JP4351189B2 - Optical transmission line monitoring method, optical transmission line monitoring program, and optical transmission line monitoring apparatus - Google Patents

Description

  The present invention relates to an optical transmission line monitoring method for monitoring the state of an optical transmission line, an optical transmission line monitoring program, and an optical transmission line monitoring apparatus.

  2. Description of the Related Art In recent years, with the spread of the Internet and the like, an optical communication technique using an optical fiber as a transmission path has become the mainstream as a communication technique for providing high-speed and broadband communication services. In this optical communication technology, accurate data transmission from the transmission side to the reception side is realized by constantly monitoring the transmission state of the optical signal.

  In the conventional monitoring system, the input level of the optical signal and the bit error rate of the received data are monitored on the receiving side, and when they exceed a predetermined threshold or the input of the optical signal is cut off. When an alarm is issued. Also, in an optical transmission network for wavelength-multiplexed data transmission, on the transmission side, an optical signal for a monitoring channel having a wavelength different from that of the original optical signal used for wavelength multiplexing is added to the wavelength-multiplexed optical signal to transmit a transmission line. A method is known in which a monitoring channel optical signal is extracted from the optical signals transmitted on the transmission path and monitored on the reception side to monitor a transmission path failure (for example, see Patent Document 1 below). .)

JP 2003-46456 A

  However, the above-described conventional method of monitoring the optical input level and the bit error rate is a method of monitoring the quality of transmission data, and does not monitor the state of the transmission line. That is, with this method, it is possible to monitor whether or not data has been transmitted correctly, but it is not possible to detect any abnormality that has occurred in the transmission path.

  For example, when a stress (strain) or the like occurs in an optical fiber due to a disaster or the like, the transmission loss increases due to the stress, and the optical input level decreases. The rate of change of the optical input level is the change in the case where the optical output level is lowered due to aging of the optical module (laser diode module, etc.) on the transmitting side, and the optical input level on the receiving side is thereby lowered. Even if it is abrupt compared to the ratio, it is determined that there is no abnormality unless the optical input level exceeds the threshold value, so that it is not possible to detect an abnormality in the transmission path.

  Also, with the method disclosed in Patent Document 1, the transmission path cannot be monitored when the transmission method is not the wavelength division multiplexing method. Furthermore, in addition to monitoring the transmission path, in order to monitor the quality of the original transmission data, it is necessary to monitor the bit error rate of the transmission data, so a double monitoring system is required.

  The present invention provides an optical transmission line monitoring method, an optical transmission line monitoring program, and an optical transmission line monitoring device capable of detecting that an abnormality has occurred in a transmission line in order to solve the above-described problems caused by the conventional technology. For the purpose.

In order to solve the above-described problems and achieve the object, an optical transmission line monitoring method according to the present invention monitors the state of an optical transmission line while receiving an optical signal sent from the transmission side via the optical transmission line. In the optical transmission line monitoring method, the first step of sampling the optical input level at a predetermined period and the rate of change of the optical input level are obtained based on the plurality of optical input levels sampled in the first step. A second step; a third step for detecting an optical transmission line abnormality based on a rate of change in the optical input level obtained in the second step; and the optical input obtained in the second step. And a fourth step of changing a sampling period of the optical input level in accordance with a rate of change of the level, and the first step, the first step with the sampling period changed in the fourth step, Wherein the sequentially performed steps and said third step.

  According to the above configuration, the rate of change of the optical input level is constantly monitored, and when the optical input level changes suddenly even if it is about several dB, it is early detected that an abnormality has occurred in the optical fiber due to the rate of change. Can be detected.

  According to the optical transmission line monitoring method, the optical transmission line monitoring program, and the optical transmission line monitoring apparatus according to the present invention, it is possible to detect that an abnormality has occurred in the transmission line. In particular, there is an effect that even when an abnormality that cannot be detected only by monitoring the quality of transmission data occurs in the optical fiber, the occurrence of the abnormality can be detected.

  First, the principle of the optical transmission line monitoring method of the present invention will be described. FIG. 1 is a schematic diagram showing how the optical input level changes with time in order to explain the principle of the optical transmission line monitoring method according to the present invention. As shown in FIG. 1, the present invention monitors the rate of change of the optical input level on the optical signal receiving side, and when the rate of change of the optical input level exceeds a predetermined threshold, Detects that an abnormality has occurred in the transmission path.

