JP5959458B2 - Optical transmission system, station apparatus, and subscriber apparatus - Google Patents

Description

  The present invention relates to an optical transmission system, a station apparatus, and a subscriber apparatus.

  In Patent Document 1, each of the n subscriber devices 10 to 20 and the station device 30 is provided with two interface units of an active system and a standby system, which are connected by two systems of optical transmission lines 200 and controlled. The units 13 and 3 always supply information on the working interface to the standby interface, and further receive cells periodically generated from the station device 30 by the two systems of the subscriber device, from the station device to the interfaces 11 and 12. Is disclosed, and a technique for correcting the distance difference of information supplied to the standby system is disclosed. In this technique, when a failure occurs in the working optical transmission line and a switching request is made from the outside, the control units 13 and 3 immediately switch between the working transmission line and the standby transmission line and the interface unit.

JP-A-9-284325

  By the way, in the technique shown in Patent Document 1, since the subscriber device needs to have two types of interfaces, an active system and a standby system, there is a problem that a mounting space is required and a manufacturing cost is high.

  The present invention has been made in view of the above points, and an object thereof is to provide an optical transmission system, a station apparatus, and a subscriber apparatus that can reduce the mounting space and the manufacturing cost. Yes.

In order to solve the above-described problems, the present invention provides an optical transmission system having a station apparatus and a subscriber apparatus, which are connected by at least two first and second optical transmission lines. , Station-side transmission means for transmitting an optical signal to the subscriber unit via the first or second optical transmission line, and an optical signal from the subscriber unit via the first and second optical transmission lines A station-side receiving unit that receives the signal, a determination unit that determines a state of the first and second optical transmission lines based on a state of the optical signal received by the station-side receiving unit, and a determination unit that And switching means for switching to the other optical transmission line when it is determined that the state of the one optical transmission line has deteriorated, and the subscriber unit passes through the first and second optical transmission lines. The subscriber side that transmits the optical signal to the station device Possess a signal means, a multiplexing means for multiplexing the said first and second optical signals of the optical transmission line, and subscriber receiver means for receiving the multiplexed optical signal by the multiplexing means, the The determination means detects whether or not the signal level of the optical signal received by the station side receiving means has dropped below a first threshold, and the signal level has dropped below the first threshold. In this case, it is determined that the state of one optical transmission line has deteriorated, and when the signal level exceeds the first threshold value, the signal quality of the optical signal received by the station-side receiving means is second. It is determined whether the state of one of the optical transmission lines has deteriorated when the signal quality is reduced below the second threshold .
According to such a configuration, the mounting space can be reduced and the manufacturing cost can be reduced.

Further, according to one aspect of the present invention, the station-side receiving means receives first and second optical signals from the subscriber unit via the first and second optical transmission lines and converts them into electrical signals. The determination unit includes a photoelectric conversion unit, a switch that selects an electric signal output from one of the first and second photoelectric conversion units, and a decoding unit that decodes the electric signal output from the switch. Refers to the electrical signals output from the first and second photoelectric conversion units, determines whether the signal level of the optical signal has dropped below the first threshold value, and refers to the state of the decoding unit In this way, it is determined whether or not the signal quality of the optical signal has decreased below the second threshold value .

Further, according to one aspect of the present invention, when the switching unit determines that the state of the one optical transmission line has deteriorated by the determination unit, the switching unit adds the optical signal through the one optical transmission line. The light emission of the light emitting element of the station side transmission means for transmitting to the user device is stopped.
According to such a configuration, it is possible to reduce the influence on the system by stopping the light emission of the light emitting element.

Also, one aspect of the present invention is characterized in that the switching means stops light emission of the light emitting element of one station side transmitting means after starting light emission of the light emitting element of the other station side transmitting means. To do .

