JP5863750B2 - Broadcast system and center device - Google Patents

Description

  The present invention relates to a broadcasting system and a center device.

  FIG. 9 shows a typical system configuration of a broadcasting service using a 1-to-N optical transmission path typified by the FTTH (Fiber To The Home) system. In this example, the broadcast signal is converted into light in the optical transmitter 1a of the center apparatus 1 arranged at the broadcaster's station or the like, which is the transmission line start point, the light is amplified in the optical amplifier 1b, and the optical coupler 1c After being distributed, it is sent to the optical transmission line 2. The light transmitted to the optical transmission line 2 passes through the higher-order optical transmission line 2a, and then is distributed by the optical couplers 2b-1 to 2b-m arranged in the closure, and is arranged in the subscriber's home. 3-1 to 3-n are reached.

  It is necessary for a business operator who develops a broadcasting service to prevent a broadcast from being interrupted due to a failure of the optical transmitter 1a or the optical amplifier 1b or a failure of the optical transmission path 2 and the like, which is directly connected to the suspension of the service.

  FIG. 10 shows that the optical transmitters 1a-1, 1a-2 and the optical amplifiers 1b-1, 1b-2 are provided in two systems, respectively, and the distributor 1d is provided to distribute the broadcast signal into two parts. FIG. 3 shows a configuration in which redundancy is achieved by selecting one of the two systems. According to such a configuration, even when one of the two systems fails, the service can be prevented from being stopped by selecting the other.

  On the other hand, since the optical transmission line 2 is a 1-to-N type optical transmission line, it is expensive to duplex the fiber to the optical terminal device. However, the upper side optical transmission line 2a is highly important because a failure may affect all subsequent subscribers, but the upper side optical transmission line 2a is passive (having a power supply). Therefore, it is difficult to achieve redundancy.

  As a technique for making such an upper side optical transmission line redundant, there is a technique shown in Patent Document 1. In the technique disclosed in Patent Document 1, the optical transmission line 120 is made redundant by two optical fibers 121 and 122 as shown in FIG. The light transmitted through the optical fibers 121 and 122 is distributed to the optical receiver 131 and the optical coupler 125 by the optical coupler 124. The light incident on the optical coupler 125 is returned to the center device 110 via the optical fibers 121 and 122 as return light. In the center apparatus 110, as shown in FIG. 12, the return light is converted into electric signals by the photoelectric conversion units (O / E) 141 and 142, respectively, and the control unit 143 detects the intensity of the return light based on the electric signals. In addition, an optimal transmission path can be selected by selecting the transmission path with the larger intensity of the return light by controlling the switch unit 144.

JP 2009-206565 A

  By the way, in the technique disclosed in Patent Document 1, two optical fibers corresponding to the vertical direction are used for each transmission line in order to use the same light as the light transmitted from the center device 110 (downlink light) as the return light. There is a problem that the cost is high.

  Also, since separate optical fibers are used, for example, even if an abnormality occurs in the optical fiber for downstream light, there may be no abnormality in the optical fiber for return light. There is also a problem that it is difficult to reliably detect.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a broadcasting system and a center apparatus that can more reliably detect an optical fiber abnormality without incurring an increase in cost. It is said.

In order to solve the above-described problems, the present invention provides a broadcasting system in which a broadcast signal is transmitted by light from a center device to a plurality of optical terminal devices via a redundant optical fiber. A transmitting unit that transmits an optical signal to an optical fiber; a receiving unit that receives the reflected light that is reflected and returned from the active optical fiber out of the optical signal transmitted from the transmitting unit; and the receiving unit Detecting the occurrence of a failure in the active optical fiber from the change in the intensity of the reflected light received by the detector, and detecting the occurrence of a failure in the active optical fiber by the detecting means Switching means for switching to the optical fiber in the standby system, and the detection means is in a state where the intensity of the reflected light exceeds a predetermined threshold for a predetermined time It said detected as occurrence of a fault in the working system of the optical fiber, detected when the intensity of the reflected light is not continued for the predetermined period of time even when it exceeds a predetermined threshold as a generation of a fault in the optical fiber of the active system is The predetermined time is several seconds or more .
According to such a configuration, it is possible to more reliably detect an abnormality in the optical fiber without causing an increase in cost.

Further, the present invention is characterized in that the predetermined time is several seconds .

Further, the present invention is characterized in that the transmission means transmits the broadcast signal as the optical signal to the working optical fiber.
According to such a configuration, it is possible to detect an optical fiber abnormality without complicating the configuration of the apparatus by performing detection using a broadcast signal.

Further, the present invention is characterized in that the transmission means transmits an optical signal having a wavelength different from that of the broadcast signal to the working optical fiber.
According to such a configuration, by using a wavelength different from that of the broadcast signal, loss of reflected light can be reduced and detection with high sensitivity can be realized.

According to another aspect of the present invention, there is provided a mixing unit that mixes light transmitted through the active and standby optical fibers, and a distribution unit that distributes the light mixed by the mixing unit and supplies the mixed light to the plurality of optical terminal devices. And a standby reception means for receiving the reflected light of the standby optical fiber, and the detection means changes when the light intensity of the reflected light received by the standby reception means changes. Is characterized in that it is determined that a failure has occurred in the optical fiber subsequent to the distributing means.
According to such a configuration, it is possible to detect disconnection of the optical fiber that occurs at a later stage than the distribution means.

The present invention also provides an optical signal transmitted from the center device to a plurality of optical terminal devices via a redundant optical fiber, wherein the center device of the broadcasting system transmits an optical signal to the active optical fiber. Transmitting means, receiving means for receiving reflected light returning from the active optical fiber, out of the optical signals transmitted from the transmitting means, and reflected light received by the receiving means Detection means for detecting the occurrence of a failure in the working optical fiber from a change in intensity; and when the occurrence of a failure is detected in the working optical fiber by the detecting means, the standby optical fiber Switching means for switching to the active optical fiber when the state in which the intensity of the reflected light exceeds a predetermined threshold continues for a predetermined time. Detected as occurrence of a fault in bus, the intensity of the reflected light is not detected as occurrence of a fault in the optical fiber of the active system when they are not continued for a predetermined period of time even if it exceeds a predetermined threshold, the predetermined Time is several seconds or more .
According to such a configuration, it is possible to more reliably detect an abnormality in the optical fiber without causing an increase in cost.

