KR102091396B1 - Optical cable attach type otdr - Google Patents

Abstract

The present invention relates to an OTDR and, more particularly, to an optical cable attached type OTDR. The present invention is designed to provide an optical cable attached type OTDR capable of accurately predicting a point of failure in an optical cable in a section between a repeater and a repeater, a section between a repeater and a base station, and a section between a base station and a base station. According to a desirable embodiment of the present invention an optical cable attached type OTDR includes: a first optical connector for optical connection with a repeater or a base station; and a second optical connector for connection with an optical cable, wherein the first optical connector and the second optical connector are optically connected through a connection optical line and the OTDR further includes a controller for monitoring the intensity of the optical signal on the optical cable by using an optical signal on the connection optical line. In the present invention, the OTDR is installed in a section between a repeater and a repeater, a section between a repeater and a base station, and a section between a base station and a base station, thereby accurately predicting the point of failure in the optical cable in the section between the repeater and the repeater, the section between the repeater and the base station, and the section between the base station and the base station.

Description

Optical Fiber Attachment Type OTDR {OPTICAL CABLE ATTACH TYPE OTDR}

The present invention relates to OTDR, and more particularly, to an optical path attached OTDR.

Recently, various communication devices have been developed and used, the number of people using the Internet has increased, and data traffic has increased exponentially with the advent of new multimedia services. Accordingly, the entire network is evolving so that large data can be exchanged.

In particular, due to the explosive increase of the Internet, intranets, extranets, etc. in urban areas, the amount of transmission in the city's internal networks is increasing, and optical communication technology has been used as a technique for resolving traffic due to the rapid increase in data transmission.

Equipment such as an optical power meter and OTDR are used for maintenance and maintenance of such an optical transmission system. The optical power meter is a device that monitors the power of transmitted and received light. OTDR detects Fresnel reflections at the break point or Rayleigh scattering in the optical fiber by using the pulse as a signal to inject the optical pulse into the optical fiber to be measured. Measure the failure point or loss characteristics of.

1 is a view for explaining a conventional optical path monitoring system and optical path trajectories under normal conditions. The existing fiber optic monitoring system was centralized. That is, one OTDR is installed in a central optical terminal (COT), and a structure in which one OTDR monitors a plurality of optical paths (A route / B route in FIG. 1) branched from RT. In the normal state, the trajectory of the optical path is shown in FIG. 1. The farther away from the OTDR light source, the less reflected light received from the OTDR. At this time, the optical connection point (RT (Remote Terminal), RU (RF Unit), RRU (Remote Radio Unit)) located on the optical path and the reflected light received at the optical end position is a form that increases abnormally. By detecting such an abnormal point, the OTDR can predict the failure section.

FIG. 2 shows a ray trajectory when a cut event occurs in route A of FIG. 1.

In FIG. 2, it can be seen that a light path cutting event occurred 27 km from the COT. However, a point 27 km away from the COT may be the optical end of the B route. Therefore, the OTDR installed in the COT has a problem in that it is not possible to distinguish whether the non-ideal reflected light increase event at a point 27 km away from the COT is caused by a truncation event or a light termination. Furthermore, there is a problem in that it is not possible to distinguish which of the A route and the B route occurred in the case of the light cut event at a point 20 km away from the COT.

The following prior patents related to optical fiber monitoring exist.

Domestic registered patent No. 10-0492193 is equipped with a function of measuring optical fiber loss / reflection characteristics at each wavelength by mounting a plurality of light sources of different wavelengths and driving each light source individually, while driving a plurality of light sources. About OTDR (Optical Time Domain Reflectometer), which can measure additional internal characteristics of optical fiber such as Raman gain constant, Raman gain effective distance, double rail line scattering of optical fiber by selecting and receiving only Rayleigh backscattering at only one light source wavelength It starts.

Domestic registered patent No. 10-1587091 includes connecting a wavelength-dependent reflective (HRD) element to the optical path at a first position; Emitting light at the first wavelength (l1) and the second wavelength (l2) to the optical path by using optical communication measuring means (22) connected to the optical path at a position remote from the reflective element; The first and second OTDR traces (OTDR-l1) of the detected back reflected light, respectively, corresponding to the first wavelength (l1) and the second wavelength (l2) are detected from the corresponding back reflected light from the optical paths. OTDR-l2) respectively as a function of optical distance from the point; Comparing first and second OTDR traces to distinguish a peak corresponding to the wavelength-dependent reflective element from peaks corresponding to the wavelength-independent reflective events; And outputting at least one parameter value of the distinguished peak as a measure of the parameter of the wavelength-dependent reflective element, and a method of extracting the parameter of the optical path from the optical communication network using a 2-wavelength optical communication instrument and the wavelength-dependent reflective element. Disclosed.

