JP2005318567A - Optical transmission system, optical repeating apparatus and quality supervising method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmission system, optical repeating apparatus and quality supervising method in which an instantaneous level variation can be defected and the level variation can be efficiently stored. <P>SOLUTION: An optical transmission system of the present invention includes means (107, 113, and the like) for detecting a quality deterioration of an optical signal using a quality deterioration detecting means (403 or the like) installed in an optical terminal station or the like and transferring the quality deterioration to an optical repeating apparatus (102 or the like) as a supervisory signal. The optical repeating apparatus includes a level variation detecting means (202 or the like) for detecting a level of the optical signal and a level variation storing means (202 or the like) for storing information of the detection. The level variation storing means sequentially discards the level variation information having passed a predetermined period while storing the information in a constant interval, and holds storage of the level variation information from a time of storage of the level variation information based on a particular optical signal until a time controlled by the supervisory signal based on a quality deterioration of the optical signal transferred by the transfer means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to optical transmission communication, and more particularly to an optical transmission system, an optical repeater, and a quality monitoring method thereof, to which one or more optical repeaters are connected.

  In an optical transmission system, a communication company, a communication equipment maintenance and operation company, etc. need to find and repair a failure location that causes the quality deterioration of a service signal.

  However, the conventional optical transmission system has a problem that it is difficult to specify the cause or failure location when the level fluctuation caused by the quality deterioration of the service signal is instantaneous. As an example of causing an instantaneous level fluctuation, there is a case where stress is applied to the optical fiber during a work operation in the optical terminal station.

  FIG. 9 shows a configuration of a conventional optical amplification repeater transmission system. In FIG. 9, reference numerals 901-1 to 901-n denote optical transmitters, 902 to 905 denote optical amplifiers, 906-1 to 906-n denote optical receivers, 908 denotes a wavelength multiplexer, 909 denotes a wavelength divider, and 910 to 912. Is an optical fiber transmission line, and 921 and 922 are optical terminals.

  Next, the operation of the conventional optical amplification repeater transmission system will be described with reference to FIG.

Optical transmitters 901-1 to 901-n in FIG. 9 output optical signals set to predetermined wavelengths λ ₁ , λ ₂ ,..., Λ _n in order to perform wavelength multiplexing. The output optical signals λ ₁ , λ ₂ ,..., Λ _n are wavelength-multiplexed by the wavelength multiplexer 908. The wavelength-multiplexed optical signals λ _{1 to} λ _n are collectively amplified by the optical amplifier 902 and output to the optical fiber transmission line 910. The output wavelength multiplexed optical signals λ _{1 to} λ _n are sequentially amplified by the optical amplifiers 903 to 905 while being transmitted through the optical fiber transmission lines 910 to 912. Thereby, the loss generated in the immediately preceding optical fiber transmission line is compensated. Wavelength-multiplexed optical signals lambda ₁ to [lambda] _n that is compensated for the loss is wavelength division at a wavelength splitter 909, a single wavelength lambda _1, lambda _2, · · ·, it is divided into optical signals of lambda _n. Each of the divided optical signals λ ₁ , λ ₂ ,..., Λ _n is received by the optical receivers 906-1 to 906-n. As described above, this conventional optical amplification repeater transmission system realizes optical amplification repeater transmission by wavelength-multiplexing a plurality of optical signals through one optical fiber transmission line.

  FIG. 10 shows a time chart when a failure occurs in the conventional optical amplification repeater transmission system. When a loss occurs in the optical signal due to disturbances to the optical fiber transmission lines 910 to 912 (for example, an increase in loss due to an external pressure applied to the optical fiber) or a failure of the optical amplifiers 902 to 905, the power of the optical signal The waveform 1001 causes a level fluctuation 1003 with respect to the time axis. The time during which the level fluctuation 1003 occurs may be from the order of 100 msec to about 1 msec if it is short.