Further, the present invention is a broadcast system for transmitting a broadcast signal by light from a center device to a plurality of optical terminal devices via a redundant optical fiber, and mixing light transmitted through an active optical fiber and a standby optical fiber. And a distribution unit that distributes the light mixed by the mixing unit and supplies the mixed light to the plurality of optical terminal devices, and the center device sends an optical signal to the optical fiber of the working system. Transmitting means for transmitting; receiving means for receiving reflected light that is reflected and returned from the active optical fiber out of the optical signals transmitted from the transmitting means; and reflected light received by the receiving means Detection means for detecting the occurrence of a failure in the working optical fiber, and standby system receiving means for receiving the reflected light of the standby optical fiber, from the intensity change of The detecting means, when the light intensity of the reflected light received by the backup system reception means is changed, it is determined that the subsequent stage of the optical fiber than the distribution means fails, it is characterized.
According to such a configuration, it is possible to more reliably detect an abnormality in the optical fiber without causing an increase in cost.
The present invention also provides a broadcasting system for transmitting a broadcast signal by light from a center apparatus to a plurality of optical terminal apparatuses via a redundant optical fiber, wherein the optical signal transmitted through the active and standby optical fibers is transmitted. In the center device of the broadcasting system, the mixing device for mixing the light mixed by the mixing device and supplying the mixed light to the plurality of optical terminal devices. Transmitting means for transmitting an optical signal, receiving means for receiving reflected light returning from the active optical fiber among the optical signals transmitted from the transmitting means, and received by the receiving means Detection means for detecting the occurrence of a failure in the active optical fiber from the change in intensity of the reflected light, and standby reception for receiving the reflected light of the standby optical fiber And when the light intensity of the reflected light received by the standby-system receiving means has changed, the detecting means determines that a failure has occurred in the optical fiber subsequent to the distributing means. It is characterized by.
According to such a configuration, it is possible to more reliably detect an abnormality in the optical fiber without causing an increase in cost.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the broadcasting system and center apparatus which can detect the abnormality of an optical fiber more reliably, suppressing the increase in cost compared with the past.

It is a figure which shows the structural example of the broadcasting system which concerns on 1st Embodiment of this invention. It is a figure for demonstrating the temporal change of reflected light. It is a flowchart for demonstrating the operation | movement at the time of the operation start of 1st Embodiment shown in FIG. It is a flowchart for demonstrating the operation | movement at the time of operation | movement of 1st Embodiment shown in FIG. It is a figure which shows the structural example of the broadcast system which concerns on 2nd Embodiment of this invention. It is a figure which shows the structural example of the broadcast system which concerns on 3rd Embodiment of this invention. It is a figure which shows the structural example of the broadcast system which concerns on 4th Embodiment of this invention. It is a figure which shows the structural example of the broadcasting system which concerns on 5th Embodiment of this invention. It is a figure which shows the structure of the conventional broadcast system. It is a figure which shows the structure of the conventional broadcast system. It is a figure which shows the structure of the conventional broadcast system. It is a figure which shows the detailed structure of light SW shown in FIG.

  Next, an embodiment of the present invention will be described.

(A) 1st Embodiment FIG. 1: is a figure which shows the structural example of the broadcasting system which concerns on 1st Embodiment of this invention. As shown in FIG. 1, the broadcasting system according to the first embodiment of the present invention includes a center device 10, an optical transmission line 20, a closure 30, and an optical terminal device group 40.

  The center device 10 is disposed, for example, in a broadcaster's office or the like, converts a broadcast signal into an optical signal, and transmits the optical signal to the optical transmission line 20. The optical transmission line 20 includes redundant optical fibers 21 and 22, and one of the optical fibers 21 and 22 is used as a working system, and the other is used as a standby system. The closure 30 includes, for example, a coupler 31, and mixes and distributes optical signals transmitted via the optical fibers 21 and 22 and outputs them to the optical terminal device group 40. The optical terminal device group 40 includes a plurality of optical terminal devices 40-1 to 40-n. Each of the optical terminal devices 40-1 to 40-n is configured by a V-ONU (Video Optical Network Unit) or the like installed in each subscriber's house, receives an optical signal, converts it into an electrical signal, and transmits a broadcast signal. Output as.

  Here, the center apparatus 10 includes transmission units 11 and 12 with optical ON / OFF functions, reflected light detection units 13 and 14, and couplers 15 and 16. The transmission unit 11 with the optical ON / OFF function converts the broadcast signal into an optical signal and outputs the optical signal to the coupler 15. Further, the transmitter 11 with the light ON / OFF function turns on or off the output of the optical signal according to the detection result of the reflected light by the reflected light detector 13. Similarly, the transmission unit 12 with the optical ON / OFF function converts the broadcast signal into an electrical signal and outputs the optical signal to the coupler 16. The transmission unit 12 with the light ON / OFF function turns on or off the output of the optical signal according to the detection result of the reflected light by the reflected light detection unit 14. The transmission units 11 and 12 with the optical ON / OFF function have a redundant configuration, and either one operates and the other stops.

