JP5871441B2 - Broadcast system and optical terminal device - Google Patents

Description

  The present invention relates to a broadcasting system and an optical terminal device.

  FIG. 8 shows a typical system configuration of a broadcast service using a 1-to-N type 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 demultiplexed, it is sent to the optical transmission line 2. The light transmitted to the optical transmission line 2 is demultiplexed by the optical couplers 2b-1 to 2b-m arranged in the closure after passing through the higher-order optical transmission line 2a, and is arranged in the subscriber's home. The devices 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. 9 shows two optical transmitters 1a-1 and 1a-2 and optical amplifiers 1b-1 and 1b-2, respectively, and a distributor 1d for distributing light into two parts. A configuration is shown in which redundancy is achieved by selecting one of the two systems. According to such a configuration, even if one of the two systems breaks down, 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 demultiplexed by the optical coupler 124 into the optical receiver 131 and the optical coupler 125. 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 device 110, as shown in FIG. 11, the return light is converted into electrical 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 electrical 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 provides a broadcasting system and an optical terminal device capable of more reliably detecting an optical fiber abnormality without incurring an increase in cost. It is aimed.

In order to solve the above problems, the present invention provides a broadcasting system in which a broadcast signal is transmitted from a center device to a plurality of optical terminal devices via light via a redundant transmission path, and at least one of the optical terminal devices is And transmitting means for transmitting upstream light having a wavelength different from that of light transmitted from the center apparatus to the center apparatus, and at least one optical terminal apparatus having the transmitting means is disposed for each predetermined area. The center device is provided for each of the redundant transmission paths, and extracts means for extracting the upstream light transmitted from the transmission means for each transmission path;
Based on the state of the upstream light extracted by the extraction means, a selection means for selecting a transmission path for transmitting the broadcast signal from the redundant transmission paths, and the uplink extracted by the extraction means Separating means for separating light for each optical terminal apparatus, and estimating means for estimating a reception state for each optical terminal apparatus based on the state of the upstream light separated by the separating means. Features.
According to such a configuration, it is possible to more reliably detect an optical fiber abnormality without causing an increase in cost and to select a transmission path with a simple configuration.

In addition, according to one aspect of the present invention, a transmission path having a good state is specified based on the state of the upstream light for each transmission path extracted by the extraction means, and the specified transmission path is selected by the selection means. It has the control means which performs control to perform.
According to such a configuration, it is possible to automatically select a transmission path having a relatively good state.

Further, one aspect of the present invention includes a presentation unit that presents the state of the upstream light for each transmission path extracted by the extraction unit, and the state is good based on information presented to the presentation unit. The transmission path is specified by an operator, and the transmission path specified by the operator operating the selection means is selected.
According to such a configuration, the transmission path can be selected while confirming the information presented by the operator, so that the transmission path can be selected.

In one aspect of the present invention, the transmitting unit uses upstream light having a different wavelength for each optical terminal device, and the separating unit separates upstream light for each optical terminal device according to the wavelength. It is characterized by.
According to such a configuration, it becomes possible to separate upstream light for each optical terminal device.

One aspect of the present invention is characterized in that the extraction means is an optical coupler or a WDM module.
According to such a configuration, it becomes possible to extract upstream light.

  According to the present invention, it is possible to provide a broadcasting system and an optical terminal device capable of more reliably detecting an abnormality in an optical fiber while suppressing an increase in cost as compared with the conventional art.

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 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 optical terminal device with a monitoring function shown in FIG. 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 structural example of the power supply device which concerns on 6th 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, a higher-order optical transmission line 20, a closure 30, optical terminal devices 40-1 to 40-n, and a light emitting unit. 50.

  Here, the light switching unit 11 is a means for switching light, and is constituted by, for example, an optical switch. The optical switching unit 11 is controlled by the control unit 12 and sends the input broadcast signal having a wavelength of λ1 to either the optical coupler 15 or the optical coupler 16. The control unit 12 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an I / F (Interface), and the like, and is based on a program stored in the ROM. Control each part of the device.

  The light receiving units 13 and 14 are configured by, for example, photodiodes, and convert the optical signals output from the optical couplers 15 and 16 into electrical signals and output the electrical signals to the control unit 12. The optical coupler 15 outputs the light incident from the optical switching unit 11 to the route A of the higher-order optical transmission path 20, demultiplexes the light incident from the route A, and enters the light receiving unit 13. . The optical coupler 16 outputs the light incident from the optical switching unit 11 to the route B of the higher-order optical transmission path 20, demultiplexes the light incident from the route B, and enters the light receiving unit 14. .