  In general, the reception dynamic range of the optical module on the reception side is 10 to 20 dB or more. On the other hand, when an abnormality due to stress or the like occurs in the optical fiber that is the optical transmission path, it is estimated that the optical input level on the receiving side fluctuates rapidly by about several dB. Therefore, in the conventional configuration in which an alarm is issued only when the optical input level is lower than a certain threshold value (input disconnection alarm issue level) (input disconnection state), an abnormality occurring in the optical fiber is detected at an early stage. It is not possible.

  However, as in the present invention, the rate of change of the optical input level is constantly monitored, and even when the optical input level is about several dB, it is possible to quickly detect that an abnormality has occurred in the optical fiber. Can be detected. Therefore, it is possible to detect an optical fiber abnormality and perform maintenance before an input disconnection state or a state where bit errors frequently occur in received data, so that a highly reliable transmission system can be realized. it can. In addition, you may use together with the system which monitors the conventional optical input level and issues an alarm in the case of an input interruption state.

  FIG. 2 is a block diagram showing a configuration of a communication apparatus including the optical transmission line monitoring apparatus according to the present invention. As shown in FIG. 2, the optical signal transmitted from the transmission unit 11 of the transmission device 1 via the transmission path (optical fiber) 2 is branched into two by the coupler 31 of the reception device 3. One optical signal is sent to the receiving unit 32 and subjected to normal reception processing. The other optical signal is sent to the optical transmission line monitoring device 4.

  In the optical transmission line monitoring device 4, the transmitted optical signal is received at the front stage (photodiode 41) of the receiving means and converted into a current signal corresponding to the optical input level. Then, the current signal is converted into a voltage signal in a subsequent stage (current / voltage conversion unit 42) of the receiving means. The converted voltage signal is sampled at a predetermined sampling period by an analog / digital conversion unit (A / D) 43 serving as a sampling unit, converted into a digital signal, and sent to a monitoring control unit (monitoring control unit 44).

  The monitoring control unit (monitoring control unit 44) obtains the change rate of the light input level based on the values of the plurality of light input levels sampled by the sampling unit (analog / digital conversion unit 43), and the change rate is When the predetermined threshold is exceeded, it is detected that an abnormality has occurred in the optical transmission line (optical fiber 2). The monitoring control means (monitoring control unit 44) is configured by an LSI (Large Scale Integrated Circuit) capable of writing logic such as FPGA (Field Programmable Gate Array). The LSI obtains the rate of change of the optical input level and executes a program for determining whether the rate of change exceeds the threshold value, so that the light transmitted from the transmission side via the optical transmission line is transmitted. A function of monitoring the state of the optical transmission line while receiving a signal is realized.

  FIG. 3 is a block diagram showing the configuration of the optical transmission line monitoring device 4. As shown in FIG. 3, the sampling period of the sampling means (analog / digital converter 43) is variable, and the sampling period is controlled by a sampling reference clock generated by the monitoring controller 44. This is because, depending on the degree of change in the optical input level, it may not be possible to cope with one type of sampling period.

  In other words, if the change in the optical input level is slow, the frequency of the sampling reference clock may be lowered to increase the monitoring time interval, but if the optical input level changes suddenly, the sampling reference clock may be increased. It is necessary to increase the clock frequency to shorten the monitoring time interval. Otherwise, for example, if the monitoring time interval is short as shown in FIG. 4, a rapid change in the light input level can be captured. However, even if the same change occurs, if the monitoring time interval is long as shown in FIG. It looks like a slow change. The broken line in FIG. 5 represents the change in the optical input level in FIG.

  It is preferable in terms of reducing power consumption to lower the frequency of the sampling reference clock when the degree of change in the optical input level is slow. Accordingly, the frequency of the sampling reference clock is lowered during normal times, and when the monitoring control means (monitoring control unit 44) determines that a change in the optical input level has started to appear, the frequency of the sampling reference clock is increased to increase the interval of the monitoring time. May be shortened to prepare for subsequent monitoring of changes in the light input level.