  The reflected light detection unit 13 converts the reflected light generated by the failure (for example, disconnection of the optical fiber 21) generated in the optical fiber 21 from the optical signal transmitted from the transmission unit 11 with the optical ON / OFF function into an electrical signal. Then, it is supplied to the transmitter 11 with the optical ON / OFF function. The reflected light detection unit 14 converts the reflected light generated by the failure generated in the optical fiber 22 out of the optical signal transmitted from the transmission unit 12 with the optical ON / OFF function into an electrical signal, and transmits with the optical ON / OFF function. To the unit 12. The coupler 15 outputs the optical signal supplied from the transmitter 11 with the optical ON / OFF function to the optical fiber 21 and supplies the reflected light transmitted through the optical fiber 21 to the reflected light detector 13. The coupler 16 outputs the optical signal supplied from the transmission unit 12 with the optical ON / OFF function to the optical fiber 22 and supplies the reflected light transmitted through the optical fiber 22 to the reflected light detection unit 14.

  Next, the operation of the first embodiment will be described. For example, when the optical fiber 21 is set as the active system and the optical fiber 22 is set as the standby system, the transmitter 11 with the optical ON / OFF function outputs an optical signal obtained by converting the broadcast signal to the coupler 15. . On the other hand, the transmission unit 12 with the optical ON / OFF function turns off the output of the optical signal. The coupler 15 sends the optical signal output from the transmitter 11 with the optical ON / OFF function to the optical fiber 21. When the optical fiber 21 is normal, the optical signal transmitted through the optical fiber 21 is distributed by the coupler 31 and supplied to the optical terminal devices 40-1 to 40-n.

  Even when the optical fiber 21 is normal, a part of the optical signal transmitted through the optical fiber 21 is reflected and enters the coupler 15 as reflected light. The reflected light incident on the coupler 15 is incident on the reflected light detector 13. The reflected light detection unit 13 converts the reflected light into an electrical signal and supplies the electrical signal to the transmission unit 11 with a light ON / OFF function.

  FIG. 2A shows a case where the optical fiber 21 is normal and shows a temporal change in the intensity of reflected light when the state of the optical fiber 21 does not change (for example, when no physical force is applied). FIG. When the optical fiber 21 is normal and the state does not change, the light intensity of the reflected light is L and does not change with time. Further, the threshold Th is not exceeded. The threshold value Th can be set to about several times (for example, twice) the normal light intensity L. Of course, other values may be used.

  FIG. 2B shows a case where the optical fiber 21 is normal, and the reflection when the state changes (for example, when a physical force is applied to the optical fiber 21 (when it is shaken by the influence of wind)). It is a figure which shows the time change of the intensity | strength of light. When the optical fiber 21 is normal and the state changes, the light intensity of the reflected light changes around L, but does not exceed the threshold Th. In FIG. 2B, the state changes at timings t1 to t2.

  FIG. 2C is a diagram illustrating a temporal change in the intensity of the reflected light when a failure occurs in the optical fiber 21 (for example, when the optical fiber 21 is disconnected). When the optical fiber 21 is disconnected, the optical signal is reflected by, for example, about 3% at the disconnected end surface. As a result, the light intensity of the reflected light greatly changes before and after the disconnection occurs. FIG. 2C shows a state where the optical fiber 21 is disconnected at the timing t3. As shown in this figure, when the optical fiber 21 is disconnected at the timing t3, the light intensity of the reflected light increases to a level exceeding the threshold value Th, and thereafter, a substantially constant state is maintained.

  The reflected light detector 13 detects a change in the intensity of the reflected light as shown in FIG. 2C and notifies the transmitter 11 with the light ON / OFF function. When the intensity of the reflected light changes to a level exceeding the threshold value Th, the transmission unit 11 with the optical ON / OFF function determines that a break has occurred in the optical fiber 21 and turns off the generation of the optical signal. At the same time, the transmission unit 12 with the optical ON / OFF function is notified that the disconnection has occurred in the working optical fiber 21. As a result, the transmission unit 12 with the optical ON / OFF function starts an operation of converting the broadcast signal into an optical signal and outputting the optical signal to the coupler 16. The coupler 16 transmits the optical signal supplied from the transmitter 12 with the optical ON / OFF function to the coupler 31 through the optical fiber 22. The coupler 31 distributes the optical signal and supplies it to the optical terminal devices 40-1 to 40-n. As a result, even if a disconnection occurs in the working optical fiber 21, it is possible to switch to the standby optical fiber 22 and continue broadcasting, thereby avoiding the occurrence of waves.

  Next, processing executed in the first embodiment shown in FIG. 1 will be described with reference to FIGS. 3 and 4.

  FIG. 3 is a diagram illustrating an example of processing executed when the operation of the first embodiment is started. When the process shown in this figure is started, the following steps are executed.

  In step S10, the center apparatus 10 starts transmission by the active system. For example, when the transmission unit 11 with the optical ON / OFF function is set to the active system, the transmission unit 11 with the optical ON / OFF function starts transmitting an optical signal. At this time, the standby transmission is stopped.

  In step S <b> 11, the working reflected light detection unit detects the intensity of the reflected light. For example, when the transmitter 11 with the optical ON / OFF function is set to the active system, the reflected light detector 13 detects the intensity of the reflected light transmitted through the optical fiber 21.

  In step S12, the active transmission unit with the optical ON / OFF function stores the intensity of the detected reflected light. For example, when the transmission unit 11 with the optical ON / OFF function is set to the active system, the transmission unit 11 with the optical ON / OFF function stores a value indicating the intensity of the reflected light detected by the reflected light detection unit 13. To do.

  In step S <b> 13, the active transmission unit with optical ON / OFF function calculates and stores a threshold value Th <b> 1 (see Th in FIG. 2C) for determining whether or not a disconnection has occurred. For example, when the transmission unit 11 with the optical ON / OFF function is set to the active system, a value obtained by multiplying the value indicating the intensity of the reflected light stored in step S12 by several times (for example, twice) is set as the threshold Th1. Remember as. Of course, a value obtained by adding a predetermined value to the value indicating the intensity of the reflected light stored in step S12 may be set as the threshold Th1.