  The higher-order optical transmission path 20 has two redundant optical transmission paths, Route A and Route B. The optical coupler 31 and the optical coupler 32 configure a closure, for example. The optical coupler 31 combines the lights transmitted from the center apparatus 10 via the route A or the route B and outputs the combined light to the optical coupler 32. Further, the light output from the light emitting unit 50 and emitted through the optical coupler 32 is incident, demultiplexed into the route A and the route B, and output. The optical coupler 32 receives the light emitted from the optical coupler 31 and outputs the light to the optical terminal devices 40-1 to 40-n and the light emitting unit 50. The optical coupler 32 receives the light output from the light emitting unit 50 and receives the light. 31 is emitted. The light emitting unit 50 may be connected to the optical coupler 31.

  The optical terminal devices 40-1 to 40-n are configured by, for example, V-ONUs (Video Optical Network Units) installed in the subscriber's homes, and receive optical signals transmitted from the center device 10 to receive electricity. Convert to signal and output as broadcast signal. The light emitting unit 50 includes a semiconductor laser and a power supply unit, generates an optical signal having a wavelength of λ2 (hereinafter referred to as “upstream light”), and supplies the optical signal to the optical coupler 32. The optical signal transmitted by the center apparatus 10 has a wavelength λ1, which is different from the wavelength λ2 of the optical signal generated by the light emitting unit 50. For this reason, even if upstream light is transmitted to the same optical fiber as the optical signal from the center apparatus 10, the optical signal is not deteriorated by interference. As an example, the wavelength λ1 of the light transmitted by the center apparatus 10 can be set to 1550 nm to 1560 nm, and the upstream light can be set to 1460 to 1540 nm or 1560 to 1620 nm as an example. Of course, other settings may be used as long as the wavelengths are not the same. Note that the light emitting unit 50 may be incorporated in the optical terminal devices 40-1 to 40-n (or other optical terminal devices), or a plurality of light emitting units 50 may be provided in preparation for failure. Good.

  Next, the operation of the first embodiment of the present invention will be described. For example, the light emitting unit 50 always generates and outputs upstream light having a wavelength of λ2. Instead of always emitting light, for example, the operator may operate to emit light or periodically emit light. Further, the light emitting unit 50 is not always connected to the optical coupler 32, but may be connected to the optical coupler 32 as necessary, for example.

  The upstream light incident on the optical coupler 32 is emitted to the optical coupler 31. The optical coupler 31 demultiplexes the upstream light and emits it to the route A and the route B. Note that when the demultiplexing ratio of the optical coupler 31 is 1: 1, the intensity of the upstream light output to the route A and the route B is about 1: 1. Depending on the transmission loss of route A and route B, a demultiplexing ratio other than one-to-one may be selected. In this case, the intensity of upstream light is an intensity corresponding to the demultiplexing ratio.

  The upstream light output from the optical coupler 31 enters the optical coupler 15 and the optical coupler 16 via the route A and the route B, respectively. The optical coupler 15 demultiplexes the incident upstream light and outputs it to the light receiving unit 13. Similarly, the optical coupler 16 demultiplexes the incident upstream light and outputs it to the light receiving unit 14.

  The light receiving unit 13 converts the upstream light output from the optical coupler 15 into a corresponding electrical signal and outputs it to the control unit 12. Similarly, the light receiving unit 14 converts the upstream light output from the optical coupler 16 into a corresponding electrical signal and outputs it to the control unit 12.