In addition, the present invention provides the station apparatus that constitutes an optical transmission system that includes a station apparatus and a subscriber apparatus, and connects between them by at least two first and second optical transmission lines. Station-side transmission means for transmitting an optical signal to the subscriber unit via a second optical transmission line, and a station side for receiving an optical signal from the subscriber unit via the first and second optical transmission lines A receiving unit; a determining unit that determines a state of the first and second optical transmission lines based on a state of the optical signal received by the station side receiving unit; and one optical transmission line by the determining unit If the state is determined to have deteriorated, it possesses a switching means for switching to the other optical transmission line, wherein the determining means, the signal level of the optical signal received by the station side receiving means first Whether it falls below the threshold And when the signal level falls below the first threshold, it is determined that the state of one of the optical transmission lines has deteriorated, and when the signal level exceeds the first threshold, the station It is detected whether or not the signal quality of the optical signal received by the side receiving means has dropped below a second threshold, and one optical transmission line when the signal quality falls below the second threshold It is characterized in that it is determined that the state of has deteriorated .
According to such a configuration, the mounting space can be reduced and the manufacturing cost can be reduced.

  According to the present invention, it is possible to provide an optical transmission system, a station apparatus, and a subscriber apparatus that can reduce the mounting space and reduce the manufacturing cost.

It is a figure which shows the structural example of the optical transmission system which concerns on embodiment of this invention. It is a figure which shows the structural example of the conventional optical transmission system. It is a flowchart for demonstrating an example of the process performed in embodiment of this invention shown in FIG.

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

(A) Description of Configuration of Embodiment FIG. 1 is a diagram illustrating a configuration example of an optical transmission system according to an embodiment of the present invention. As shown in FIG. 1, the optical transmission system 1 according to the embodiment of the present invention includes a station device 10, an optical transmission line 20, and a subscriber device 30.

  Here, the station apparatus 10 includes an encoding unit 11, downstream E / O (Electrical Optical: electrical / optical conversion) 12, 13 with ON / OFF function, control unit 14, upstream O / E 15, 16, SW (Switch ) 17 and a decoding unit 18.

  The encoding unit 11 receives the video signal, performs encoding processing, and then outputs the video signal to the downstream E / Os 12 and 13 with the ON / OFF function. The downlink E / O 12 with the ON / OFF function converts the encoded video signal supplied from the encoding unit 11 into an optical signal, and transmits the optical signal to the subscriber device 30 via the optical fiber 21a. The downlink E / O 13 with the ON / OFF function converts the encoded video signal supplied from the encoding unit 11 into an optical signal, and transmits the optical signal to the subscriber device 30 via the optical fiber 22a. The downstream E / Os 12 and 13 with the ON / OFF function have a function of turning on or off a built-in light emitting element in accordance with the control of the control unit 14.

  The control unit 14 refers to the outputs of the upstream O / Es 15 and 16 and the decoding unit 18 and turns on or off the light emitting elements (not shown) incorporated in the downstream E / Os 12 and 13 with ON / OFF function. While controlling, SW17 is controlled. The upstream O / E 15 receives the optical signal transmitted from the subscriber unit 30 via the optical fiber 21b, converts it into an electrical signal, outputs it to the SW 17, and notifies the control unit 14 of the level of the optical signal. . The upstream O / E 16 receives the optical signal transmitted from the subscriber unit 30 via the optical fiber 22b, converts it into an electrical signal, outputs it to the SW 17, and notifies the control unit 14 of the level of the optical signal. .

  Based on the control of the control unit 14, the SW 17 selects an electrical signal output from either the upstream O / E 15 or the upstream O / E 16 and outputs the electrical signal to the decoding unit 18. The decoding unit 18 decodes the electrical signal supplied from the SW 17 and outputs it as a video signal.

  The optical transmission line 20 includes an optical transmission line 21 and an optical transmission line 22. The optical transmission line 21 includes a downstream optical fiber 21a and an upstream optical fiber 21b. The optical transmission line 22 includes a downstream optical fiber 22a and an upstream optical fiber 22b.

  On the other hand, the subscriber unit 30 includes a coupler 31, a downstream O / E 32, a decoding unit 33, a control unit 34, an encoding unit 35, an upstream E / O 36, and a coupler 37.

