JP2016163296A - Optical power monitoring device and video communication network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical power monitoring device and a video communication network system that can measure optical power at each wavelength without changing the configuration of the device and a module even if wavelengths get changed.SOLUTION: A V-OLT 20 is an optical power monitoring device for monitoring optical power at each wavelength when light with a plurality of wavelengths is transmitted. It comprises: an FBG 21 consisting of a plurality of fibers with different loss rates; measuring units 22_1, 22_2, 22_3 for measuring the optical power of leakage light after the light goes through each of the plurality of fibers; and a calculation unit 23 for calculating optical power at each wavelength using a prescribed computing expression on the basis of the measurement results of the measuring units 22_1, 22_2, 22_3.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an optical power monitoring apparatus and a video communication network system that monitor optical power of each wavelength when light of a plurality of wavelengths is transmitted in a relay network of the video communication network.

  2. Description of the Related Art Conventionally, a video communication network service composed of a plurality of video system station devices (V-OLT) and subscriber termination devices (V-ONUs) is known. The current video communication network service is provided by one company using one wavelength, and only one wavelength is monitored. In the future, a plurality of operators may provide video communication network services, and another new wavelength may be added.

  Patent Documents 1 and 2 are known as techniques for monitoring optical power.

JP 2008-244664 A JP 2009-290594 A

  As a method of monitoring a plurality of wavelengths when the wavelength used is changed, a method using a duplexer is conceivable (see Patent Document 2). However, according to this method, it is necessary to physically change the configuration of the duplexer and the measurement unit, and it is difficult to quickly respond to service changes and service extensions.

  In view of the above-described conventional technology, the present invention provides an optical power monitoring apparatus and a video communication network system capable of measuring the optical power of each wavelength without changing the configuration of the apparatus / module even when the wavelength is changed. The purpose is to provide.

  In order to achieve the above object, the invention according to the first aspect is an optical power monitoring apparatus that monitors the optical power of each wavelength when light of a plurality of wavelengths is transmitted, from a plurality of fibers having different loss rates. A fiber Bragg grating configured, a measuring unit that measures the optical power of leaked light after transmitting each of the plurality of fibers, and each wavelength using a predetermined arithmetic expression based on the measurement result of the measuring unit And an arithmetic unit for calculating the optical power of the light source.

The invention according to the second aspect is the invention according to the first aspect, wherein the fiber Bragg grating in which k fibers having loss rates of a, b, c,. When different lights P ₁ in, P ₂ in, P ₃ in,..., P _k in are input, the optical powers measured by the k measuring units are P ₁ , P ₂ , P _{3 ,.} and then, ₁ branch index alpha at the junction of each _{fiber, α 2, α 3, ...} , α when the _k, the optical power P ₁ in using a calculation _{formula, P 2 in, P 3 in} , ..., the gist of calculating P _k in.

  In the invention according to the third aspect, in the invention according to the first or second aspect, when any one of the light of a plurality of wavelengths is changed, the arithmetic expression is obtained by an external device connected via a network. The gist of this is to be changed.

  In the invention according to the fourth aspect, in the invention according to any one of the first to third aspects, when any one of the optical powers of the respective wavelengths calculated by the arithmetic unit falls below a threshold value, an active video signal Is switched to a standby video signal.

  In order to achieve the above object, an invention according to a fourth aspect is a video communication network system, the optical power monitoring device according to any one of the first to third aspects, and a plurality of wavelengths transmitted in the video communication network. And a center device that changes an arithmetic expression used in the optical power monitoring device via a network when any one of the wavelengths of the light is changed.

  According to the present invention, it is possible to provide an optical power monitoring device and a video communication network system capable of measuring the optical power of each wavelength without changing the configuration of the device / module even when the wavelength is changed. It is.