  The control unit 12 receives the signals supplied from the light receiving unit 13 and the light receiving unit 14, compares the signal level of each route with a reference value for determining the quality of the transmission path, and determines the state (good or bad) of each route. Determine. Then, the control unit 12 controls the optical switching unit 11 and selects a transmission path according to a predetermined priority order among the routes determined to be in good condition. For example, when it is determined that both the routes A and B are in good condition, the route is selected according to a predetermined priority order. For example, if it is determined that only route A is good, route A is selected. Instead of deciding the priority in advance, for example, the active system and the standby system are determined in advance, and if the status of the active system is good, the active system is selected or a good route is arbitrarily selected. Or a transmission path having a relatively good route state (for example, a relatively high signal level) can be selected. That is, (A) a method in which priority is determined in advance and switching based on the priority, (B) a method in which a working system and a standby system are determined and a failure occurs in the working system, and (C) a good route is arbitrarily selected There are a method for switching to (for example, at random) and a method (D) for switching to a good route according to the state of the route. Of course, other methods may be used. As a result of the above processing, for example, when route B is selected, the optical switching unit 11 selects the optical coupler 16, so that an optical signal having a wavelength of λ1 incident on the optical switching unit 11 is transmitted to the optical coupler 16. Via route B. The optical signal sent to the route B is supplied to the optical terminal devices 40-1 to 40-n via the optical coupler 31 and the optical coupler 32. As a result, since the route (transmission route) with higher upstream light intensity is selected, for example, even when a failure occurs in either route A or route B of the higher-order optical transmission line 20, the other Since the optical signal can be transmitted through the route, it is possible to prevent the broadcasting service from being stopped.

  As described above, according to the first embodiment of the present invention, the light emitting unit 50 is connected to the optical coupler 32, and upstream light having a wavelength different from that of the optical signal is generated and output to be redundant. Since the center device 10 receives the signal via the higher-order optical transmission path 20 and selects the received upstream light having the higher intensity as the active system, it is not necessary to separately lay an optical fiber dedicated to upstream. Cost can be reduced.

  Further, since upstream light is transmitted via the same path as downstream optical signals, it is possible to more reliably detect an optical path failure. Furthermore, since the light emitting unit 50 has only a power source and a laser diode, the cost can be reduced by simplifying the configuration of the apparatus.

  In addition, when the light emission part 50 is light-emitting constantly, the control part 12 can perform the above processes regularly. Moreover, when the light emission part 50 light-emits regularly, the control part 12 can perform the above process at the time of detecting upstream light.

(B) Second embodiment

  Next, a second embodiment of the present invention will be described. FIG. 2 is a diagram for explaining a broadcasting system according to the second embodiment of the present invention. In FIG. 2, parts corresponding to those in FIG. In the example of FIG. 2, the optical couplers 15 and 16 are replaced with WDM (Wavelength Division Multiplexing) modules 65 and 66 as compared with FIG. Other configurations are the same as those in FIG. Here, the WDM modules 65 and 66 selectively demultiplex the upstream light having a wavelength of λ 2 from the optical signals incident from the routes A and B, and supply them to the light receiving units 13 and 14.

  In the second embodiment, by using the WDM modules 65 and 66, the upstream light having a wavelength of λ2 out of the light incident from the routes A and B is selectively demultiplexed to the light receiving units 13 and 14. By guiding, most of the upstream light can be guided to the light receiving units 13 and 14. Thereby, when the level of the light which the light emission part 50 outputs is the same as 1st Embodiment, the level of the upstream light which the light-receiving parts 13 and 14 inject can be made high. Further, when the level of the upstream light incident on the light receiving units 13 and 14 is set to be the same as that in the first embodiment, the light output level of the light emitting unit 50 can be set low. In the second embodiment, the same effect as that of the first embodiment described above can be obtained.

(C) Third embodiment

  Next, a broadcasting system according to the third embodiment of the present invention will be described with reference to FIG. 3, parts corresponding to those in FIG. 1 are given the same reference numerals and explanation thereof is omitted. In FIG. 3, as compared with FIG. 1, the light emitting unit 50 is replaced with an optical terminal device 70 with a monitoring function. Other configurations are the same as those in FIG.