  Here, the coupler 31 is transmitted from the downstream E / O 12 with the ON / OFF function and transmitted through the optical fiber 21a, and transmitted from the downstream E / O 13 with the ON / OFF function. The optical signal transmitted via 22a is multiplexed and output to the downstream O / E 32.

  The downstream O / E 32 converts the optical signal supplied from the coupler 31 into an electrical signal and outputs the electrical signal to the decoding unit 33. The decoding unit 33 decodes the electrical signal output from the downstream O / E 32 into a video signal and outputs the video signal. The control unit 34 controls the decoding unit 33 and the encoding unit 35. The encoding unit 35 encodes the signal supplied from the control unit 34 and supplies the encoded signal to the upstream E / O 36. The upstream E / O 36 converts the signal supplied from the encoding unit 35 into an optical signal and supplies the optical signal to the coupler 37. The coupler 37 divides the optical signal supplied from the upstream E / O 36 into two, and transmits the optical signal to the station apparatus 10 via the optical fibers 21b and 22b.

(B) Description of Operation of Embodiment Next, the operation of the embodiment of the present invention will be described. Hereinafter, the operation of the conventional configuration example will be described with reference to FIG. 2, and then the operation of the embodiment of the present invention will be described. FIG. 2 is a diagram showing a conventional configuration example. In FIG. 2, parts corresponding to those in FIG. 2, compared with FIG. 1, in the station device 10, the downlink E / Os 12 and 13 with the ON / OFF function are replaced with downlink E / Os 121 and 131. Further, in the subscriber unit 30, the coupler 31 is excluded, the downstream O / E 32 is replaced with the downstream O / E 321, 322, and the SW 323 is added. Other configurations are the same as those in FIG.

  In the example shown in FIG. 2, the electrical signal supplied from the encoding unit 11 is supplied to the downstream E / O 121 and 131, and the downstream E / O 121 and 131 converts the electrical signal supplied from the encoding unit 11 into an optical signal. The data is converted and transmitted to the subscriber unit 30 via the optical fibers 21a and 22a. In the subscriber unit 30, the downstream O / Es 321 and 322 receive the optical signals transmitted through the optical fibers 21a and 22a, convert them into electrical signals, and output them. The SW 323 selects and outputs one of the electrical signals output from the downstream O / Es 321 and 322 according to the control of the control unit 34. Note that the control unit 34 refers to the output of the downstream O / Es 321 and 322, and switches the selection by controlling the SW 323 when the signal level falls below a predetermined threshold. For example, when the optical transmission line 21 is the active system and the optical transmission line 22 is the standby system, the control unit 34 is configured when the signal level of the optical transmission line 21 that is the active system falls below a predetermined threshold. In this case, the switch from the active system to the standby system is executed by controlling the SW 323.

  The electrical signal output from the encoding unit 35 is converted into an optical signal by the upstream E / O 36 and supplied to the coupler 37. The coupler 37 demultiplexes the optical signal into two and transmits it to the station apparatus 10 via the optical fibers 21b and 22b. The station apparatus 10 receives optical signals transmitted through the optical fibers 21b and 22b, converts them into electrical signals in the upstream O / Es 15 and 16, and outputs them to the SW 17. The SW 17 selects one of the electrical signals output from the upstream O / Es 15 and 16 under the control of the control unit 14 and outputs the selected electrical signal to the decoding unit 18. The decoding unit 18 decodes and outputs the signal output from the SW 17. The control unit 14 refers to the level of the output signal of the upstream O / Es 15 and 16 and executes a process of switching to the other by the SW 17 when one of the signal levels decreases. For example, when the optical transmission line 21 is the active system and the optical transmission line 22 is the standby system, the control unit 14 is configured when the signal level of the optical transmission line 21 that is the active system falls below a predetermined threshold. In this case, the switch from the active system to the standby system is executed by controlling the SW 17.

  In the conventional configuration as described above, the subscriber device 30 needs to have the downlink O / Es 321 and 322, and the subscriber device 30 needs to determine the state of the optical transmission line. There is a problem that the mounting space becomes large and the manufacturing cost is high.