  In step S14, when the active system is transmitting, the reflected light detection unit of the standby system detects the intensity of the reflected light. For example, when the transmission unit 12 with the optical ON / OFF function is set to the standby system, the reflected light detection unit 14 detects the intensity of the reflected light transmitted through the optical fiber 22.

  In step S15, the standby transmission unit with the light ON / OFF function stores a value indicating the intensity of the detected reflected light. For example, when the transmission unit 12 with the optical ON / OFF function is set as a standby system, the transmission unit 12 with the optical ON / OFF function stores a value indicating the intensity of the reflected light detected by the reflected light detection unit 14. To do.

  In step S <b> 16, the standby transmission unit with optical ON / OFF function calculates and stores a threshold value Th <b> 2 for determining whether or not a disconnection has occurred. For example, when the transmission unit 12 with the optical ON / OFF function is set to the standby system, a value obtained by multiplying the value indicating the intensity of the reflected light stored in step S15 by several times (for example, twice) is set as the threshold Th2. Remember as. Of course, a value obtained by adding a predetermined value to the value indicating the intensity of the reflected light stored in step S15 may be set as the threshold Th2. The threshold value Th2 is a threshold value for detecting a disconnection after the coupler 31, as will be described later.

  In step S <b> 17, the center apparatus 10 stops transmission on the active system and starts transmission on the standby system. For example, when the transmission unit 11 with the optical ON / OFF function is set to the active system and the transmission unit 12 with the optical ON / OFF function is set to the standby system, the operation of the transmission unit 11 with the optical ON / OFF function is stopped. The transmission of the transmission unit 12 with the optical ON / OFF function is started.

  In step S18, the reflected light detection unit of the standby system detects the intensity of the reflected light. For example, when the transmission unit 12 with the optical ON / OFF function is set to the standby system, the reflected light detection unit 14 detects the intensity of the reflected light transmitted through the optical fiber 22.

  In step S19, the standby transmission unit with light ON / OFF function stores a value indicating the intensity of the detected reflected light. For example, when the transmission unit 12 with the optical ON / OFF function is set as a standby system, the transmission unit 12 with the optical ON / OFF function stores a value indicating the intensity of the reflected light detected by the reflected light detection unit 14. To do.

  In step S20, the standby transmission unit with optical ON / OFF function calculates and stores a threshold Th3 (see Th in FIG. 2C) for determining whether or not a disconnection has occurred. For example, when the transmission unit 12 with the optical ON / OFF function is set to the standby system, a value obtained by multiplying the value indicating the intensity of the reflected light stored in step S19 by several times (for example, twice) is set as the threshold Th3. Remember as. Of course, the threshold Th3 may be a value obtained by adding a predetermined value to the value indicating the intensity of the reflected light stored in step S19.

  In step S21, when the standby system is transmitting, the reflected light detector of the active system detects the intensity of the reflected light. For example, when the transmitter 11 with the optical ON / OFF function is set to the active system, the reflected light detector 13 detects the intensity of the reflected light transmitted through the optical fiber 21.

  In step S <b> 22, the active transmission unit with optical ON / OFF function stores a value indicating the intensity of the detected reflected light. For example, when the transmission unit 11 with the optical ON / OFF function is set to the active system, the transmission unit 11 with the optical ON / OFF function stores a value indicating the intensity of the reflected light detected by the reflected light detection unit 13. To do.

  In step S <b> 23, the active transmission unit with optical ON / OFF function calculates and stores a threshold Th <b> 4 for determining whether or not a disconnection has occurred. For example, when the transmitter 11 with the optical ON / OFF function is set to the active system, a value obtained by multiplying the value indicating the intensity of the reflected light stored in step S22 by several times (for example, twice) is set as the threshold Th4. Remember as. Of course, a value obtained by adding a predetermined value to the value indicating the intensity of the reflected light stored in step S22 may be set as the threshold Th4. The threshold value Th4 is a threshold value for detecting a disconnection after the coupler 31, as will be described later.

  In step S24, transmission by the active system is started. For example, when the transmission unit 11 with the optical ON / OFF function is set to the active system, the transmission unit 12 with the optical ON / OFF function stops transmission of the signal and the transmission unit 11 with the optical ON / OFF function. Starts transmitting signals.

  With the above processing, the intensity of the reflected light and the threshold values Th1 and Th2 when transmitted by the active system, and the intensity of the reflected light and the threshold values Th3 and Th4 when transmitted by the standby system are the active system and the standby system. Are stored in the transmission unit with the optical ON / OFF function.

  Next, with reference to FIG. 4, processing executed up to step S24 in FIG. 3 and executed when the system is operated will be described. When the process shown in FIG. 4 is started, the following steps are executed.

  In step S30, the reflected light detector of the active system detects the intensity of the reflected light and supplies it to the transmitter with the light ON / OFF function. For example, when the transmission unit 11 with the optical ON / OFF function is an active system, the reflected light detection unit 13 converts the reflected light transmitted through the optical fiber 21 into an electrical signal, and transmits the electrical signal to the transmission unit 11 with the optical ON / OFF function. Supply.

  In step S31, the transmission unit with the active optical ON / OFF function determines whether or not the intensity of the reflected light has changed. If it is determined that the intensity has changed (step S31: Yes), the process proceeds to step S32. In other cases (step S31: No), the process returns to step S30 and the same processing is repeated. For example, when the transmitter 11 with the light ON / OFF function is an active system, when it is determined that the intensity of the reflected light detected by the reflected light detector 13 has changed, the process proceeds to step S32.

  In step S32, the transmission unit with the active optical ON / OFF function determines whether or not the state in which the intensity of the reflected light exceeds the threshold value Th1 has continued for a certain period of time, and determines that it has continued for a certain period of time. In the case (step S32: Yes), the process proceeds to step S33. In other cases (step S32: No), the process returns to step S30 and the same process as described above is repeated. For example, when the transmission unit 11 with the optical ON / OFF function is an active system, the state where the intensity of the reflected light detected by the reflected light detection unit 13 exceeds the threshold Th1 continues for a certain time (for example, several seconds) or more. Proceed to step S33. The threshold value Th1 is the threshold value of the reflected light that is transmitted through the optical fiber 21 during operation by the active system, calculated in step S13 in FIG.