1 is a configuration diagram of a video communication network system in an embodiment of the present invention. It is explanatory drawing of the video communication network system in the comparative example 1 (in the case of 1 wavelength). It is explanatory drawing of the video communication network system in the comparative example 2 (in the case of 3 wavelengths). It is explanatory drawing of the video communication network system in the comparative example 3 (in the case of 3 wavelengths). It is explanatory drawing of the video communication network system in the comparative example 3 (in the case of 3 wavelengths). It is explanatory drawing of the video communication network system (in the case of 3 wavelengths) in the Example of this invention. It is a graph which shows the characteristic of FBG used in the Example of this invention. It is explanatory drawing of the example of a calculation (in the case of 3 wavelengths) in the Example of this invention. It is explanatory drawing of the video communication network system (in the case of k wavelength) in the Example of this invention. It is explanatory drawing of the example of a calculation in the Example of this invention (in the case of k wavelength). It is explanatory drawing of the video communication network system (in the case of 3 wavelengths) in the modification of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiment exemplifies a video communication network system for embodying the technical idea of the present invention, and the configuration of the apparatus and the configuration of data are limited to the following embodiment. It is not a thing.
(Video communication network system)
FIG. 1 is a configuration diagram of a video communication network system according to an embodiment of the present invention. As shown in FIG. 1, the video communication network system includes an HE 10, a plurality of V-OLTs 20, and a plurality of V-ONUs 30, and provides video communication network services to users. The HE (broadcaster apparatus) 10 is an apparatus that changes the frequency of the radio wave and sends it out in order to efficiently use various radio waves received by the receiving facility. A V-OLT (video-based in-station accommodation apparatus) 20 amplifies and distributes an optical signal and outputs it to other relay buildings and access sections. A V-ONU (video subscriber termination device) 30 is a device that receives a signal from the V-OLT 20 and converts an optical signal into an electrical signal.

In such a video communication network system, active and standby video signals are transmitted to the V-OLT 20, respectively. The V-OLT 20 measures the received optical power value of the working system, and switches to the standby system when it is determined that the working optical power value is lower than the threshold value.
(Comparative Example 1)
First, a current video communication network system will be described as a comparative example.

FIG. 2 is an explanatory diagram of the video communication network system in the first comparative example. Here, a case where light of one wavelength λ ₁ is transmitted is illustrated. Description will be made assuming that the optical power of the working system is P ₁ and the optical power of the standby system is P ₁ ′.

As shown in this figure, the V-OLT 210 includes measurement units 211 and 213, a determination unit 212, and a switching unit 214. The measuring unit 211 measures the working optical power P ₁ . The determination unit 212 determines whether the optical power P ₁ measured by the measurement unit 211 exceeds a threshold value. When the optical power P ₁ falls below the threshold value, a switching instruction is issued to the switching unit 214 to switch from the active system to the standby system. Thereafter, the standby optical power P ₁ ′ is similarly monitored.

The current video communication network service is provided by one company using one wavelength, and only one wavelength is monitored. In the future, a plurality of operators may provide video communication network services, and another new wavelength may be added.
(Comparative Example 2)
FIG. 3 is an explanatory diagram of the video communication network system in the second comparative example. Here, a case where light of three wavelengths λ ₁ , λ ₂ , and λ ₃ is transmitted is illustrated. Description will be made assuming that the optical power of the working system is P ₁ , P ₂ , P ₃ and the optical power of the standby system is P ₁ ′, P ₂ ′, P ₃ ′.

The measuring unit 221 measures the total value (P ₁ + P ₂ + P ₃ ) of the three active waves. The determination unit 222 determines whether the total value (P ₁ + P ₂ + P ₃ ) of the three waves measured by the measurement unit 221 exceeds a threshold value. When the total value of three waves (P ₁ + P ₂ + P ₃ ) is below the threshold value, a switching instruction is issued to the switching unit 224 to switch from the active system to the standby system. Thereafter, the total value (P ₁ '+ P ₂ ' + P ₃ ') of the three standby waves is monitored in the same manner.