  Further, as shown in FIG. 4, the optical transmission line monitoring device 4 is configured such that the optical input level becomes the input disconnection alarm issue level when the change rate of the optical input level is large when the interval of the monitoring time is constant. Even if it is not reached, an alarm indicating that the severity is severe may be issued. Further, as shown in FIG. 6, the optical transmission line monitoring device 4 may issue an alarm indicating that the severity is mild when the rate of change of the optical input level is small. However, even if the rate of change of the optical input level is small, if the frequency is high, the optical transmission line monitoring device 4 is severe even if the optical input level does not reach the input disconnection alarm issue level. An alarm indicating that may be issued.

  Further, the optical transmission line monitoring device 4 may store the initial optical input level at the time of system startup in an internal memory or the like. In this case, the optical transmission line monitoring device 4 reads the initial optical input level from the memory or the like during system operation, and compares the optical input level during system operation with the initial optical input level. Then, as shown in FIG. 7, the optical transmission line monitoring device 4 issues an alarm even if the optical input level does not reach the input disconnection alarm issue level when the difference becomes a certain level or more. Also good.

  Exemplary embodiments of an optical transmission line monitoring method, an optical transmission line monitoring program, and an optical transmission line monitoring apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings. In the following description, the same components are denoted by the same reference numerals and redundant description is omitted.

(Embodiment 1)
FIG. 8 is a block diagram illustrating a configuration of a communication apparatus including the optical transmission line monitoring apparatus according to the first embodiment. As shown in FIG. 8, the optical transmission line monitoring device 4 includes a photodiode (PD) 41, a current / voltage conversion unit (IV) 42 such as a resistance element, an analog / digital conversion unit (A / D) 43, and supervisory control. A unit 44 and a memory unit 45 are provided. An optical signal transmitted from the transmission unit 11 of the transmission device 1 via the optical fiber 2 is converted into a normal optical signal for reception processing and an optical signal for transmission path monitoring by the coupler (CPL) 31 of the reception device 3. Branch off. The former optical signal is sent to the receiving unit 32 that performs normal reception processing. The latter optical signal is sent to the photodiode 41 of the optical transmission line monitoring device 4.

  The photodiode 41 converts the transmitted optical signal for monitoring the transmission path into a current signal corresponding to the optical input level. The current / voltage conversion unit 42 converts the current signal output from the photodiode 41 into a voltage signal. The analog / digital converter 43 samples the analog voltage signal output from the current / voltage converter 42 at a predetermined sampling period and converts it into a digital signal. The sampling period at this time is determined by the frequency of the sampling reference clock generated by the monitoring control unit 44.

  The supervisory control unit 44 includes a value of an optical input level composed of a digital signal output from the analog / digital conversion unit 43, and a value of the optical input level sampled one time before and stored in the memory unit 45, for example. Find the difference between The difference between the values of the optical input level is the rate of change of the optical input level in the sampling period at that time. Then, the monitoring control unit 44 compares the change rate of the optical input level with a threshold value, and determines that an abnormality has occurred in the optical fiber 2 when the change rate exceeds the threshold value.

  The monitoring control unit 44 is configured by a programmable LSI such as an FPGA, and executes a program for obtaining a change rate of the optical input level and determining whether or not the change rate exceeds a threshold value. By executing the program, the function of monitoring the state of the optical fiber 2 while the optical signal transmitted from the transmission device 1 via the optical fiber 2 is received by the reception unit 32 of the reception device 3 is realized.

  The monitoring control unit 44 generates sampling reference clocks having a plurality of different frequencies. That is, the sampling cycle of the analog / digital conversion unit 43 is variable, and a sudden change in the optical input level is prevented from appearing as a slow change due to the sampling cycle being longer than necessary (see FIG. 4 and FIG. 5). The threshold used by the monitoring control unit 44 for comparison with the change rate of the optical input level is set for each sampling reference clock, that is, for each sampling period, and is stored in the memory unit 45.

  Further, even if the optical input level does not reach the input disconnection alarm issue level, the monitoring control unit 44 issues a transmission line abnormality alarm indicating a serious degree of seriousness when the rate of change of the optical input level is large (FIG. 4). reference). Further, when the rate of change of the optical input level is small, the supervisory control unit 44 issues a transmission line abnormality preliminary alarm indicating a mild severity (see FIG. 6). However, even if the rate of change of the light input level is small, if the frequency is high, an alarm indicating a serious degree of seriousness may be issued even if the light input level does not reach the input break alarm issue level. Good (see FIG. 6).