  Here, the optical terminal device with a monitoring function 70 has a monitoring function and a function of transmitting upstream light having a wavelength of λ2 in an optical terminal device (having the same configuration as the optical terminal devices 40-1 to 40-n). Composed by adding. 4 is a diagram illustrating a configuration example of the optical terminal device with a monitoring function 70 illustrated in FIG. As shown in FIG. 4, the optical terminal device with a monitoring function 70 includes a light receiving unit 71, a light receiving state monitoring unit 72, a light emitting unit 73, and a power supply unit 74 as main components. Here, the light receiving unit 71 converts the optical signal (wavelength λ <b> 1) transmitted from the center device 10 into an electrical signal and supplies the electrical signal to the light receiving state monitoring unit 72. Based on the electrical signal supplied from the light receiving unit 71, the light receiving state monitoring unit 72 determines the quality of the signal level of the optical signal, determines the quality of the power supply voltage supplied from the power supply unit 74, or is not illustrated. Monitor the status of other parts of the device. The light reception state monitoring unit 72 generates information according to the signal level and reception state of the detected optical signal or the monitoring result of each unit of the apparatus, and controls the light emitting unit 73 to provide information on the monitoring result to the upstream light. Superimpose and send. The power supply unit 74 supplies power to each unit of the apparatus. For example, a reception processing unit is provided, a signal converted into an electric signal by the light receiving unit 71 is input, the quality of the signal state of the optical signal is determined based on the error occurrence rate of the signal, and the determination result is combined. You may make it transmit.

  Next, the operation of the third embodiment will be described. In the third embodiment, the light receiving state monitoring unit 72 detects the level of the electrical signal supplied from the light receiving unit 71, and determines that an abnormality has occurred, for example, when the signal level falls below a predetermined threshold. Otherwise, it is determined to be normal. It should be noted that instead of the absolute value of the level of the electric signal, a temporal variation (for example, a temporal decrease) is monitored, and when the temporal variation exceeds a predetermined threshold, it is determined that there is an abnormality. Good. The light reception state monitoring unit 72 determines whether the power supply unit 74 is in a good or bad state by determining whether the power supply voltage supplied from the power supply unit 74 is within a predetermined voltage range. Furthermore, it is possible to determine whether an abnormal voltage due to lightning or the like is applied besides the power supply unit. As described above, a reception processing unit is provided, and the light reception state monitoring unit 72 determines the quality of the received signal based on the reception state (for example, error occurrence rate, synchronization state, modulation degree, etc.) of the reception processing unit. You may make it do. For example, when the error occurrence rate exceeds a predetermined threshold, it can be determined that there is an abnormality.

  The light reception state monitoring unit 72 monitors the reception state and the device state as described above, and controls the light emitting unit 73 based on the monitoring result to output upstream light. For example, by generating bit data indicating the state of each unit and causing the light emitting unit 73 to emit light based on the bit data, information indicating the monitoring result can be superimposed on the upstream light and transmitted to the center device 10. .

  The upstream light transmitted in this way is sent to routes A and B via optical couplers 32 and 31. The upstream light propagated through the routes A and B enters the light receiving units 13 and 14 via the optical couplers 15 and 16 and is converted into an electric signal. The control unit 12 determines the quality of the transmission path by comparing a reference value set in advance to determine the quality of the transmission path with an electrical signal. Note that the reference value for determining the quality of the transmission path may not be set in advance, but may be determined according to the state of the route at that time. Of course, the reference value may be determined by other methods. The control unit 12 can also detect the state of the optical terminal device with a monitoring function 70 based on information included in the electrical signals supplied from the light receiving units 13 and 14.

  As described above, the control unit 12 can select an optimum transmission path by comparing the intensity of the upstream light transmitted via the routes A and B with a predetermined reference value, and can select the transmission path. If an abnormality occurs, the transmission path can be changed quickly. The reference value may be determined according to the route state as described above. Alternatively, the route may be selected so that the state of the monitoring-function-equipped optical terminal device 70 is good by switching.

  In addition, by receiving information indicating the level of the optical signal that has reached the optical terminal device with a monitoring function 70, it is possible to detect degradation of the transmission path. Furthermore, the same effect as described in the first embodiment can be obtained.

  Although the optical couplers 15 and 16 are used in the configuration shown in FIG. 3, WDM modules 65 and 66 may be used as in FIG. According to such a configuration, upstream light can be efficiently guided to the light receiving units 13 and 14.

(D) Fourth Embodiment Next, a broadcasting system according to a fourth embodiment of the present invention will be described with reference to FIG. In FIG. 5, parts corresponding to those in FIG. In FIG. 5, compared with FIG. 2, the WDM module 65 selectively demultiplexes the optical signals of λ2 and λ3, and enters the light receiving unit 13 and the light receiving unit 83, and the WDM module 66 is λ2 And λ3 optical signals are selectively demultiplexed and incident on the light receiving unit 14 and the light receiving unit 84. In addition, a light emitting unit 50 that generates upstream light having a wavelength of λ2 is provided in the X area, and an optical terminal device with a monitoring function 70 that generates upstream light having a wavelength of λ3 is provided in the Y area. Other configurations are the same as those in FIG.