  Thus, according to the comparative example 2, when transmitting a plurality of wavelengths to the video communication network, there is no function of separating the wavelengths, so the total power of the plurality of wavelengths is measured. Therefore, it may be difficult to detect that one optical power has fallen below the threshold value, and there is a possibility that the active system cannot be switched to the standby system in spite of an abnormal state.

This problem will be described by exemplifying the case of three wavelengths. For example, the signal 1 is a signal having a wavelength λ ₁ , a power P ₁ , and a normal power of 10 dBm, and is determined to be normal when the signal is 5 dBm or more. The signal 2 is a signal having a wavelength λ ₂ , a power P ₂ , and a normal power of 8 dBm, and is determined to be normal when the signal is 4 dBm or more. The signal 3 is a signal having a wavelength λ ₃ , a power P ₃ , and a normal power of 6 dBm, and is determined to be normal when the signal is ₃ dBm or more. In addition, it is assumed that the normal value of the normal power of three waves (P ₁ + P ₂ + P ₃ ) is 12 dBm or more, which is half or more of 10 + 8 + 6 = 24 dBm. In such a case, even if P ₁ is 10 dBm (normal), P ₂ is 3 dBm (half or less; abnormal), and P ₃ is 2 dBm (half or less; abnormal), the total value (P ₁ + P ₂ + P ₃ ) Becomes 10 + 3 + 2 = 15 dBm, and is determined to be normal.
(Comparative Example 3)
FIG. 4 is an explanatory diagram of the video communication network system in the third comparative example. Here, a monitoring method using a duplexer will be described. That is, as shown in FIG. 4, the V-OLT 230 includes duplexers 235 and 236 such as AWG (arrayed waveguide). After separating the wavelengths λ ₁ , λ ₂ , λ ₃ using the demultiplexer 235, the optical power P ₁ , P ₂ , P ₂ , P ₂ , λ ₃ of the wavelengths λ ₁ , λ ₂ , λ ₃ is measured using the measuring units 231_1, 231_2, 231_3. It is adapted to measure the P _3.

  The wavelength output from each port of the duplexer 235 (236) is fixed, and when the wavelength to be used is changed, it is necessary to measure the wavelength output from another port. That is, when the wavelength to be used is changed, it is necessary to physically change the connection configuration between the duplexer and the measurement unit. Specifically, it is necessary to change the connection configuration between the duplexer 235 (236) and the measurement units 231_1, 231_2, 231_3 (233_1, 233_2, 233_3), or to exchange with another module in which this connection configuration has been changed. There is.

  On the other hand, there are dozens of buildings in each prefecture where V-OLT20 is installed, and there are thousands of buildings throughout the country. Therefore, when providing new services by changing the wavelength, enormous operation and cost are required. It takes. As an example in which the wavelength is changed, there is a case where a certain service provider ends a service provided at a certain wavelength, and then another service provider starts a service at another wavelength.

For example, as shown in FIG. 5A, it is assumed that service providers A, B, and C originally provided services at λ ₁ , λ ₂ , and λ ₃ . Assume that the service provider A ends the service provided by λ ₁ , and then another service provider D starts the service at another λ ₄ . In this case, as shown in FIG. 5B, the duplexer 235 (236) and the measurement unit 231_1 (233_1) are disconnected, and the duplexer 235 (236), the new measurement unit 231_4 (233_4), and Need to be connected.

As another case where the wavelength is changed, the wavelength used may vary depending on the region. For example, if λ ₁ , λ ₂ , and λ ₃ are used in Osaka and λ ₅ , λ ₆ , and λ ₇ are used in Fukuoka, it is necessary to create modules for Osaka and Fukuoka. Thus, according to the method of creating a module for each region, it is not possible to share parts, and inventory management and the like for new installation and failure handling become complicated.
(Example: 3 wavelengths)
FIG. 6 is an explanatory diagram of the video communication network system in the embodiment of the present invention. Hereinafter, the configuration of the video communication network system according to the embodiment of the present invention will be described focusing on differences from the comparative example.