  In addition, the monitoring controller 44 always compares the value of the optical input level with the value (initial value) of the optical input level sampled for the first time after the system is started. When the difference reaches a certain level or more, an alarm is issued even if the light input level does not reach the input disconnection alarm issue level (see FIG. 7). The initial value of the optical input level is stored in the memory unit 45.

  Next, a program executed by the monitoring control unit 44 will be described. FIG. 9 is a flowchart showing the program. First, in step S1, when the system is activated by turning on the power of the transmission device 1 and the reception device 3, a sampling reference clock to be supplied to the analog / digital conversion unit (A / D) 43 is determined (step S2). Then, the optical input level value (A / D monitor value) sampled by the sampling reference clock is acquired (step S3). If the acquired value of the optical input level is the first value (initial value) after system startup (step S4: Yes), the value is stored in the memory unit 45 (step S16). If it is not the initial value (step S4: No), the process proceeds to the next step S5.

  Subsequently, it is determined whether or not an error (bit error) has occurred in the received data (step S5). If a bit error has occurred (step S5: Yes), the frame synchronization pattern cannot be detected and the head of the frame cannot be identified, so a LOF (Loss of Frame) indicating that the frame is out of frame synchronization or Then, an LOS (Loss of Signal) indicating that the signal is in an input interrupted state where the signal cannot be identified is issued (step S11), and the transmission line monitoring is terminated. Thereafter, the reset is performed when the cause of the bit error is resolved and the optical signal is returned to the normal reception state, and the transmission line monitoring is resumed.

  If no bit error has occurred in step S5 (step S5: No), it is determined whether the optical input level is within a desired range (step S6). If the optical input level deviates from the normal range (step S6: No), an input interruption alarm is issued (step S12), and the transmission line monitoring is terminated. Thereafter, when the cause of the deviation of the optical input level from the normal range is resolved and the optical signal is returned to the normal reception state, the reset is performed and transmission line monitoring is resumed.

  If the optical input level is in the normal range in step S6 (step S6: Yes), the current optical input level value is compared with the previously sampled optical input level value, and the rate of change is determined. It calculates and calculates | requires (step S7). Further, the current optical input level value is compared with the initial value of the optical input level stored in the memory unit 45, and the amount of change from the initial value is calculated (step S8).

  Subsequently, it is determined whether or not the change rate of the light input level obtained in step S7 is within an allowable range (step S9). If the change rate of the optical input level is within the allowable range (step S9: Yes), it is determined whether or not the amount of change from the initial value of the optical input level obtained in step S8 is within the allowable range. Determine (step S10). When the change amount of the optical input level from the initial value is within the allowable range (step S10: Yes), the process returns to step S2 and the above processing is repeated.

  On the other hand, if the rate of change of the optical input level is not within the allowable range in step S9 (step S9: No), a transmission line abnormality alarm indicating a serious seriousness is issued (step S13), and analog / digital The sampling clock value supplied to the conversion unit (A / D) 43 is changed to a higher clock (step S14). And the abnormality of the optical fiber 2 is detected with higher accuracy by repeating the processes in and after step S2 with the changed sampling reference clock. Further, when the change amount of the optical input level from the initial value is out of the allowable range in step S10 (step S10: No), a transmission line abnormality preliminary alarm indicating a mild severity is issued (step S10). S15) The processing from step S2 onward is repeated with the current sampling reference clock, that is, without changing the sampling reference clock.

  According to the first embodiment, by monitoring the change rate of the optical input level, even if the optical input level does not decrease to the extent that the input is interrupted, if the change is abrupt, there is an abnormality in the optical fiber 2. The occurrence can be detected. Therefore, it is possible to detect abnormalities of the optical fiber 2 at an early stage and perform maintenance before the input is interrupted or bit errors occur frequently in the received data, thus realizing a highly reliable transmission system. can do.

(Embodiment 2)
FIG. 10 is a block diagram illustrating a configuration of a communication apparatus including the optical transmission line monitoring apparatus according to the second embodiment. As shown in FIG. 10, in the second embodiment, in addition to the configuration of the first embodiment, a spare optical fiber (backup transmission line) 21 serving as a redundant system is laid between the transmission side and the reception side, In the case where an abnormality occurs in the optical fiber 2 that becomes, the spare optical fiber 21 is used as a transmission line.