  In step S33, the center apparatus 10 detects the intensity of the reflected light of the standby system. For example, when the transmission unit 12 with the optical ON / OFF function is set to the standby system, the reflected light detection unit 14 detects the intensity of the reflected light transmitted through the optical fiber 22.

  In step S34, the center apparatus 10 determines whether or not the state in which the intensity of the reflected light of the standby system detected in step S33 exceeds the threshold Th2 calculated in step S16 in FIG. 3 continues. When it determines with continuing (step S34: Yes), it progresses to step S35, and when that is not right (step S34: No), it progresses to step S36. More specifically, when the active optical fiber 21 is disconnected, the reflected light is transmitted back through only the optical fiber 21, but is reflected when the optical fiber after the coupler 31 is disconnected. Light is transmitted not only to the optical fiber 21 but also to the optical fiber 22. For example, when the optical fiber between the coupler 31 and the optical terminal device 40-1 is disconnected, the reflected light is distributed by the coupler 31 and introduced into the optical fibers 21 and 22. Is transmitted to the couplers 15 and 16. For this reason, when both the intensity of the reflected light detected by the reflected light detection unit 13 and the reflected light detection unit 14 increases, it can be determined that the disconnection is after the coupler 31, and in this case, the process proceeds to step S35. . On the other hand, if the intensity of the reflected light detected by the reflected light detection unit 14 has not increased (if the threshold value Th2 or less), it is determined that the working optical fiber 21 is disconnected, and the process proceeds to step S36.

  In step S35, the center apparatus 10 determines that a failure such as a disconnection has occurred after the coupler 31, and issues a warning, for example. At this time, the switching operation between the active system and the standby system is not performed.

  In step S36, processing for switching between the active system and the standby system is executed. For example, when the transmission unit 11 with the optical ON / OFF function is an active system, the transmission unit 11 with the optical ON / OFF function is turned off and the transmission unit 12 with the optical ON / OFF function is turned on.

  In step S37, the center apparatus 10 starts transmission of a broadcast signal by a new active system. For example, when the transmission unit 12 with the optical ON / OFF function is newly used, the transmission of the broadcast signal by the transmission unit 12 with the optical ON / OFF function is started.

  Note that after the operation by the new active system is started in step S37, the threshold value Th1 in step S32 is replaced with the threshold value Th3, the threshold value Th2 in step S34 is replaced with the threshold value Th4, and the process of FIG. 4 is executed again. Thus, it is possible to detect disconnection during operation by the new active system.

  As described above, according to the first embodiment, when a disconnection occurs in the active optical fiber, the reflected light increases at the end face of the disconnection, so that the change in the reflected light is detected. It becomes possible to detect the disconnection of the optical fiber.

  In the first embodiment, the threshold value Th (Th1 to Th4) is set, and the occurrence of abnormality is detected by comparison with the threshold value Th (Th1 to Th4). For example, as shown in FIG. When the reflected light changes due to the influence, it is possible to prevent the occurrence of disconnection and erroneous detection.

  In the first embodiment, since it is determined that an abnormality has occurred when a state where the intensity of the reflected light exceeds the threshold value Th (Th1 to Th4) continues for a certain time or more, for example, disconnection does not occur. When a physical force is temporarily applied, it is possible to prevent erroneous determination that a disconnection has occurred.

  In the first embodiment, the transmission operation is executed in each of the active system and the standby system before the operation is started, and the intensity of the reflected light at that time is detected and stored, and the threshold values Th1 and Th3 are calculated and stored. Therefore, it is possible to detect an abnormality based on the intensity of normal reflected light before the start of operation.

  In the first embodiment, the intensity of the reflected light of the non-operating system (the standby system in operation in the active system or the active system in operation in the standby system) is detected and stored, and the intensity of the reflected light Threshold values Th2 and Th4 are calculated and stored. As a result, the reflected light of the active system (the active system in operation in the active system or the standby system in operation in the standby system) exceeds the threshold values Th1 and Th3, and the intensity of the reflected light of the non-operating system is the threshold value Th2. When Th4 is exceeded, it can be determined that the disconnection occurs after the coupler 31.

  Although not described in the flowcharts of FIGS. 3 and 4, when switching from the active system to the non-operating system and the intensity of the reflected light of the non-operating system is significantly different from the stored value, It can also be determined that there may be an abnormality in the operational system. For example, when switching from the active system to the standby system, if the intensity of the reflected light of the standby system is significantly different from the stored value, it can be determined that some abnormality has occurred in the standby system.

(B) Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 5, parts corresponding to those in FIG. Compared with FIG. 1, FIG. 5 includes a transmission unit 11 with an optical ON / OFF function, a reflected light detection unit 13, and a coupler 15 integrally configured as a transmission control unit 50, and a transmission unit with an optical ON / OFF function. 12, the reflected light detection unit 14 and the coupler 16 are integrally configured as a transmission control unit 60. Other configurations are the same as those in FIG.

  Here, the E / O 51 converts a broadcast signal, which is an electrical signal, into an optical signal and outputs it. The O / E 52 converts the reflected light into an electric signal and outputs it. The coupler 53 sends an optical signal output from the E / O 51 to the optical fiber 21 and supplies reflected light transmitted through the optical fiber 21 to the O / E 52. On the other hand, the E / O 61 converts the broadcast signal into an optical signal and outputs it. The O / E 62 converts the reflected light into an electrical signal and outputs it. The coupler 63 sends an optical signal output from the E / O 61 to the optical fiber 22 and supplies reflected light transmitted through the optical fiber 22 to the O / E 62.

  In the second embodiment, the configuration of the center apparatus 10 is different from that of the first embodiment shown in FIG. 1, but the operation is the same as that of the first embodiment, and thus the description of the operation is omitted.