  The V-OLT 20 is an optical power monitoring apparatus that monitors the optical power of each wavelength when light of a plurality of wavelengths is transmitted in the video communication network. The VBG 21 (26) and the measurement units 22_1, 22_2, 22_3 (27_1). 27_2, 27_3), a calculation unit 23, a determination unit 24, and a switching unit 25. The FBG 21 (26) is a fiber Bragg grating composed of a plurality of fibers having different loss rates. The measurement units 22_1, 22_2, and 22_3 (27_1, 27_2, and 27_3) are measuring devices that measure the optical power of the leaked light after being transmitted through each fiber of the FBG 21 (26). The calculation unit 23 calculates the optical power of each wavelength using a predetermined calculation formula based on the measurement results of the measurement units 22_1, 22_2, and 22_3 (27_1, 27_2, and 27_3). The determination unit 24 issues a switching instruction to the switching unit 25 when any of the optical power of each wavelength calculated by the calculation unit 23 falls below the threshold value. Upon receiving a switching instruction from the determination unit 24, the switching unit 25 switches the active video signal to the standby video signal.

  The center S is a device connected to the V-OLT 20 via a network. The center S sends an arithmetic expression (determinant) to the V-OLT 20 when any of the wavelengths of light transmitted in the video communication network is changed, and the arithmetic expression in the V-OLT 20 is change. That is, the software (determinant) of the calculation unit 23 of the V-OLT 20 can be changed.

  FIG. 7 is a graph showing the characteristics of the FBG 21 (26) used in the example of the present invention. The FBG 21 is composed of three fibers A, B, and C having different loss rates. As shown in FIG. 7, in the case of the fiber A, the loss rate of the wavelength X is a1, the loss rate of the wavelength Y is a2, and the loss rate of the wavelength Z is a3. In the case of the fiber B, the loss rate of the wavelength X is b1, the loss rate of the wavelength Y is b2, and the loss rate of the wavelength Z is b3. In the case of the fiber C, the loss rate of the wavelength X is c1, the loss rate of the wavelength Y is c2, and the loss rate of the wavelength Z is c3. In this way, fibers with different loss rates are prepared for incident light (X, Y, Z), and the leakage light is measured to obtain the values (a, b, c).

  FIG. 8 is an explanatory diagram of a calculation example (in the case of three wavelengths) in the embodiment of the present invention. As preconditions, the loss rate of the fiber used and the wavelength to be transmitted are known. The number of wavelengths is equal to or less than the number of fibers having different loss rates.

First, light P ₁ in, P ₂ in, and P ₃ in having different powers are input to the FBG 21 in which three different fibers 21a, 21b, and 21c having loss rates a, b, and c are connected in multiple stages. Connection point of the fibers is connected to the measurement section 22_1,22_2,22_3, the optical power measured by the measuring unit 22_1,22_2,22_3 and _{P 1, P 2, P 3} .

The formula at this time is shown below. Here, α ₁ , α ₂ , and α ₃ are branch rates at the connection points of the fibers 21a, 21b, and 21c. As a branching method, there are a method using an optical coupler, a leaked light when a fiber is bent, and the like.

  This formula is expressed as a matrix as follows.

Since P ₁ in, P ₂ in, and P ₃ in can be calculated by processing the inverse matrix A ^-1 by the calculation unit 23, it is possible to measure optical power of a plurality of wavelengths.

Further, when the wavelength is changed, the center S is the loss rate a modified wavelength, b, by measuring c calculates a new inverse matrix B ^-1, notifies the B ^-1 to V-OLT 20 To do. Receiving this notification, the computing unit 23 of the V-OLT 20 registers a new inverse matrix B ⁻¹ instead of the inverse matrix A ⁻¹ . As a result, when λ ₁ , λ ₂ , and λ ₃ are used, the inverse matrix in the V-OLT 20 can be changed from the center S even when λ ₁ is changed to λ _4. It is possible to measure the optical power of a plurality of wavelengths without changing the.
(Example: k wavelength)
Next, the case of k wavelength will be described. When the number of wavelengths is k, k fibers having different loss rates and k measurement units corresponding to the respective fibers may be provided. The number of fibers and measuring units is not particularly limited as long as it is k or more. Other points are basically the same as in the case of three wavelengths as described below.