  The upstream side of the spare optical fiber 21 is connected to a spare transmitter 12 that is a redundant system. The downstream side of the spare transmitter 12 is connected to a spare coupler (CPL2) 33 provided in the receiver 3. The receiving device 3 has a spare receiving unit 34, and the spare receiving unit 34 receives an optical signal transmitted from the transmitting unit 13 of the spare transmitting device 12 via the spare optical fiber 21. To do.

  In addition, the optical transmission line monitoring device 4 includes a switching unit 49 that selects one of the data output from the standby receiving unit 34 and the data output from the main receiving unit 32 of the first embodiment. ing. As described in the first embodiment, when data is received using the optical signal transmitted from the main transmitter 1 via the main optical fiber 2, the optical fiber 2 is abnormal. Occurs and the light input level changes, the monitoring control unit 44 issues an alarm. Further, the monitoring control unit 44 sends a switching control signal to the switching unit 49 using the issuing of the alarm as a trigger.

  When the switching unit 49 receives the switching control signal from the monitoring control unit 44, the data to be selected as received data is sent from the spare receiving unit 34 from the data sent from the main receiving unit 32 so far. Switch to incoming data. Similarly to the first embodiment, the spare coupler 33 includes a spare photodiode (PD 2) 46 provided as a redundant system in the optical transmission line monitoring device 4, and a spare current / voltage converter (IV 2) 47. Also, a spare analog / digital converter (A / D2) 48 is connected, and after switching to the spare transmission path system side in the switching section 49, the monitoring control section 44 monitors the redundant transmission path. .

  According to the second embodiment, when an abnormality occurs in the main optical fiber 2, the transmission line can be switched to the spare optical fiber 21, so that a more reliable transmission system can be realized. Can do. In the configuration shown in FIG. 10, the main transmission device 1 and the spare transmission device 12 are separated and each includes transmission units 11 and 13. However, the light output from the transmission unit of a single transmission device The signal may be branched and input to the main optical fiber 2 and the spare optical fiber 21.

(Embodiment 3)
FIG. 11 is a block diagram illustrating a configuration of a communication apparatus including the optical transmission line monitoring apparatus according to the third embodiment. As shown in FIG. 11, in addition to the configuration of the first embodiment, the third embodiment is provided with a transmission unit 35 in the reception device 3, and a reception unit 14 and a monitoring control unit 15 are provided in the transmission device 1. When the device 3 issues an alarm due to a change in the optical input level, the transmission unit 35 of the reception device 3 notifies the transmission device 1 of the state of the optical fiber 2 via another transmission line such as another optical fiber 22. It is a thing. Here, according to the first embodiment, one is the transmission device 1 and the other is the reception device 3, but both of them are used as a transmission / reception device or a relay device for transmitting and receiving optical signals, and bidirectional data communication. A transmission system that performs

(Embodiment 4)
FIG. 12 is a block diagram illustrating a configuration of a communication apparatus including the optical transmission line monitoring apparatus according to the fourth embodiment. As shown in FIG. 12, in the fourth embodiment, in addition to the configuration of the first embodiment, a monitoring control unit 15 is provided in the transmission apparatus 1, and the optical output level of the transmission unit 11 is monitored by the monitoring control unit 15. The optical output level information of the transmitter 11 is added to the optical signal sent from the transmitter 11 to the receiver 3. On the receiving side, the monitoring control unit 44 of the optical transmission line monitoring device 4 confirms that there is no abnormality in the transmission unit 11 of the transmission device 1 based on the optical output level information transmitted from the transmission device 1. Determine the rate of change of the light input level. Alternatively, the ratio of the change in the net light input level that does not include the change in the light output level on the transmission side can be obtained on the reception side.

  Next, a program executed by the monitoring control unit 44 will be described. FIG. 13 is a flowchart showing the program. As shown in FIG. 13, it is basically the same as the flowchart of the first embodiment shown in FIG. There are two differences from the first embodiment. The first is that a step of obtaining a value of the light output level on the transmission side (step S21) between step S5 and step S6, and the obtained light output. When the level value is the first value (initial value) after system startup (step S22: Yes), the value is stored in the memory unit 45 (step S25). When the level value is not the initial value (step S22). : No), that is, the processing flow that proceeds to step S6 without being stored in the memory unit 45 is inserted.