  Here, similarly to the light receiving units 13 and 14, the light receiving units 83 and 84 are configured by, for example, a photodiode or the like, and convert the upstream light into a corresponding electric signal and output it. As described above, the WDM module 65 receives the upstream light propagating through the route A, demultiplexes the upstream light having the wavelength of λ2 (upstream light from the light emitting unit 50), and supplies the demultiplexed light to the light receiving unit 13. The upstream light of λ3 (upstream light from the optical terminal device with a monitoring function 70) is demultiplexed and supplied to the light receiving unit 83. The WDM module 66 receives upstream light propagating through the route B, demultiplexes upstream light having a wavelength of λ2 (upstream light from the light emitting unit 50), supplies the demultiplexed light to the light receiving unit 14, and upstream light having a wavelength of λ3 ( (Upstream light from the optical terminal device with a monitoring function 70) is demultiplexed and supplied to the light receiving unit 84.

  The light emitting unit 50 includes a semiconductor laser element that generates upstream light having a wavelength λ2 and a power supply unit. In the example of FIG. 5, the light emitting unit 50 is disposed in the X area.

  The optical terminal device with a monitoring function 70 has the same configuration as that of FIG. 4, monitors the reception state and internal state of the received optical signal, superimposes information indicating the monitoring result on the test signal having the wavelength λ3, It transmits to the center apparatus 10. In the example of FIG. 5, the optical terminal device with a monitoring function 70 is arranged in the Y district.

  Next, the operation of the fourth embodiment will be described. The upstream light having a wavelength of λ2 output from the light emitting unit 50 arranged in the X area is transmitted to the route A and the route B through the optical couplers 32 and 31. The upstream light propagated through the route A is selectively demultiplexed by the WDM module 65 and is incident on the light receiving unit 13. On the other hand, the upstream light transmitted through the route B is selectively demultiplexed by the WDM module 66 and is incident on the light receiving unit 14. The control unit 12 compares the signal level supplied from the light receiving units 13 and 14 with a reference value for determining the state of the route, and, for example, based on a predetermined priority order among routes exceeding the reference value. Select one route. Note that it is also possible to select a route by any of the methods described in the first embodiment, not based on a predetermined priority order.

  The monitoring function-equipped optical terminal device 70 arranged in the Y area transmits upstream light (light having a wavelength λ3) in which information indicating the state of the optical signal and the internal state is superimposed. This upstream light is transmitted to route A and route B through optical couplers 32 and 31. The upstream light propagated through the route A is selectively demultiplexed by the WDM module 65 and is incident on the light receiving unit 83. On the other hand, the upstream light propagated through the route B is selectively demultiplexed by the WDM module 66 and is incident on the light receiving unit 84. The control unit 12 compares the signals supplied from the light receiving units 83 and 84 with a reference value, and can select one of the routes exceeding the reference value based on a predetermined priority order. Of course, it is also possible to select a route by any of the methods described in the first embodiment. Further, the control unit 12 can also estimate the failure factor by referring to the outputs of the light receiving units 13 and 14 and the light receiving units 83 and 84. For example, when only the light receiving units 13 and 14 are abnormal, it can be determined that the light emitting unit 50 is abnormal. If only the light receiving units 13 and 83 are abnormal, it can be determined that the route A is abnormal. Moreover, the control part 12 can know the state of the optical terminal device 70 with a monitoring function by extracting the information superimposed on the upstream light. For this reason, by receiving information indicating the level of the optical signal reaching the monitoring function-equipped optical terminal device 70, it is possible to detect the deterioration of the transmission path and the like.

  As described above, in the fourth embodiment, it is possible to determine whether the light emitting unit is abnormal or the route is abnormal by selecting an optimum route and referring to the output signal of the light receiving unit. Thereby, the repair object can be clarified.

(E) Fifth Embodiment Next, a broadcasting system according to a fifth embodiment of the present invention will be described with reference to FIG. In FIG. 6, parts corresponding to those in FIG. In FIG. 6, compared with FIG. 5, the light emitting unit 50 arranged in the X area is replaced with the optical terminal device with monitoring function 70-2, and the optical terminal device with monitoring function is replaced with the optical terminal device with monitoring function. 70-1 is substituted. Other configurations are the same as those in FIG. The monitoring function-equipped optical terminal devices 70-1 and 70-2 have the same configuration as that in FIG.