That is, as shown in FIG. 9 and FIG. 10, the power is different in the FBG 21 in which k different fibers 21a, 21b, 21c,..., 21n having loss rates a, b, c,. Lights P ₁ in, P ₂ in, P ₃ in,..., P _k in are input. Fiber connection points measuring unit 22_1,22_2,22_3, ..., are connected to 22_K, measuring unit 22_1,22_2,22_3, ..., P ₁ the optical power measured by _{22_k, P 2, P 3,} ..., P _k .

The formula at this time is shown below. Here, α ₁ , α ₂ , α ₃ ,..., Α _k are branch rates at the connection points of the fibers 21a, 21b, 21c,. As a branching method, there are a method using an optical coupler, a leaked light when a fiber is bent, and the like.

  This formula is expressed as a matrix as follows.

Since P ₁ in, P ₂ in, P ₃ in,..., P _k in can be calculated by processing the inverse matrix X ⁻¹ in the arithmetic unit 23, measuring the optical power of a plurality of wavelengths. Is possible.

When the wavelength is changed, the center S measures the loss rates a, b, c,..., N of the changed wavelength, calculates a new inverse matrix Y ^−1, and converts this Y ⁻¹ to V -Notify OLT20. Receiving this notification, the computing unit 23 of the V-OLT 20 registers a new inverse matrix Y ⁻¹ instead of the inverse matrix X ⁻¹ . Thereby, even when λ _k is changed to λ _m when λ ₁ , λ ₂ , λ ₃ ,..., Λ _k are used, the inverse matrix in the V-OLT 20 is changed from the center S. Therefore, it is possible to measure the optical power of a plurality of wavelengths without changing the apparatus.
(Modification)
FIG. 11 is an explanatory diagram of a video communication network system in a modification of the present invention. The difference from FIG. 6 is the arrangement of the FBG 21 (26). That is, as shown in FIG. 11, the light input to the V-OLT 20 may directly enter the FBG 21 and the light that has passed through the FBG 21 may directly enter the switching unit 25. That is, according to the configuration of FIG. 11, the optical power can be transmitted to the V-ONU 30 without loss, so that the quality of the video signal can be maintained as compared with the configuration of FIG.

  On the other hand, according to the configuration of FIG. 6, the FBG 21 and the measurement units 22_1, 22_2, and 22_3 can be configured as one measuring instrument module. This measuring instrument module does not exist on the path connecting the switching unit 25 from the input port of the V-OLT 20. Therefore, even when any of the measurement units 22_1, 22_2, and 22_3 fails, the measuring instrument module can be replaced without affecting the video signal path. There is a similar merit when the measuring instrument module is replaced because the number of wavelengths used increases.

  As described above, the V-OLT 20 according to the embodiment of the present invention is an optical power monitoring apparatus that monitors the optical power of each wavelength when light of a plurality of wavelengths is transmitted, and a plurality of fibers having different loss rates. Based on the measurement results of the measurement units 22_1, 22_2, and 22_3, and the measurement units 22_1, 22_2, and 22_3 that measure the optical power of the leaked light after being transmitted through each of the plurality of fibers. And a calculation unit 23 that calculates the optical power of each wavelength using the. Therefore, even when the wavelength is changed, the optical power of each wavelength can be measured without changing the configuration of the apparatus / module. This eliminates the need to change thousands of V-OLT devices nationwide, and can reduce the time and cost of changing each device. In addition, even when the wavelength used in each region, such as Osaka and Fukuoka, is different, it is possible to share devices and modules. As a result, it is possible to reduce the cost of goods at the time of system construction, and to reduce the cost by using a common spare article for failure.