  Second, between step S8 and step S9, the current light output level value is compared with the initial value of the light output level stored in the memory unit 45, and the amount of change from that initial value is compared. Is the amount of change from the initial value of the light input level obtained in step S8 calculated by calculating (S23) greater than the amount of change from the initial value of the light output level obtained in step S23? The step of determining whether or not (step S24) is inserted. When the change amount of the light input level is larger than the change amount of the light output level in step S24 (step S24: Yes), the process proceeds to step S9. On the other hand, when the change amount of the light output level is larger than the change amount of the light input level (step S24: No), the process returns to step S2 to repeat the processing from step S2.

  According to the fourth embodiment, after confirming the amount of change in the optical output level on the transmission side, an abnormality has occurred on the transmission side when the optical input level changes by determining the rate of change in the optical input level. Or whether an abnormality has occurred in the optical fiber 2 can be distinguished. Therefore, the abnormality of the optical fiber 2 can be detected with higher accuracy.

  As described above, the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above-described example, the present invention is applied to the receiving device. In addition to this, the optical signal transmitted from the upstream transmitting device is received, and the received optical signal is amplified. It is also possible to apply the present invention to a relay device that performs transmission to a downstream receiving device. In that case, what is necessary is just to replace a receiving device with a relay device by description of embodiment mentioned above.

  The optical transmission line monitoring method described in this embodiment is realized by executing a program prepared in advance by a microcomputer such as an FPGA. This program is recorded in a nonvolatile memory such as an EEPROM. The program may be executed by being read from the memory by a computer, or recorded on a computer-readable recording medium such as a hard disk, a flexible disk, a CD-ROM, an MO, or a DVD, and read from the recording medium by the computer. May be executed by This program may be distributed to the microcomputer via a network such as the Internet.

(Supplementary note 1) In an optical transmission line monitoring method for monitoring the state of an optical transmission line while receiving an optical signal transmitted from the transmission side via the optical transmission line,
A first step of sampling the light input level at a predetermined period;
A second step of determining a rate of change of the light input level based on the plurality of light input levels sampled in the first step;
A third step of detecting an abnormality in the optical transmission line based on the rate of change in the optical input level obtained in the second step;
An optical transmission line monitoring method comprising:

(Appendix 2) A plurality of optical transmission lines are laid between the transmission side and the reception side, and the state of the optical transmission line is monitored while receiving an optical signal transmitted from the transmission side via the optical transmission line. In the optical transmission line monitoring method,
A first step of sampling an input level of an optical signal transmitted via the first optical transmission line at a predetermined period;
A second step of determining a rate of change of the light input level based on the plurality of light input levels sampled in the first step;
An abnormality in the first optical transmission line is detected based on the rate of change in the optical input level obtained in the second step, and an effective optical transmission line between the transmission side and the reception side is determined as the first optical transmission line. A third step of switching from the optical transmission line to the second optical transmission line;
An optical transmission line monitoring method comprising:

(Supplementary Note 3) The method further includes a fourth step of changing a sampling period of the optical input level according to a rate of change of the optical input level obtained in the second step,
3. The optical transmission line monitoring method according to appendix 1 or 2, wherein the first step, the second step, and the third step are sequentially performed with the sampling period changed in the fourth step.

(Additional remark 4) The threshold value of the ratio of the change of an optical input level is set for every sampling period of several optical input levels, The optical transmission line monitoring method of Additional remark 3 characterized by the above-mentioned.

(Additional remark 5) When abnormality of the optical transmission line is detected in the third step, a fifth alarm that issues a severity alarm according to the rate of change of the optical input level obtained in the second step The optical transmission line monitoring method according to any one of appendices 1 to 4, further comprising a step.

(Supplementary note 6) Any one of Supplementary notes 1 to 5, further comprising a sixth step of notifying the transmission side that an abnormality has been detected when an abnormality in the optical transmission path is detected in the third step. The optical transmission line monitoring method according to claim 1.