Both of these patents disclose only a technique for improving the accuracy of the failure location of the centrally installed OTDR. That is, even if the fault location is accurately measured according to the above method, the limitations of the centralized OTDR method described above still exist.

Domestic registered patent No. 10-0492193 Domestic registered patent No. 10-1587091

Accordingly, an object of the present invention is to propose an optical path attachment type OTDR capable of accurately predicting a point of failure of an optical fiber in a section between a repeater and a repeater, a section between a repeater and a base station, and a section between a base station and a base station.

The optical path attachment type OTDR according to the preferred embodiment of the present invention includes a first optical connector for optical connection with a repeater or a base station; And a second optical connector for connection with the optical path, wherein the first optical connector and the second optical connector are optically connected through a connecting optical line, and the optical signal intensity on the optical path using an optical signal on the connecting optical line It further includes a control unit for monitoring.

Here, an optical coupler installed on the connecting optical line; A second optical switch installed between the optical coupler and the control unit; And a PD (Photo Diode) installed between the second optical switch and the control unit. A first optical switch installed between the second optical connector and the optical coupler; An optical circular radar installed between the first optical switch and the second optical switch; And an LD (Laser Diode) installed between the optical circulator and the controller, wherein the controller is configured to connect the first optical switch between the second optical connector and the optical coupler in a signal strength monitoring mode. Switching, so that the second optical switch connects the optical coupler and the PD, and the controller controls the first optical switch to connect the second optical connector and the optical circulator in an abnormal point detection mode. The second optical switch can be switched to connect the optical circulator and the PD.

In addition, in the signal strength monitoring mode, the control unit compares the strength of the transmission / reception signal on the optical path with a reference signal to determine whether the optical signal is normally flowing, and if the intensity of the optical signal is lower than the reference signal, the control unit switches to the abnormal point detection mode And, in the abnormal point detection mode, an operation for finding an abnormal point on the optical path may be performed.

In addition, further comprising an IoT module for communication between the control unit and the upper node, the control unit provides the optical path status information to the upper node through the IoT module, together with the optical path status information, the base station or repeater ID Can be provided to the parent node.

In the present invention, an OTDR is installed for each section between a repeater and a repeater, a section between a repeater and a base station, and a section between a base station and a base station, and a point of failure of an optical fiber in a section between a repeater and a repeater, a section between a repeater and a base station, and a section between a base station and a base station. It can be accurately predicted.

1 is a view for explaining a conventional optical path monitoring system and optical path trajectories under normal conditions.
FIG. 2 shows a ray trajectory when a cut event occurs in route A of FIG. 1.
3 shows an example of a fiber optic system to which a fiber optic attached OTDR is applied according to one preferred embodiment of the present invention.
4 shows a functional block diagram of an optical path attachment type OTDR according to one preferred embodiment of the present invention.
5 is a view for explaining the state of the switch in the signal strength monitoring mode.
6 is a view for explaining the state of the switch in the abnormal point detection mode.

The present invention can be applied to various changes and may have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing each drawing, similar reference numerals are used for similar components. In the description of the present invention, when it is determined that a detailed description of known technologies related to the present invention may obscure the subject matter of the present invention, the detailed description will be omitted.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components.

For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component.

The term and / or includes a combination of a plurality of related described items or any one of a plurality of related described items.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but other components may exist in the middle. It should be.

On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

The terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention.

Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "include" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts or combinations thereof described herein, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains.

Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

Hereinafter, an optical path attachment type OTDR according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

3 shows an example of a fiber optic system to which a fiber optic attached OTDR is applied according to one preferred embodiment of the present invention.

Referring to FIG. 3, an OTDR 10 is installed for each repeater and base station. The installation structure will be described later. In FIG. 3, COT, RT, RU, and RRU represent examples of units installed in a repeater or base station. In the OTDR 10 of the present invention, one OTDR is mounted on one optical path for each optical route.

4 shows a functional block diagram of an optical path attachment type OTDR 10 according to one preferred embodiment of the present invention. Instead of directly connecting the existing optical cable by directly connecting the optical cable entering the repeater to the input port of the line-attached OTDR proposed in the present invention and connecting the output port and the repeater with an optical jumper cable, monitoring the real-time optical path by passing through the line-attached OTDR It is possible.