  In 5th Embodiment, since the optical terminal device with a monitoring function is arrange | positioned for every district, in the center apparatus 10, the level of the optical signal which reaches | attains the optical terminal devices 70-1 and 70-2 with a monitoring function is grasped | ascertained. be able to. In addition, by taking into account information from the optical terminal devices 70-1 and 70-2 with a monitoring function, for example, due to an abnormality in the commercial power supply (for example, an abnormality in voltage, etc.) that occurred in the X area, the monitoring function If an abnormality has occurred in the power supply voltage of the optical terminal device 70-2, this can be detected. For this reason, it can be determined whether the occurrence of the abnormality is caused by the transmission path or the optical terminal devices 70-1, 70-2 with a monitoring function. Note that when a power source such as an electrolytic capacitor or a backup battery is provided and the commercial power source fails, the center device 10 indicates that the commercial power source has a power failure based on the power stored in these power sources. May be notified.

  In FIG. 5, the light emitting unit 50 is disposed in the X area, the optical terminal device 70 with a monitoring function is disposed in the Y area, and the optical terminal device 70-1 with a monitoring function is disposed in both the X area and the Y area in FIG. , 70-2 are arranged, but this is an example, and other arrangements may be used. For example, the light emitting units 50 may be arranged in both the X and Y districts, or the optical terminal device 70 with a monitoring function may be arranged in the X district and the light emitting units 50 may be arranged in the Y district. Moreover, you may make it arrange | position the several light emission part 50 or the optical terminal device 70 with a monitoring function in one area. According to such a configuration, a failure is likely to occur, and there is a time for recovery when the failure occurs. For example, a plurality of light emitting units 50 or an optical terminal device with a monitoring function is provided in a place such as a mountainous area. By arranging 70, it is possible to quickly identify the location where an abnormality has occurred.

(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 control unit 12 is provided, and the state of the route is detected by the control unit 12 and the route is automatically selected. For example, as shown in FIG. 100 may be provided, and the transmission path may be selected by the operator operating the operation unit 101 based on the information presented on the presentation unit 100. More specifically, in the sixth embodiment shown in FIG. 7, compared to FIG. 1, the control unit 12 is excluded and a presentation unit 100 and an operation unit 101 are added. Here, the presenting unit 100 presents the comparison result of the upstream light received by the light receiving units 13 and 14 to the operator. As a presentation method, for example, information indicating a currently used transmission path (active system) and information indicating an optimum path may be presented by, for example, an LED (Light Emitting Diode), or an LCD ( It may be presented on a Liquid Crystal Display) or presented by voice. The operation unit 101 switches the connection of the light switching unit 11 when an operation is performed by the operator. Next, the operation of the sixth embodiment shown in FIG. 7 will be described. The upstream light transmitted from the light emitting unit 50 is incident on the optical couplers 15 and 16 via the routes A and B. The optical couplers 15 and 16 demultiplex the upstream light and enter the light receiving units 13 and 14. The light receiving units 13 and 14 convert the upstream light into an electrical signal and output it. For example, the presentation unit 100 can convert the electrical signal output from the light receiving units 13 and 14 into a digital signal, and display the obtained digital signal on a monitor. Such a digital signal may be recorded as a log in the recording unit. By comparing these values, the operator can specify an optimum route with little attenuation. In addition to this, for example, the electrical signals output from the light receiving units 13 and 14 may be amplified with a predetermined gain to light two LEDs. According to such a configuration, the two LEDs are lit at a brightness corresponding to the attenuation of the test light in the routes A and B. Therefore, by comparing these brightnesses, the operator can optimize the less attenuation. A specific route can be identified. When the route is specified, the operator can select the optimum route by operating the operation unit 101 and switching the light switching unit 11. Instead of operating the operation unit 101, for example, the operator may replace the optical fiber or switch the connection of the fiber distribution board. Further, the presentation unit 100 may compare the electric signals supplied from the light receiving units 13 and 14 and display information indicating the comparison result.