  In the second embodiment, the same effect as that of the first embodiment described above can be expected, and the transmission unit 11 with the optical ON / OFF function, the reflected light detection unit 13, and the coupler 15 are integrally configured as the transmission control unit 50. In addition, since the transmission unit 12 with the optical ON / OFF function, the reflected light detection unit 14, and the coupler 16 are integrally configured as the transmission control unit 60, the configuration can be simplified.

(C) Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 6, parts corresponding to those in FIG. Compared with FIG. 1, the reflected light detection units 13 and 14 of the center apparatus 10 in FIG. 6 are replaced with disconnection detection units 70 and 80, and WDM (Wavelength Division Multiplexer) 91 and 92 are added. Further, WDMs 301 and 302 are added to the closure 30, and termination units 303 and 304 are added. Other configurations are the same as those in FIG.

  Here, the disconnection detection unit 70 includes an E / O 71, an O / E 72, and a coupler 73. The E / O 71 converts the electrical signal into an optical signal having a wavelength of λ2 (≈λ1) and outputs the optical signal. The coupler 73 outputs the optical signal output from the E / O 71 to the WDM 91. Further, the coupler 73 supplies the O / E 72 with reflected light having a wavelength of λ2 output from the WDM 91. The O / E 72 converts the reflected light into an electrical signal and outputs the electrical signal to the transmitter 11 with the optical ON / OFF function.

  The disconnection detection unit 80 includes E / O 81, O / E 82, and a coupler 83. The E / O 81 converts the electrical signal into an optical signal having a wavelength of λ2, and outputs the optical signal. The coupler 83 outputs the optical signal output from the E / O 81 to the WDM 92. Further, the coupler 83 supplies the O / E 82 with reflected light having a wavelength of λ2 output from the WDM 92. The O / E 82 converts the reflected light into an electrical signal and outputs it to the transmitter 12 with the optical ON / OFF function.

  The WDM 91 multiplexes the optical signal having the wavelength λ1 output from the transmission unit 11 with the optical ON / OFF function and the optical signal having the wavelength λ2 output from the disconnection detection unit 70, and outputs the combined optical signal to the optical fiber 21. In addition, among the optical signals having a wavelength of λ2 output from the disconnection detection unit 70, the reflected light reflected by the optical fiber 21 is demultiplexed and supplied to the disconnection detection unit 70. The WDM 92 multiplexes the optical signal having the wavelength λ1 output from the transmission unit 12 with the optical ON / OFF function and the optical signal having the wavelength λ2 output from the disconnection detection unit 80 and outputs the combined optical signal to the optical fiber 22. In addition, among the optical signals having a wavelength of λ2 output from the disconnection detection unit 80, the reflected light reflected by the optical fiber 22 is demultiplexed and supplied to the disconnection detection unit 80.

  The WDM 301 demultiplexes an optical signal having a wavelength of λ 1 transmitted through the optical fiber 21 and supplies the demultiplexed optical signal to the coupler 31, and demultiplexes an optical signal having a wavelength of λ 2 and supplies the demultiplexed optical signal to the termination unit 303. The termination unit 303 terminates an optical signal having a wavelength of λ2 supplied from the WDM 301. As a result, the optical signal having a wavelength of λ2 is converted into heat at the terminal portion 303 that causes reflection. The WDM 302 demultiplexes an optical signal having a wavelength of λ 1 transmitted through the optical fiber 22 and supplies the demultiplexed optical signal to the coupler 31, and demultiplexes an optical signal having a wavelength of λ 2 and supplies the demultiplexed optical signal to the termination unit 304. The termination unit 304 terminates an optical signal with a wavelength of λ2 supplied from the WDM 302. As a result, the optical signal having a wavelength of λ2 is converted into heat at the terminal portion 304 that causes reflection. The coupler 31 distributes the optical signal having the wavelength λ1 supplied from the WDMs 301 and 302 and supplies the optical signal to the optical terminal devices 40-1 to 40-n.

  Next, the operation of the third embodiment will be described. In the third embodiment, for example, if the transmitter 11 with the optical ON / OFF function is set to the active system, the transmitter 11 with the optical ON / OFF function converts the broadcast signal into an optical signal having a wavelength of λ1. Output. The WDM 91 sends an optical signal having a wavelength of λ1 to the optical fiber 21. The optical signal having the wavelength λ 1 transmitted through the optical fiber 21 is incident on the WDM 301, demultiplexed, and output to the coupler 31. The coupler 31 distributes an optical signal having a wavelength of λ1 and outputs the optical signal to the optical terminal devices 40-1 to 40-n.

  When the transmission unit 11 with the optical ON / OFF function is set to the active system, the E / O 71 of the disconnection detection unit 70 outputs an optical signal having a wavelength of λ2 to the coupler 73. The coupler 73 outputs an optical signal having a wavelength of λ2 output from the E / O 71 to the WDM 91. The WDM 91 outputs an optical signal having a wavelength of λ2 to the optical fiber 21. When the optical fiber 21 is normal, the optical signal having a wavelength of λ2 transmitted through the optical fiber 21 is demultiplexed by the WDM 301 and supplied to the termination unit 303. The termination unit 303 terminates an optical signal having a wavelength of λ2. As a result, when the optical fiber 21 is normal, almost no reflected light of the optical signal having the wavelength λ2 is generated.

  On the other hand, when the optical fiber 21 is disconnected, an optical signal having a wavelength of λ2 transmitted through the optical fiber 21 is reflected at the disconnected end face, and thus reflected light is generated. The reflected light is transmitted through the optical fiber 21, is demultiplexed by the WDM 91, and enters the disconnection detection unit 70. The coupler 73 of the disconnection detector 70 supplies the reflected light to the O / E 72. The O / E 72 converts the reflected light into an electrical signal and supplies it to the transmitter 11 with the optical ON / OFF function. As in the case of the first embodiment described above, the transmission unit 11 with the optical ON / OFF function determines that a disconnection has occurred when a state where the intensity of the reflected light exceeds the threshold Th continues for a certain period of time, Execute the switching operation between the primary system and the standby system.

