each point by comparing the pulse waveform of the steady state shown in FIG. In this case, the criterion for determining the presence or absence of a pulse is a start point, a width, and a height (or a start point, an end point, and a height) of the pulse. The optical cable inspection unit 330 determines the presence or absence of a pulse according to whether or not the measured start point, width, and height of the measured pulse fall within a threshold allowance for the measured start point, width, and height of a steady state pulse. Send it.

10A and 10B are diagrams illustrating an embodiment of a comparison process using a mask technique in the optical cable inspection unit according to the present invention.

As shown in FIGS. 10A and 10B, the optical cable inspecting unit 330 uses a mask comparison technique as a bitmap operation on an image of a measured pulse in order to compare the presence or absence of a pulse at a fast CPU operation speed. Here, the mask comparison technique widens the width by a margin of error from the peak to the mask. In the mask comparison technique, the image of the actual measurement waveform is compared pixel by pixel, and the deviation is calculated as the number of pixels deviating from the mask area.

10A shows a mask image 1001 for a steady state pulse waveform. In FIG. 10B, an image 1002 of an actual measured waveform is superimposed on a mask image of a pulse waveform in a steady state.

The optical cable inspecting unit 330 determines a threshold allowance (for example, the number of critical blocks) that deviates from the mask image 1002 for the pulse waveform in the steady state, and determines the presence or absence of a pulse according to the threshold allowance. That is, if the image 1002 of the actual measured waveform is larger than the block threshold tolerance, the optical cable inspection unit 330 determines that the measured pulse does not exist. On the other hand, if less than the threshold tolerance, the optical cable inspection unit 330 determines that the measured pulse is present.

"(1001)를 만든다. 그리고 광케이블 검사부(330)는 이 이미지(1001) 영역 내에 측정된 펄스의 이미지 "

"(1002)가 존재하는지 비트 연산(XOR 연산)을 수행한다. 그 비트 연산 결과에 따라, 광케이블 검사부(330)는 마스크 이미지 "

"(1001)에서 벗어난 펄스의 이미지(1002)가 몇 개 인지를 계산하여 임계 허용치를 넘으면 펄스 파형이 존재하지 않는 것으로 결정한다.Specifically, the optical cable inspection unit 330 is a mask image "to the threshold tolerance of the pulse"

&Quot; 1001. And the optical cable inspection section 330 shows an image of the pulse measured in the area of this image 1001 "

A bit operation (XOR operation) is performed to determine whether 1002 exists. According to the bit operation result, the optical cable inspection unit 330 performs a mask image.

It calculates how many images 1002 of the pulse deviated from " 1001 " and determines that no pulse waveform exists if it exceeds the threshold tolerance.

Meanwhile, the optical cable inspecting unit 330 may use an image comparison method other than the comparison method using the mask technique.

11 is a flowchart illustrating a method for monitoring an optical fiber network using an optical pulse type according to the present invention.

The optical characteristic measuring unit 320 generates test light having a specific wavelength for measuring optical characteristics. The light incident and extracting unit 310 enters the test light generated by the optical property measuring unit 320 into a specific optical cable to be tested.

In addition, when the light incident and extraction unit 310 extracts the backscattered light (reflected light) that is reflected and returns to the optical property measuring unit 320, the optical property measuring unit 320 measures the optical property of the back scattered light. . That is, the optical characteristic measuring unit 320 measures a pulse waveform corresponding to the backscattered light.

Subsequently, the optical subscriber network optical cable monitoring process using the optical pulse type in the optical cable inspection unit 330 will be described in detail.

The optical cable inspecting unit 330 obtains a steady state pulse type stored in the database 160 (1102).

The optical cable inspection unit 330 reads the analysis region stored in the database 160 (1104). The optical cable inspection unit 330 sets the read analysis area as the first analysis area (1106).

Subsequently, the optical cable inspecting unit 330 compares the normal pattern and the measurement result with respect to the current analysis area (1108).