(Additional remark 7) In the optical transmission line monitoring method which monitors the state of an optical transmission line, receiving the optical signal sent via the optical transmission line from the transmission side,
A first step of sending an optical signal including optical output level information from the transmission side to the reception side via the optical transmission line;
A second step of sampling the optical input level at a predetermined cycle on the receiving side;
A third check for a change in the light output level on the transmission side based on the light output level information and a ratio of the change in the light input level based on the plurality of light input levels sampled in the second step. Steps,
A fourth step of detecting an optical transmission line abnormality based on the rate of change of the optical input level determined in the third step;
An optical transmission line monitoring method comprising:

(Appendix 8) A plurality of optical transmission lines are laid between the transmission side and the reception side, and the state of the optical transmission line is monitored while receiving an optical signal sent from the transmission side via the optical transmission line. In the optical transmission line monitoring method,
A first step of sending an optical signal including optical output level information from the transmission side to the reception side via each optical transmission line;
A second step of sampling an input level of an optical signal transmitted via the first optical transmission line at a receiving side at a predetermined period;
A third check for a change in the light output level on the transmission side based on the light output level information and a ratio of the change in the light input level based on the plurality of light input levels sampled in the second step. Steps,
An abnormality in the first optical transmission line is detected based on the rate of change in the optical input level obtained in the third step, and an effective optical transmission line between the transmission side and the reception side is determined as the first optical transmission line. A fourth step of switching from the optical transmission line to the second optical transmission line;
An optical transmission line monitoring method comprising:

(Supplementary note 9) A first step of obtaining a rate of change of the light input level based on a plurality of light input levels sampled at a predetermined cycle, and a light input level obtained in the first step. The second step of detecting an abnormality in the optical transmission line based on the rate of change is executed to monitor the state of the optical transmission line while receiving the optical signal sent from the transmission side via the optical transmission line. An optical transmission line monitoring program for realizing the functions.

(Appendix 10) An optical transmission line monitoring device that monitors the state of an optical transmission line while receiving an optical signal transmitted from the transmission side via the optical transmission line,
Receiving means for receiving an optical signal and converting the optical signal into an electrical signal corresponding to an input level;
Sampling means for sampling the electrical signal output from the receiving means at a predetermined period;
A monitoring control means for obtaining a rate of change of the optical input level based on a plurality of values sampled by the sampling means, and detecting an abnormality in the optical transmission line based on the rate of change;
An optical transmission line monitoring device comprising:

(Appendix 11) A plurality of optical transmission paths are laid between the transmission side and the reception side, and the state of the optical transmission path is monitored while receiving an optical signal transmitted from the transmission side via the optical transmission path. An optical transmission line monitoring device,
First receiving means for receiving an optical signal sent via the first optical transmission line and converting the optical signal into an electrical signal corresponding to the input level;
First sampling means for sampling the electrical signal output from the first receiving means at a predetermined period;
Second receiving means for receiving an optical signal sent via the second optical transmission line and converting the optical signal into an electric signal corresponding to the input level;
Second sampling means for sampling the electrical signal output from the second receiving means at a predetermined period;
Monitoring control means for obtaining a change rate of the optical input level based on a plurality of values sampled by the first sampling means, and detecting an abnormality of the first optical transmission line based on the change rate;
When the monitoring control means detects an abnormality in the first optical transmission line, an effective optical transmission line between the transmission side and the reception side is changed from the first optical transmission line to the second optical transmission line. Switching means for switching;
An optical transmission line monitoring device comprising:

(Additional remark 12) The said monitoring control means changes the sampling period of the said sampling means according to the ratio of the change of the calculated | required optical input level, the value of the optical input level sampled by the changed sampling period, and after change 12. The optical transmission line monitoring device according to appendix 10 or 11, wherein the optical transmission line monitoring apparatus has a function of detecting an abnormality of the optical transmission line by comparing with a threshold value corresponding to the sampling period.

(Supplementary note 13) An optical transmission line monitoring device for monitoring the state of an optical transmission line while receiving an optical signal transmitted from the transmission side via the optical transmission line,
Monitoring the output level of the optical signal sent from the transmitting side to the receiving side, and transmitting side monitoring control means for including the optical output level information in the optical signal sent to the receiving side;
Receiving means for receiving an optical signal sent from the transmitting side and converting the optical signal into an electrical signal corresponding to the input level;
Sampling means for sampling the electrical signal output from the receiving means at a predetermined period;
Based on the optical output level information, a change in the optical output level on the transmission side is confirmed, and a rate of change in the optical input level is obtained based on a plurality of values sampled by the sampling means, and based on the rate of the change Receiving side monitoring control means for detecting an optical transmission line abnormality,
An optical transmission line monitoring device comprising:

  As described above, the optical transmission line monitoring method, the optical transmission line monitoring program, and the optical transmission line monitoring apparatus according to the present invention are useful for optical communication technology, and are particularly suitable for monitoring transmission lines such as optical fibers. ing.