  Next, the operation of the embodiment of the present invention will be described with reference to FIG. In the embodiment shown in FIG. 1, the control unit 34 causes the encoding unit 35 to output a predetermined signal (for example, a signal including predetermined data). The electrical signal output from the encoding unit 35 is converted into an optical signal by the upstream E / O 36 and supplied to the coupler 37. The coupler 37 demultiplexes the optical signal supplied from the upstream E / O 36 and transmits it to the station apparatus 10 via the optical fibers 21b and 22b.

  In the station apparatus 10, the optical signals received via the optical fibers 21b and 22b are received by the upstream O / Es 15 and 16, converted into electrical signals, and output to the SW17. The SW 17 selects one of the electrical signals output from the upstream O / Es 15 and 16 according to the control of the control unit 14 and supplies the selected electrical signal to the decoding unit 18. The control unit 14 monitors the signal level and error rate of the electrical signals output from the upstream O / Es 15 and 16, and based on the signal level and error rate, the downstream E / O 12 with ON / OFF function, 13 is controlled. For example, when the optical transmission line 21 is the active system and the optical transmission line 22 is the standby system, the control unit 14 selects the downlink E / O 12 with the ON / OFF function during normal operation. As a result, the downstream E / O 12 with ON / OFF function is turned on in a light emitting element such as a built-in LD (Laser Diode), and the electric signal supplied from the encoding unit 11 is turned on / off. It is converted into an optical signal by the downstream E / O 12 and supplied to the subscriber device 32 via the optical transmission line 21.

  In such a state, when a failure occurs in the optical transmission line 21 (for example, in the case of disconnection), a failure also occurs in the optical fiber 21b. Therefore, the level of the optical signal received by the upstream O / E 15 Or signal quality deteriorates. As a result, the signal level of the electrical signal output from the upstream O / E 15 is reduced (or signal quality is reduced), so that the control unit 14 has the electrical signal below a predetermined threshold (or signal quality). Therefore, it is determined that some failure has occurred in the active optical transmission line 21, and switching from the active system to the standby system is executed. That is, the light emission of the down E / O 12 with the ON / OFF function is stopped and the light emission of the down E / O 13 with the ON / OFF function is started.

  With the above operation, the station device 10 receives the optical signal transmitted from the subscriber device 30, and when the signal level of the optical signal falls below a predetermined intensity (or the signal quality is equal to or lower than a predetermined threshold value). In this case, the emission of the light emitting element of the downstream E / O 12 with the ON / OFF function is stopped and the light emission of the light emitting element of the downstream E / O 13 with the ON / OFF function is started. Thereby, switching from the active system to the standby system is executed.

  As described above, according to the embodiment of the present invention, as shown in the conventional example of FIG. 2, the subscriber device 30 does not need to include the downstream O / Es 321 and 322. This simplifies and reduces the mounting space. Thereby, the manufacturing cost can be reduced.

  In the embodiment shown in FIG. 1, as shown in FIG. 2, the subscriber device 30 does not need to monitor the signal level of the received signal and switch the SW 323 according to the signal level. In addition to simplification, manufacturing costs can be reduced.

  Next, details of processing executed in the embodiment shown in FIG. 1 will be described with reference to FIG. When the processing of the flowchart shown in FIG. 3 is started, the following steps are executed.

  In step S10, the control unit 14 detects the signal level L of the active system. More specifically, the control unit 14 detects the signal level L of the electrical signal output from the upstream O / E 15.

  In step S11, the control unit 14 determines whether or not the signal level L detected in step S10 is equal to or less than a predetermined threshold value Thl, and determines that the signal level L is equal to or less than the predetermined threshold value Thl (step S11: Yes). Proceeds to step S14, otherwise proceeds to step S12 (step S11: No). For example, when the working system is disconnected and the signal level L is equal to or lower than the predetermined threshold value Th1, it is determined Yes in step S11, and the process proceeds to step S14. On the other hand, when the working system is normal, the signal level L is higher than the predetermined threshold value Thl. Therefore, in step S11, No is determined and the process proceeds to step S12.