  Further, in each of the embodiments described above, there are two routes A and B, but three or more routes may be provided. Further, in each of the above embodiments, the light emitting unit 50 has been described as an example of continuously emitting light. However, for example, the light emitting unit 50 may emit light intermittently or at regular intervals. Alternatively, an optimal signal may be selected by superimposing an electrical signal having a specific frequency on upstream light and comparing the signal level of the same frequency included in the electrical signal with a reference. Further, instead of emitting light at a constant intensity, modulation may be performed according to predetermined data, and an optimal path may be selected according to an error rate when the modulated data is demodulated. Alternatively, the optimal route may be selected by increasing or decreasing the emission intensity with time and comparing the timing when the output of the light receiving unit exceeds or falls below a predetermined threshold. Alternatively, a synchronization signal may be transmitted, a PLL (Phase Locked Loop) may be configured based on the synchronization signal, and a path locked by the PLL may be selected.

  Further, in each of the embodiments described above, the number of optical terminal devices or light emitting units with a monitoring function arranged in each area is one, but a plurality may be arranged. According to such a configuration, when an abnormality is detected, it is distinguished whether an abnormality has occurred in the entire district, or whether an abnormality has occurred in a specific optical terminal device with a monitoring function or a light emitting unit. be able to.

  Further, in each of the above embodiments, when multiplexing upstream light, multiplexing by wavelength (multiplexing by λ2 and λ3) is performed. However, for example, frequency division multiplexing is performed, or time multiplexing is performed. It is also possible to perform division multiplexing. For example, in the former case, upstream light may be modulated with a different frequency for each area, and the center device 10 may extract a signal with a specific frequency by a filter after photoelectric conversion. In the latter case, multiplexing can be performed by determining the time for each district and transmitting upstream light. In addition to these, for example, multiplexing may be performed by a spread spectrum method using pseudo noise or the like, or modulation by phase change or amplitude change with respect to a reference signal may be performed.

  In each of the embodiments described above, the light emitting unit and the optical terminal device with a monitoring function are connected to the optical coupler 32, but may be connected to the optical coupler 31. Of course, a light emitting unit or an optical terminal device with a monitoring function may be connected to both the optical coupler 31 and the optical coupler 32.

10 Center device 11 Optical switching part (selection means)
12 Control unit (control means, estimation means)
13, 14, 83, 84 Light-receiving part 15, 16 Optical coupler (extraction means)
DESCRIPTION OF SYMBOLS 20 Upper side optical transmission line 30 Closure 31, 32 Optical coupler 40-1 to 40-n Optical terminal device 50 Light emission part (optical terminal device, transmission means)
65, 66 WDM module (extraction means, separation means)
70, 70-1, 70-2 Optical terminal device with monitoring function (optical terminal device)
71 Light-receiving part 72 Light-receiving state monitoring part (detection means)
73 Light Emitting Unit (Transmitter)
74 power supply unit 100 presentation unit (presentation means)
101 Operation unit (selection means)

Claims (5)

In a broadcasting system that transmits a broadcast signal from a center device to a plurality of optical terminal devices via light via a redundant transmission path,
At least one of the optical terminal devices is
Transmission means for transmitting upstream light of a wavelength different from the light transmitted from the center device to the center device;
At least one optical terminal device having the transmitting means is arranged for each predetermined area,
The center device is
An extraction unit that is provided for each of the redundant transmission paths and extracts the upstream light transmitted from the transmission unit for each transmission path;
Selection means for selecting a transmission path for transmitting the broadcast signal from the redundant transmission paths based on the state of the upstream light extracted by the extraction means ;
Separating means for separating the upstream light extracted by the extracting means for each optical terminal device;
Estimating means for estimating a reception state for each of the optical terminal devices based on the state of the upstream light separated by the separating means;
Broadcasting system characterized by having a.   Based on the state of the upstream light for each transmission path extracted by the extraction means, the control means for specifying a transmission path in a good state and executing control for selecting the specified transmission path by the selection means The broadcast system according to claim 1. Presenting means for presenting the state of the upstream light for each transmission path extracted by the extracting means;
The operator specifies a transmission path having a good state based on information presented to the presenting means, and selects the transmission path specified by the operator operating the selection means. The broadcasting system described in 1. The transmission means uses upstream light having a different wavelength for each optical terminal device,
The separation means separates upstream light for each of the optical terminal devices according to the wavelength;
The broadcast system according to claim 1. The broadcasting system according to claim 1, wherein the extraction unit is an optical coupler or a WDM module.

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