Specifically, in FIG. 4, a repeater is provided in a repeater or a module in a base station, and an optical connector 21 is provided at the repeater 22 side.

Optical connectors 11 and 12 are provided on both sides of the OTDR 10. Hereinafter, reference numeral "11" is referred to as a first optical connector and reference numeral "12" is referred to as a second optical connector. In the present invention, the optical connectors 21, 11, and 12 may be, for example, FC / APC types.

The first optical connector 11 and the second optical connector 12 may be optically connected. At this time, the first optical connector 11 and the optical connector 21 on the repeater may be optically connected to each other. To this end, the first optical connector 11 and the optical connector 21 on the repeater may have a female / male relationship.

An optical path L1 forming an optical route in an optical network may be connected to the second optical connector 12. Here, the optical path L1 may be an optical path connecting a repeater to a repeater, between a base station and a repeater, and between a base station and a base station.

With the above structure, an optical signal can be transmitted and received between the optical route and the repeater or the base station in the optical network via the OTDR 10. For example, the optical route may use a wavelength of 1330/1570 nm.

The coupler 101 and the first optical switch 102 may be sequentially installed on the connecting optical line R1 between the first optical connector 11 and the second optical connector 12. The first optical switch 102 may be installed between the second optical connector 12 and the optical coupler 101.

The input terminal of the optical coupler 101 may be optically connected to the first optical connector 11, the first output terminal of the two output terminals may be optically connected to the first optical switch 102, and the second output terminal is a WDM filter (103, (Wavelength Division Multiplexing Filter) can be connected to. The optical connector 11 is a preset ratio of the optical signal transmitted by a repeater or a base station (for example, 90 (optical route side): 10 (WDM filter side)) The WDM filter 103 filters signals other than wavelengths that are not used on the optical route, that is, filters noise and filters the filtered optical signals to the PD (105, Photo Diode) via the second optical switch 104. The PD 105 may convert an optical signal into an electrical signal and provide it to a VGA (Variable Gain Amplifier). The VGA 106 converts the amplified signal into an ADC 107 (Analog). to Digital Converter) The ADC 107 converts an analog signal to a digital signal. And it can be provided to the controller 108. The controller 108 may calculate the intensity of the transmitted and received signals on the received digital signal to the light through the moving average calculation (In other words, the optical power).

The control unit 108 may compare the intensity of the transmission / reception signal on the optical path with the reference signal to determine whether the optical signal is normally flowing. If the intensity of the optical signal transmitted / received through the optical route is higher than the reference signal, the control unit 108 may continuously maintain the signal strength monitoring mode and allow the entire system of the OTDR 10 to maintain the signal strength monitoring mode.

Alternatively, if the intensity of the optical signal transmitted / received through the optical route is lower than the reference signal, the control unit 108 may switch to the abnormal point detection mode in order to find an abnormal point on the optical path L1. At this time, the first optical switch 102 and the second optical switch 104 may be switched simultaneously or at this time.

In the signal strength monitoring mode, the first optical switch 102 is switched to connect between the second optical connector 12 and the optical coupler 101 (in this case, the second optical connector 12 and the optical circulator 110 are The first optical switch 102 is optically separated), the second optical switch 104 may be switched to connect the WDM filter 103 and the PD 105 (at this time, the optical circulator 110 is PD (105) and optically separated by the second optical switch (104). Alternatively, in the abnormal point detection mode, the first optical switch 102 is switched to connect between the second optical connector 12 and the optical circulator 110 (at this time, the second optical connector 12 and the connector optical coupler) 101 is optically separated by the first optical switch 102), the second optical switch 104 can be switched to connect the optical circulator 110 and the PD 105 (at this time, WDM filter ( 103) and PD 105 are optically separated by a second optical switch 104).

In the signal strength monitoring mode, the control unit 108 switches to connect the first optical switch 102 to the second optical connector 12 and the optocoupler 101 (at this time, the second optical connector 12 and the optical circuit) The regulator 110 is optically separated by the first optical switch 102), and the second optical switch 104 can be switched to connect the WDM filter 103 and the PD 105 (at this time, the optical circulator) 110 is optically separated by the PD 105 and the second optical switch 104).