  When switching from the active system to the standby system occurs, the disconnection of the standby system that has newly become the active system can be detected by performing the same operation as that described above. .

  As described above, according to the third embodiment, the same effect as that of the first embodiment described above can be expected, and in the third embodiment, disconnection detection for transmitting an optical signal having a wavelength of λ2. Since the portions 70 and 80 are provided and the WDMs 91 and 92 are provided, the loss of reflected light can be reduced as compared with the case where the couplers 15 and 16 are used. For this reason, the disconnection detection sensitivity can be increased.

(D) Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIG. In FIG. 7, parts corresponding to those in FIG. In FIG. 7, compared with FIG. 1, the transmission units 11 and 12 with the optical ON / OFF function of the center apparatus 10 are excluded, and the optical transmission unit 100 and the optical switching control unit 150 are added. Other configurations are the same as those in FIG.

  The optical transmission unit 100 converts the broadcast signal into an optical signal and outputs the optical signal to the optical switching control unit 150. The optical switching control unit 150 includes an optical switching unit 151, switches the optical switching unit 151 based on the intensity of the reflected light detected by the reflected light detection units 13 and 14, and outputs an optical signal to the coupler 15 or the coupler 16. To do. The optical switching unit 151 includes, for example, an optical switch, and outputs an optical signal supplied from the optical transmission unit 100 to one of the coupler 15 and the coupler 16.

  Next, the operation of the fourth embodiment will be described. For example, when the optical fiber 21 is set to the working system, the optical switching control unit 150 switches the connection of the optical switching unit 151 to the coupler 15 side. As a result, the optical signal output from the optical transmission unit 100 is output to the coupler 15 by the optical switching unit 151. The coupler 15 outputs an optical signal to the optical fiber 21. When the optical fiber 21 is normal, the optical signal is distributed by the coupler 31 and supplied to the optical terminal devices 40-1 to 40-n. On the other hand, when the optical fiber 21 is disconnected, the reflected light reflected by the end face of the disconnection enters the reflected light detection unit 13 via the coupler 15. The reflected light detection unit 13 converts the reflected light into an electrical signal and supplies it to the light switching control unit 150. When the state where the intensity of the reflected light exceeds the threshold value Th continues for a certain time, the light switching control unit 150 determines that a disconnection has occurred, and connects the light switching unit 151 from the coupler 15 side to the coupler 16 side. Switch to. Thereby, the disconnection of the optical fiber 21 can be detected and switched to the optical fiber 22.

  As described above, according to the fourth embodiment, the same effect as that of the first embodiment described above can be expected, and in the fourth embodiment, by using the common optical transmission unit 100, The system configuration can be simplified.

(E) Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIG. In FIG. 8, the same reference numerals are given to the portions corresponding to those in FIG. In FIG. 8, compared to FIG. 7, the light switching control unit 150, the reflected light detection units 13 and 14, and the couplers 15 and 16 are integrally configured as a reflected light detection light switching control unit 160. The other configuration is the same as that of FIG.

  Here, the O / E 161 converts the reflected light supplied from the coupler 15 into an electric signal and outputs it. The O / E 162 converts the reflected light supplied from the coupler 16 into an electrical signal and outputs it. The reflected light detection light switching control unit 160 compares the reflected light detected by the O / E 161 and 162 with the threshold Th, and when it is determined that a disconnection has occurred, the reflected light detection light switching control unit 160 switches the light switching unit 151 to Switch between system and standby system.

  The fifth embodiment is the same as the fourth embodiment except that the light switching control unit 150, the reflected light detection units 13 and 14, and the couplers 15 and 16 are integrally formed as a reflected light detection light switching control unit 160. Since the operation is the same as that of the embodiment and the operation is the same as that of the fourth embodiment, the operation of the fifth embodiment is omitted.

  As described above, according to the fifth embodiment, the same effect as that of the first embodiment described above can be expected, and the fifth embodiment is configured integrally as compared with the fourth embodiment. Further, by using the reflected light detection light switching control unit 160, the configuration of the system can be simplified.

(F) Description of Modified Embodiment Each of the above embodiments is an example, and it is needless to say that the present invention is not limited to the case described above. For example, in each of the above embodiments, the intensity of the reflected light is detected. However, for example, the amount of the reflected light may be detected. In the first, second, fourth, and fifth embodiments, the couplers 15 and 16 are used. However, instead of the couplers 15 and 16, a circulator may be used.

  In the third embodiment, the optical signal having the wavelength λ2 is transmitted only to the optical fiber set as the active system. However, the optical signal having the wavelength λ2 is also transmitted to the optical fiber set as the standby system. Then, by referring to the light intensity of the reflected light, the disconnection of the standby system can be detected.

  In the third embodiment, the WDMs 301 and 302 and the termination units 303 and 304 are provided. However, when the optical signal having the wavelength λ2 does not affect the optical terminal devices 40-1 to 40-n, the WDM 301 is provided. 302 and terminal portions 303 and 304, the optical fibers 21 and 22 may be directly connected to the couplers 31 and 32, respectively.

  In each of the above embodiments, one active system and one standby system are used. However, the present invention can be applied even when there are a plurality of active systems and standby systems.

  In each of the above embodiments, the active and standby optical fibers are automatically selected. For example, a presentation unit for presenting the presence / absence of a disconnection is provided, and the information presented to the presentation unit is provided. Based on the above, the operator may switch between the active and standby optical fibers by operating the operation unit.

  In each of the above embodiments, signals (for example, burst signals) transmitted by the optical terminal devices 40-1 to 40-n are not considered, but for example, the reflected light detection units 13 and 14 can be turned on. By providing a selection means for selecting only the reflected light of the optical signal transmitted from the transmission units 11 and 12 with / OFF function, the influence of the burst signal transmitted by the optical terminal devices 40-1 to 40-n is reduced, The occurrence of false detection can be prevented.