Thereafter, the optical cable inspecting unit 330 checks whether a pulse exists in the analysis region (1110).

As a result of the check 1110, if there is a pulse in the analysis region, the optical cable inspection unit 330 displays a normal display in the current region according to the measurement result (1112). On the other hand, if there is no pulse in the analysis area, the optical cable inspection unit 330 displays an abnormality in the current area according to the measurement result (1114).

The optical cable inspecting unit 330 checks whether the next analysis region exists (1116).

As a result of the check 1116, if the next analysis region exists, the optical cable inspection unit 330 moves to the next analysis region (1118), and repeats the process from "1108". On the other hand, if the next analysis region does not exist, the optical cable inspection unit 330 checks whether or not an abnormal indication is displayed on the measurement result pattern (pulse type) (1120).

When the check result 1120 and the measurement result pattern is displayed abnormally, the optical cable inspection unit 330 checks the failure prediction point stored in the database 160 in a pattern compared with the measurement result and the operator predicts the failure prediction point. 170) (1122). On the other hand, if the measurement result pattern is normal display, the optical cable inspection unit 330 displays the state of the optical cable as normal and transmits to the operator terminal 170 (1124).

In addition, for quick tracking of the failure point, the optical cable monitoring device 140 receives a failure alert directly from the transmission device (OLT) 110 on the telephone station side or from the transmission device (OLT) management system on the phone station side and transmits the corresponding alarm. Automatically test the optical cable to which the device (OLT) is connected.

On the other hand, the method of the present invention as described above can be written in a computer program. And the code and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), and read and executed by a computer to implement the method of the present invention. The recording medium may include any type of computer readable recording medium.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

1 is a configuration diagram of an embodiment of an FTTH optical subscriber network to which the present invention is applied;

2A and 2B are diagrams illustrating an embodiment of an optical cable in an FTTH optical subscriber network;

3 is a configuration diagram of an optical subscriber network optical cable monitoring apparatus using an optical pulse type according to the present invention;

4 is a diagram showing results of an embodiment of optical characteristics measured in an optical subscriber network to which a 1 × 4 splitter is applied;

5 is a structural diagram of an embodiment of an optical fiber network connected to a 1 × 4 splitter;

FIG. 6 is a diagram illustrating an exemplary embodiment of a pulse waveform measured by an optical cable disconnected from point b in FIG. 5;

FIG. 7 is a diagram illustrating a pulse waveform obtained by measuring an optical cable of point d disconnected in FIG. 5;

FIG. 8 is a diagram illustrating an exemplary embodiment of a pulse waveform of measuring an optical cable disconnected by point g in FIG. 5;

9 is an exemplary explanatory diagram for comparing pulse types in the optical cable inspection unit according to the present invention;

10A and 10B illustrate an embodiment of a comparison process using a mask technique in an optical cable inspection unit according to the present invention;

11 is a flowchart illustrating a method for monitoring an optical fiber network using an optical pulse type according to the present invention.

* Explanation of symbols for the main parts of the drawings

110: transmission unit on the telephone station side 120: splitter

130: modem of subscriber side 140: optical cable monitoring device

150: coupler 160: database

170: operator terminal 310: light incident and extraction unit

320: optical characteristic measurement unit 330: optical cable inspection unit

Claims (35)