In the abnormal point detection mode, the control unit 108 transfers the first optical switch 102 to connect between the second optical connector 12 and the optical circulator 110 (at this time, the second optical connector 12 and The optical coupler 101 is optically separated by the first optical switch 102), and the second optical switch 104 can be switched to connect the optical circulator 110 and the PD 105 (at this time, WDM The filter 103 and PD 105 are optically separated by a second optical switch 104).

When the control unit 108 enters the abnormal point detection mode, the LD driver 112 may be driven to cause the laser diode (LD) 112 to emit a light detection signal. At this time, the control unit 108 transmits a light detection signal to the LD driver 112, and the LD driver 112 drives the LD 111 according to the light detection signal, so that the light detection signal is converted to light, and thus an optical circulator. It may be output to the optical path L1 via the 110 and the first switch 102. The control unit 108 may adjust the arrival distance of the light detection signal by varying the size of the driving power of the LD 112. The designer varies the driving power of the LD 112 according to the optical path length of the detection target section (relay section of the repeater and base station, optical section of the repeater and repeater, optical section of the base station and the base station) to reach the optical detection signal Can be matched to the detection target section. Since only the power source for generating the light detection signal as necessary for the detection target section needs to be generated, the power consumed may be small and it may be manufactured in a smaller size.

The back scattering reflection signal and the rail ray reflection signal, which are generated while the optical detection signal progresses through the optical path, are configured to transmit the second optical connector 12, the first optical switch 102, the optical circulator 110, and the second optical switch 104. It can be delivered to the PD 105 via. At this time, the reflected signal is provided to the control unit 108 via the VGA 106 and the ADC 107, and the control unit 108 measures a cut point or an abnormal point of the optical path L1 using the received reflected signal. can do. The control unit 108 may generate an OTDR trajectory for the entire or near the measured cut or abnormal point.

The control unit 108 may provide optical path status information to an upper node of the optical path monitoring system through the IoT module 130. At this time, the optical signal strength monitoring result in the signal strength monitoring mode (optical signal size information, information on abnormality) and the abnormal point detection result information in the abnormal point detection mode (abnormal point information, OTDR trajectory information on the abnormal point) At least one of them may be provided to the upper node as the optical path state information. The controller 108 may provide the ID of the base station or repeater where the corresponding OTDR is installed to the upper node along with the optical path status information when transmitting the optical path status information. The upper node can use the repeater or base station ID to know exactly at what point and at what point in the optical network an error occurred.

The present invention is not limited to the numerical values of the above-described LD wavelength, pulse width, number of moving averaging, moving averaging time, and LD driving power, and can be varied and applied according to the designer's selection and OTDR application situation.

10: OTDR
101: optocoupler
102: first optical switch
103: WDM filter
104: second optical switch
105: PD
106: VGA
107: ADC
108: control
110: optical circulator
111: LD
112: LD driver

Claims (4)

A first optical connector for optical connection with a repeater or base station; And
And a second optical connector for connection with an optical fiber,
The first optical connector and the second optical connector are optically connected through a connecting optical line,
Further comprising a control unit for monitoring the intensity of the optical signal on the optical path using the optical signal on the connection optical line,
An optical coupler installed on the connection optical line;
A second optical switch installed between the optical coupler and the control unit; And a PD (Photo Diode) installed between the second optical switch and the control unit.
A first optical switch installed between the second optical connector and the optical coupler;
An optical circulator installed between the first optical switch and the second optical switch; And
Further comprising an LD (Laser Diode) installed between the optical circulator and the control unit,
In the signal strength monitoring mode, the control unit switches to connect the first optical switch to the second optical connector and the optical coupler, and to switch the second optical switch to connect the optical coupler to the PD,
In the abnormal point detection mode, the control unit transfers the first optical switch to connect the second optical connector and the optical circulator, and switches the second optical switch to connect the optical circulator and the PD. OTDR.
delete According to claim 1,
In the signal strength monitoring mode, the control unit compares the intensity of the transmission / reception signal on the optical path with a reference signal to determine whether the optical signal is normally flowing, and if the intensity of the optical signal is lower than the reference signal, switches to an abnormal point detection mode Optical path attachment type OTDR, characterized in that performing an operation for finding an abnormal point on the optical path in the abnormal point detection mode. According to claim 1,
Further comprising an IoT module for communication between the control unit and the upper node,
The controller provides the optical path state information to the upper node through the IoT module,
The optical fiber attached type OTDR, characterized in that, along with the optical fiber status information, a base station or repeater ID is provided to an upper node.

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