Specifically, light P ₁ in, P ₂ in, P ₃ in,..., P _{k having} different powers are connected to an FBG 21 in which k fibers having loss rates of a, b, c,. when you enter in, k-number of the measurement unit 22_1,22_2,22_3, ..., P ₁ optical power 22_k was _{measured, P 2, P 3, ...} , and P _k, a branch ratio at the junction of each fiber the _{α 1, α 2, α 3} , ..., when the alpha _k, the optical power P ₁ in using a calculation _{formula, P 2 in, P 3 in} , ..., and calculate the P _k in Good. Thereby, even when the number of wavelengths is k, it is possible to measure the optical powers P ₁ in, P ₂ in, P ₃ in,..., P _k in of each wavelength.

  Further, when any one of the wavelengths of light is changed, the arithmetic expression may be changed by the center S connected via the network. As a result, an arithmetic expression can be obtained on the center S side and notified to the V-OLT 20, so that the arithmetic expression used in the V-OLT 20 can be changed quickly and easily.

  Further, when any one of the optical powers of the respective wavelengths calculated by the calculation unit 23 falls below the threshold value, the active video signal may be switched to the standby video signal. As a result, when any of the optical powers of the working system falls below the threshold value, the standby system is switched over, so that a stable video communication network service can be realized.

  In the above description, when any of the optical powers of the respective wavelengths calculated by the calculation unit 23 falls below the threshold value, the active video signal is switched to the standby video signal. It is not limited to this. That is, there are various methods of using the optical power of each wavelength calculated by the calculation unit 23, and it can be changed as appropriate.

  In addition, the present invention can be realized not only as the V-OLT 20, but also as an optical power monitoring method using the characteristic processing unit included in the V-OLT 20 as each step, or executing each step in a computer. It can also be realized as an optical power monitoring program. It goes without saying that such a program can be distributed via a recording medium such as a CD-ROM or a transmission medium such as the Internet.

10 ... HE
20 ... V-OLT (Optical power monitoring device)
21 (26) ... FBG
22_1, 22_2, 22_3 (27_1, 27_2, 27_3) ... measurement unit 23 ... calculation unit 24 ... determination unit 25 ... switching unit 30 ... V-ONU
S ... Center (center equipment)

Claims (5)

An optical power monitoring device that monitors the optical power of each wavelength when multiple wavelengths of light are transmitted,
A fiber Bragg grating composed of multiple fibers with different loss rates;
A measurement unit for measuring the optical power of the leaked light after transmitting each of the plurality of fibers;
An optical power monitoring apparatus comprising: an arithmetic unit that calculates optical power of each wavelength using a predetermined arithmetic expression based on a measurement result of the measurement unit. The optical fiber P ₁ in, P ₂ in, P ₃ in,..., P _{k is} connected to the fiber Bragg grating in which k fibers having loss rates of a, b, c _,. When in is input, the optical powers measured by the k measuring units are P ₁ , P ₂ , P ₃ ,..., P _k, and the branching rates at the connection points of the fibers are α ₁ , α ₂ , α _3, ..., alpha when the _k, the optical power P ₁ in using a calculation _{formula, P 2 in, P 3 in} , ..., according to claim 1, characterized in that to calculate the P _k in Optical power monitoring device.

  3. The optical power monitoring according to claim 1, wherein when any one of a plurality of wavelengths of light is changed, the arithmetic expression is changed by an external device connected via a network. apparatus.   The active video signal is switched to a standby video signal when any one of the optical powers of the respective wavelengths calculated by the calculation unit falls below a threshold value. The optical power monitoring device described in 1. The optical power monitoring device according to any one of claims 1 to 4,
A center device that changes an arithmetic expression used in the optical power monitoring device via the network when any of the wavelengths of light transmitted in the video communication network is changed. Video communication network system.

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