In the optical subscriber network optical cable monitoring device, Light incidence and extraction means for injecting test light into an optical subscriber network optical cable and extracting reflected light to the test light; Optical property measuring means for generating the test light and measuring pulses of the extracted reflected light; And An optical cable inspection means for checking the pulse type of the reflected light by comparing the measured pulse of the reflected light with a pulse in the normal state measured and checking the fault condition of the optical cable based on the identified pulse type of the reflected light Optical subscriber network optical cable monitoring device using an optical pulse type comprising a. The method of claim 1, Storage means for storing optical characteristic information on the measured steady state pulse and pulse type information on the fault condition Optical subscriber network optical cable monitoring device using an optical pulse type further comprising. The method of claim 2, The optical cable inspection means, An optical subscriber network optical cable monitoring apparatus using an optical pulse type, characterized by dividing an area to be compared and analyzed with respect to a start point and an end point of each pulse into at least one analysis area. The method according to any one of claims 1 to 3, The optical cable inspection means, Optical fiber monitoring apparatus using the optical pulse type, characterized in that the pulse of the reflected light measured at the time of the first installation of the optical cable is specified as the pulse of the steady state. The method of claim 4, wherein The optical cable inspection means, The optical subscriber network optical cable monitoring apparatus using the optical pulse type, characterized in that the pulse of the steady state is updated by using the reflected light pulse measured by the optical characteristic measuring means after the new subscriber optical cable is connected. . The method according to any one of claims 1 to 3, The optical characteristic measuring means, And monitoring the failure state of the optical cable to be measured periodically under the control of the optical cable inspection means with respect to the optical cable to be measured and the periodic time point. The method according to any one of claims 1 to 3, The optical cable inspection means, And a specific pulse corresponding to a specific optical cable according to a pulse position in the measured pulses of the reflected light. The method of claim 7, wherein The optical cable inspection means, And monitoring the presence or absence of the identified specific pulse by comparing the measured starting point, width, and height of the pulse of the reflected light with the threshold tolerance of the normal pulse. The method of claim 8, The optical cable inspection means, Optical fiber monitoring device using the optical pulse type, characterized in that for checking the failure state of the specific optical cable in accordance with the presence or absence of the identified specific pulse. The method according to any one of claims 1 to 3, The optical cable inspection means, And using a mask technique to compare the measured pulses of reflected light with a threshold tolerance for the pulses in the steady state. The method according to any one of claims 1 to 3, The optical cable inspection means, Optical fiber monitoring apparatus using the optical pulse type, characterized in that for identifying the failure point corresponding to the pulse type of the reflected light from the pulse type information on the measured failure point of the optical cable. The method according to any one of claims 1 to 3, The optical cable inspection means, The optical subscriber network optical cable monitoring apparatus using the optical pulse type, characterized in that to find the corresponding pulse type by comparing the analysis region for the measured pulse of the reflected light with the pulse of the steady state. The method according to any one of claims 1 to 3, The optical characteristic measuring means, And monitoring the optical cable periodically to update the pulse type information on the measured pulse type of the reflected light from time to time. The method according to any one of claims 1 to 3, The optical cable inspection means, When the failure occurs at the same end point of the pulse type of the measured reflected light, the optical fiber monitoring apparatus using the optical pulse type, characterized in that identifying the faulty optical cable in conjunction with the subscriber-end modem signal. The method according to any one of claims 1 to 3, The optical cable inspection means, The optical cable monitoring apparatus using the optical pulse type, characterized in that the automatic inspection of the optical cable connected to the transmission device of the telephone station side in response to receiving a failure alarm signal from the telephone station side. The method according to any one of claims 1 to 3, The optical cable inspection means, The optical subscriber network optical cable monitoring apparatus using the optical pulse type, characterized in that if the optical subscriber network has a PON structure, the telephone station intensively monitors to the end of the optical path. The method according to any one of claims 1 to 3, The optical cable inspection means, The optical subscriber network optical cable monitoring device using the optical pulse type, characterized in that when the optical subscriber network is WDM-PON structure to monitor from the center to the end of the optical path intensively by the monitoring wavelength. The method according to any one of claims 1 to 3, The optical