  In step S12, the control unit 14 detects the signal quality Q of the working signal. For example, the control unit 14 detects a C / N (Carrier Noise) ratio of the working signal. An index other than the C / N ratio (for example, a noise rate) may be detected as the signal quality Q.

  In step S13, the control unit 14 determines whether or not the signal quality Q of the active signal is equal to or lower than a predetermined threshold Thq. If the signal quality Q is equal to or lower than the predetermined threshold Thq (step S12: Yes), the step 14 The process proceeds to S14, and otherwise (step S12: No), the process proceeds to step S17. For example, if the signal quality Q decreases due to the failure of the working optical transmission line 21 and falls below the predetermined threshold Thq, the process proceeds to step S14. If the working optical transmission line 21 is normal, the process proceeds to step 17 because the signal quality Q is greater than the predetermined threshold Thq.

  In step S14, the control unit 14 issues an alarm (not shown). Thereby, it is possible to notify the administrator that an abnormality has occurred.

  In step S15, the control unit 14 starts the operation of the standby system. More specifically, the control unit 14 causes the built-in light emitting element to start emitting light to the downstream E / O 13 with the ON / OFF function. As a result, the electrical signal supplied from the encoding unit 11 is converted into an optical signal by the downstream E / O 13 with the ON / OFF function, and transmitted to the subscriber unit 30 via the standby optical transmission line 22.

  In step S16, the control unit 14 stops the operation of the active system. More specifically, the control unit 14 stops the light emission of the built-in light emitting element with respect to the downstream E / O 12 with the ON / OFF function. Thereby, the output of the optical signal from the downstream E / O 12 with the ON / OFF function is stopped.

  In step S17, the control unit 14 determines whether or not to end the process, and when it is determined that the process is to be continued (step S17: No), the control unit 14 returns to step S10 and continues the same process as described above. In other cases (step S17: Yes), the process is terminated.

  According to the above processing, when the signal level of the optical signal transmitted from the subscriber unit 30 is equal to or lower than the predetermined threshold, switching from the active system to the standby system can be executed. Similarly, when the signal quality of the working system signal is equal to or lower than a predetermined threshold, switching from the working system to the standby system can be executed.

  Further, according to the above processing, when switching from the active system to the standby system is performed, an alarm is issued, so that the administrator can be notified that the switching has been performed.

(C) 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, although the case where there is one subscriber device 30 is illustrated and described in the above embodiment, there may be N (N is a natural number of 2 or more) subscriber devices 30. Further, when there are N units, the switching from the active system to the standby system is not determined based on only the optical signal from one subscriber apparatus 30, but based on the optical signals from a plurality of subscriber apparatuses 30. You may make it judge. Alternatively, a function of transmitting an upstream optical signal may be provided in a part of the N units.

  In the above embodiment, each of the optical transmission lines 21 and 22 is configured by two optical fibers, but may be configured by one or three or more optical fibers. When there is one optical fiber, the downstream optical signal and the upstream optical signal are transmitted through the same optical fiber. For example, the downstream optical signal and the upstream optical signal have different wavelengths. By doing so, communication can be performed normally.

  In the embodiment shown in FIG. 1, the signal from the encoding unit 35 is converted into an optical signal and transmitted by the upstream E / O 36. 10 may detect only the intensity of this light. Of course, light of a certain intensity may be transmitted and modulated as necessary.

  Further, in the flowchart shown in FIG. 3, the state of the working system is determined based on the signal level L of the working system and the signal quality Q of the working system signal, but only one of these is used. You may make it perform determination. When the signal quality Q of the working signal is not to be determined, the subscriber device 30 does not need to superimpose the signal on the upstream optical signal.

  In the embodiment shown in FIG. 1, the downlink E / Os 12 and 13 with the ON / OFF function are used. However, E / O without the ON / OFF function may be used.

  Further, instead of modulating the upstream signal light with a predetermined signal, for example, the upstream signal light may be modulated by an output of an oscillator having a constant frequency.