  Further, in the flowcharts shown in FIGS. 3 and 4, the intensity of the reflected light of the active system and the standby system is detected before the start of operation. For example, the intensity of the reflected light of the active system is detected after the operation of the active system is started. When it is detected and switched from the active system to the standby system, the intensity of the reflected light of the standby system may be detected after the operation of the standby system is started.

10 Center device 11, 12 Transmitter with optical ON / OFF function (transmitting means, detecting means, switching means)
13, 14 Reflected light detection unit (reception means, standby system reception means)
15, 16 coupler 20 optical transmission line 21, 22 optical fiber 30 closure 31 coupler (mixing means, distribution means)
40 optical terminal device group 40-1 to 40-n optical terminal device 50, 60 transmission control unit (detection means, switching means)
51, 61 E / O (transmission means)
52, 62 O / E (receiving means, receiving means for standby system)
70, 80 Disconnection detector 71, 81 E / O (transmission means)
72, 82 O / E (receiving means, receiving means for standby system)
91, 92, 301, 302 WDM
100 Optical transmitter (transmission means)
150 Optical switching control unit (detection means)
151 Light switching part (switching means)
160 Reflected light detection light switching control unit (detection means, switching means)
161, 162 O / E (receiving means, receiving means for standby system)
304,305 Termination

Claims (8)

In a broadcasting system that transmits a broadcast signal by light from a center device to a plurality of optical terminal devices via a redundant optical fiber,
The center device is
A transmission means for transmitting an optical signal to the optical fiber of the working system;
Receiving means for receiving reflected light that is reflected and returned from the working optical fiber out of the optical signals transmitted from the transmitting means;
Detecting means for detecting occurrence of a failure in the working optical fiber from a change in intensity of reflected light received by the receiving means;
When the occurrence of a failure is detected in the working optical fiber by the detecting means, the switching means for switching to the standby optical fiber,
When the state where the intensity of the reflected light exceeds a predetermined threshold continues for a predetermined time, the detection means detects the occurrence of a failure in the active optical fiber, and the intensity of the reflected light exceeds the predetermined threshold. If it does not continue for a predetermined time even if exceeded, it will not be detected as a failure in the working optical fiber ,
The broadcast system according to claim 1, wherein the predetermined time is several seconds or more .   The broadcasting system according to claim 1, wherein the predetermined time is several seconds.   The broadcasting system according to claim 1, wherein the transmission unit transmits the broadcast signal as the optical signal to the working optical fiber.   The broadcast system according to claim 1, wherein the transmission unit transmits an optical signal having a wavelength different from that of the broadcast signal to the working optical fiber. Mixing means for mixing the light transmitted through the active and standby optical fibers;
Distributing means for distributing the light mixed by the mixing means and supplying the light to the plurality of optical terminal devices;
Standby system receiving means for receiving the reflected light of the standby optical fiber,
The detection means determines that a failure has occurred in an optical fiber subsequent to the distribution means when the light intensity of the reflected light received by the standby reception means has changed,
The broadcast system according to any one of claims 1 to 4, wherein In the center device of the broadcasting system for transmitting a broadcast signal by light from the center device to a plurality of optical terminal devices via the redundant optical fiber,
A transmission means for transmitting an optical signal to the optical fiber of the working system;
Receiving means for receiving reflected light that is reflected and returned from the working optical fiber out of the optical signals transmitted from the transmitting means;
Detecting means for detecting occurrence of a failure in the working optical fiber from a change in intensity of reflected light received by the receiving means;
When the occurrence of a failure is detected in the working optical fiber by the detecting means, the switching means for switching to the standby optical fiber,
When the state where the intensity of the reflected light exceeds a predetermined threshold continues for a predetermined time, the detection means detects the occurrence of a failure in the active optical fiber, and the intensity of the reflected light exceeds the predetermined threshold. If it does not continue for a predetermined time even if exceeded, it will not be detected as a failure in the working optical fiber ,
The center apparatus characterized in that the predetermined time is several seconds or more . In a broadcasting system that transmits a broadcast signal by light from a center device to a plurality of optical terminal devices via a redundant optical fiber,
Mixing means for mixing the light transmitted through the active and standby optical fibers;
Distributing means for distributing the light mixed by the mixing means and supplying the light to the plurality of optical terminal devices, and
The center device is
Transmitting means for transmitting an optical signal to the optical fiber of the working system;
Receiving means for receiving reflected light that is reflected and returned from the working optical fiber out of the optical signals transmitted from the transmitting means;
Detecting means for detecting occurrence of a failure in the working optical fiber from a change in intensity of reflected light received by the receiving means;
Standby system receiving means for receiving the reflected light of the standby optical fiber,
The detection means determines that a failure has occurred in an optical fiber subsequent to the distribution means when the light intensity of the reflected light received by the standby reception means has changed,
A broadcasting system characterized by that. A broadcasting system for transmitting a broadcast signal by light from a center device to a plurality of optical terminal devices via a redundant optical fiber, and mixing means for mixing light transmitted through an active optical fiber and a standby optical fiber; A distribution unit that distributes the light mixed by the mixing unit and supplies the mixed light to the plurality of optical terminal devices.
Transmitting means for transmitting an optical signal to the optical fiber of the working system;
Receiving means for receiving reflected light that is reflected and returned from the working optical fiber out of the optical signals transmitted from the transmitting means;
Detecting means for detecting occurrence of a failure in the working optical fiber from a change in intensity of reflected light received by the receiving means;
Standby system receiving means for receiving the reflected light of the standby optical fiber,
The detection means determines that a failure has occurred in an optical fiber subsequent to the distribution means when the light intensity of the reflected light received by the standby reception means has changed,
A center device characterized by that.

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