It is a schematic diagram for demonstrating the principle of the optical transmission line monitoring method concerning this invention. It is a block diagram which shows the structure of the communication apparatus containing the optical transmission line monitoring apparatus concerning this invention. It is a block diagram which shows the structure of the optical transmission line monitoring apparatus concerning this invention. It is a schematic diagram for demonstrating the appearance of the change of the optical input level when the monitoring time interval is short. It is a schematic diagram for demonstrating the appearance of the change of the optical input level when the monitoring time interval is long. It is a schematic diagram for demonstrating the relationship between the mode of a change of an optical input level, and an alarm issue level. It is a schematic diagram for demonstrating the relationship between the mode of a change of an optical input level, and an alarm issue level. 2 is a block diagram illustrating a configuration of a communication apparatus including the optical transmission line monitoring apparatus according to the first embodiment. FIG. 3 is a flowchart illustrating an optical transmission line monitoring method according to the first embodiment. 6 is a block diagram illustrating a configuration of a communication apparatus including an optical transmission line monitoring apparatus according to a second embodiment. FIG. 6 is a block diagram illustrating a configuration of a communication apparatus including an optical transmission line monitoring apparatus according to Embodiment 3. FIG. FIG. 10 is a block diagram illustrating a configuration of a communication device including an optical transmission line monitoring device according to a fourth embodiment. 10 is a flowchart illustrating an optical transmission line monitoring method according to a fourth embodiment.

Explanation of symbols

2 Transmission path 4 Optical transmission path monitoring device 41, 42 Receiving means 43 Sampling means 44 Monitoring control means

Claims (6)

In the optical transmission line monitoring method for monitoring the state of the optical transmission line while receiving the optical signal sent from the transmission side via the optical transmission line,
A first step of sampling the light input level at a predetermined period;
A second step of determining a rate of change of the light input level based on the plurality of light input levels sampled in the first step;
A third step of detecting an abnormality in the optical transmission line based on the rate of change in the optical input level obtained in the second step;
A fourth step of changing a sampling period of the light input level in accordance with a rate of change of the light input level obtained in the second step,
An optical transmission line monitoring method, wherein the first step, the second step, and the third step are sequentially performed with the sampling period changed in the fourth step.   2. The optical transmission line monitoring method according to claim 1, wherein a threshold value of a rate of change of the optical input level is set for each sampling period of the plurality of optical input levels.   The method further includes a fifth step of issuing a warning of a severity corresponding to the rate of change of the optical input level obtained in the second step when an abnormality in the optical transmission line is detected in the third step. 3. The optical transmission line monitoring method according to claim 1, wherein the optical transmission line is monitored.   4. The method according to claim 1, further comprising: a sixth step of notifying the transmission side that an abnormality has been detected when an abnormality in the optical transmission path is detected in the third step. 5. An optical transmission line monitoring method according to claim 1. In the optical transmission line monitoring program for monitoring the state of the optical transmission line while receiving the optical signal sent from the transmission side via the optical transmission line,
On the computer,
A first step of sampling the light input level at a predetermined period;
A second step of determining a rate of change of the light input level based on the plurality of light input levels sampled in the first step;

A third step of detecting an abnormality in the optical transmission line based on the rate of change in the optical input level obtained in the second step;
And a fourth step of changing the sampling period of the light input level according to the rate of change of the light input level obtained in the second step,
An optical transmission line monitoring program that causes the first step, the second step, and the third step to be sequentially performed with the sampling period changed in the fourth step. An optical transmission line monitoring device that monitors the state of an optical transmission line while receiving an optical signal sent from the transmission side via the optical transmission line,
Receiving means for receiving an optical signal and converting the optical signal into an electrical signal corresponding to an input level;
Sampling means for sampling the electrical signal output from the receiving means at a predetermined period;
Obtaining a rate of change of the optical input level based on a plurality of values sampled by the sampling means, and comprising a monitoring control means for detecting an abnormality in the optical transmission line based on the rate of change,
The supervisory control unit changes the sampling period of the sampling unit according to the obtained change rate of the optical input level, and the change rate of the optical input level sampled in the changed sampling period and the changed sampling rate An optical transmission line monitoring apparatus having a function of detecting an abnormality in an optical transmission line by comparing with a threshold corresponding to a cycle.

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