DESCRIPTION OF SYMBOLS 1 Optical transmission system 10 Station apparatus 11 Encoding part 12, 13 Downstream E / O with ON / OFF function (station side transmission means)
14 Control unit (determination means, switching means)
15, 16 Upstream O / E (station side receiving means)
17 SW
18 Decoding unit 20 Optical transmission line 30 Subscriber device 31 Coupler (multiplexing means)
32 Downstream O / E (subscriber side receiving means)
33 Decoding unit 34 Control unit 35 Encoding unit 36 Downstream E / O (subscriber side transmission means)
37 coupler

Claims (5)

In an optical transmission system having a station device and a subscriber device and connecting between them by at least two first and second optical transmission lines,
The station device is
Station-side transmission means for transmitting an optical signal to the subscriber unit via the first or second optical transmission line;
Station-side receiving means for receiving an optical signal from the subscriber unit via the first and second optical transmission lines;
Determining means for determining the state of the first and second optical transmission lines based on the state of the optical signal received by the station-side receiving means;
If the determination means determines that the state of one optical transmission line has deteriorated, it has switching means for switching to the other optical transmission line,
The subscriber unit is
Subscriber-side transmission means for transmitting an optical signal to the station apparatus via the first and second optical transmission lines;
A multiplexing means for multiplexing the optical signals of the first and second optical transmission lines;
Subscriber-side receiving means for receiving the optical signal combined by the combining means;
I have a,
The determination means detects whether or not the signal level of the optical signal received by the station-side receiving means has dropped below a first threshold, and the signal level has fallen below the first threshold Is determined that the state of one of the optical transmission lines has deteriorated, and if the signal level exceeds the first threshold, the signal quality of the optical signal received by the station-side receiving means is the second Detecting whether or not the signal quality has dropped below a threshold value, and determining that the state of one optical transmission line has deteriorated when the signal quality has dropped below the second threshold value;
An optical transmission system characterized by that. The station-side receiving means receives first and second photoelectric conversion units that receive optical signals from the subscriber unit via the first and second optical transmission lines and convert them into electrical signals, and the first and second photoelectric conversion units, A switch that selects an electrical signal output from one of the second photoelectric conversion units; and a decoding unit that decodes the electrical signal output from the switch;
The determination means determines whether the signal level of the optical signal has decreased below the first threshold with reference to the electrical signals output from the first and second photoelectric conversion units, and the state of the decoding unit To determine whether the signal quality of the optical signal has fallen below the second threshold,
The optical transmission system according to claim 1. The switching means is a station-side transmission means for transmitting an optical signal to the subscriber unit via the one optical transmission line when the determination means determines that the state of the one optical transmission line has deteriorated. The optical transmission system according to claim 1 , wherein the light emission of the light emitting element is stopped . 4. The optical transmission according to claim 3 , wherein the switching unit stops light emission of the light emitting element of one station side transmission unit after starting light emission of the light emitting element of the other station side transmission unit. system. In the above-mentioned station apparatus constituting an optical transmission system having a station apparatus and a subscriber apparatus and connecting between them by first and second optical transmission lines,
Station-side transmission means for transmitting an optical signal to the subscriber unit via the first or second optical transmission line;
Station-side receiving means for receiving an optical signal from the subscriber unit via the first and second optical transmission lines;
Determining means for determining the state of the first and second optical transmission lines based on the state of the optical signal received by the station-side receiving means;
If the determination means determines that the state of one optical transmission line has deteriorated, it has switching means for switching to the other optical transmission line,
The determination means detects whether or not the signal level of the optical signal received by the station-side receiving means has dropped below a first threshold, and the signal level has fallen below the first threshold Is determined that the state of one of the optical transmission lines has deteriorated, and if the signal level exceeds the first threshold, the signal quality of the optical signal received by the station-side receiving means is the second Detecting whether or not the signal quality has dropped below a threshold value, and determining that the state of one optical transmission line has deteriorated when the signal quality has dropped below the second threshold value;
The station apparatus characterized by the above-mentioned.

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