cable inspection means, The optical subscriber network optical cable monitoring apparatus using the optical pulse type, characterized in that for the WDM-PON structure of the optical subscriber network, branching the monitoring wavelength to all wavelength channels in the intermediate branch. The method according to any one of claims 1 to 3, The optical subscriber network optical cable, Optical fiber monitoring apparatus using an optical pulse type, characterized in that it comprises a plurality of subscriber optical cables having different lengths to be distinguished from each other. The method of claim 19, The pulse type information, Optical fiber monitoring device using the optical pulse type, characterized in that for each of the optical cable comprises a pulse type for a plurality of failure points. In the optical subscriber network optical cable monitoring method, A light incidence and extraction step of generating test light and incident the light into the optical fiber network cable and extracting the reflected light to the test light; An optical property measuring step of measuring a pulse of the extracted reflected light; And An optical cable inspection step of checking a pulse type of the reflected light by comparing the measured pulse of the reflected light with a pulse of a normal state measured and checking a failure state of the optical cable based on the identified pulse type of the reflected light Optical subscriber network optical cable monitoring method using an optical pulse type comprising a. The method of claim 21, The optical cable inspection step, The optical member monitoring method using the optical pulse type, characterized in that the pulse of the reflected light measured at the time of the first installation of the optical cable is specified as the pulse of the steady state. The method of claim 22, The optical cable inspection step, If the new subscriber optical cable is connected, the optical fiber monitoring method using the optical pulse type, characterized in that for updating the pulse of the steady state by using the reflected light pulse measured after the connection of the new subscriber optical cable. The method according to any one of claims 21 to 23, The optical characteristic measurement step, The optical cable monitoring method using the optical pulse type, characterized in that for periodically monitoring the failure state of the optical cable to be measured at the request of the optical cable and the periodic time point. The method of claim 24, The optical cable inspection step, And a specific pulse corresponding to a specific optical cable according to a pulse position in the measured pulses of the reflected light. The method of claim 25, The optical cable inspection step, And comparing the starting point, width, and height of the measured pulses of reflected light with a threshold allowance of a normal pulse to confirm the presence or absence of the identified specific pulse. The method of claim 26, The optical cable inspection step, Optical fiber monitoring method using the optical pulse type, characterized in that for checking the failure state of the specific optical cable according to the presence or absence of the identified specific pulse. The method according to any one of claims 21 to 23, The optical cable inspection step, And using a mask technique to compare the measured pulses of reflected light with a threshold tolerance for the steady-state pulses. The method according to any one of claims 21 to 23, The optical cable inspection step, The optical fiber monitoring method using the optical pulse type, characterized in that for identifying the failure point corresponding to the pulse type of the reflected light from the pulse type information on the measured failure point of the optical cable. The method according to any one of claims 21 to 23, The optical cable inspection step, The optical member monitoring method using the optical pulse type, characterized in that to find the corresponding pulse type by comparing the analysis region for the measured pulse of the reflected light with the pulse of the steady state. The method according to any one of claims 21 to 23, The optical characteristic measurement step, And monitoring the optical cable periodically to update pulse type information on the measured pulse type of the reflected light from time to time. The method according to any one of claims 21 to 23, The optical cable inspection step, The optical fiber monitoring method using the optical pulse type, characterized in that for identifying the failure optical cable in conjunction with the subscriber-end modem signal, when the failure occurs at the same endpoint. The method according to any one of claims 21 to 23, The optical cable inspection step, The optical cable monitoring method using the optical pulse type, characterized in that the automatic inspection of the optical cable connected to the transmission device of the telephone station side in response to receiving a failure alarm signal from the telephone station side. The method according to any one of claims 21 to 23, The optical cable inspection step, The optical subscriber network optical cable monitoring method using the optical pulse type, characterized in that for monitoring the optical cable end intensively from the center to the end of the optical cable using the monitoring wavelength when the optical subscriber network has a WDM-PON structure. The method according to any one of claims 21 to 23, The optical cable inspection step, The optical subscriber network optical cable monitoring method using the optical pulse type, characterized in that for the WDM-PON structure, branching the monitoring wavelength to all wavelength channels in the middle branch.

Images