  As a method for monitoring a bit error caused by such a change in the optical signal at the optical terminal on the receiving side, a method as described in Non-Patent Document 1 is known.

ITU-T Recommendation G. 783

  In order to detect such a failure as described above, in the conventional optical amplification repeater transmission system, means for detecting the level of the transmitted optical signal is installed in each optical amplifier. Thus, the level of the optical signal is monitored. However, in the conventional optical amplification repeater transmission system, there is a limit to the amount of memory for storing the monitoring information and the time that can be stored. Therefore, as shown in FIG. 10, the interval (detection interval) Ts between the monitoring points 1002 is normally set to about several tens of minutes. Therefore, when an instantaneous level fluctuation of about 1 msec order to 100 msec order such as the level fluctuation 1003 occurs at a time other than the monitoring point 1002, the level fluctuation cannot be detected. Therefore, even if the signal quality deteriorates at the receiving end, it is difficult to specify the cause and the location of the cause.

  In other words, the optical signal level is detected by the optical signal level detection means installed in each of the optical amplifiers 902 to 905. The detection information is accumulated in a memory installed in each optical amplifier. If the interval (detection interval) between the monitoring points 1002 in the detection means is made as short as possible, instantaneous light level fluctuations are not overlooked. However, the memory storage amount is limited and the storage period is also limited. Therefore, if the detection interval is shortened, the detection amount exceeds the storage capacity of the memory. Therefore, the detection interval can usually be set to only about several tens of minutes, and it is difficult to detect instantaneous level fluctuations. FIG. 10 shows an example in which level fluctuation 1003 occurs during the detection interval Ts (about several tens of minutes) as an example in which detection is not possible.

  Even if such an instantaneous level fluctuation occurs, this level fluctuation causes a bit error at the optical receiving end. Therefore, there has been a demand for a method for detecting an instantaneous level fluctuation in each optical amplifier installed in the optical fiber transmission line which is the preceding stage.

  An object of the present invention is to provide an optical transmission system, an optical repeater, and a quality monitoring method thereof capable of detecting instantaneous level fluctuations and storing the level fluctuations efficiently.

  The optical transmission system of the present invention is an optical transmission system in which an optical repeater and an optical receiver are connected to an optical fiber transmission line, and a monitoring signal based on quality degradation of an optical signal detected by the optical receiver is Transfer means for transferring from the optical receiver to the optical repeater is provided. The optical repeater apparatus includes an optical level fluctuation detection unit that detects a level fluctuation of an optical signal, and a level fluctuation storage unit that stores information on the level fluctuation. A quality deterioration detection unit for detecting deterioration is provided. The level variation storage unit sequentially discards the level variation information that has passed a predetermined period while storing the level variation information at regular intervals, and stores the level variation information of a specific optical signal. From this time point, the monitoring signal based on the specific optical signal is transferred by the transfer means, and the storage of the level fluctuation information is held until the time point when the level fluctuation storage unit is controlled. Yes.

  As described above, in the optical transmission system of the present invention, the quality deterioration detection unit of the optical receiving apparatus detects the quality deterioration of the optical signal as needed, and when detecting the quality deterioration due to a specific optical signal, A monitoring signal based thereon is transferred from the optical receiver to the optical repeater by the transfer means. On the other hand, the level fluctuation storage unit of the optical repeater stores the level fluctuation information of the optical signal at regular intervals, and sequentially discards it after a predetermined period, and stores the level fluctuation information of a specific optical signal. From the time point to the time point when the monitoring signal based on the specific optical signal is transferred and controlled by the transfer means, the storage of the level variation information is held.

  Therefore, the optical transmission system of the present invention sequentially discards the level fluctuation information unnecessary for specifying the cause of failure, and holds only the level change information required for specifying the cause of failure. Therefore, it becomes possible to identify the cause of the failure and the location of the failure, and in this way, the level variation information is efficiently held. Therefore, even if the storage interval is shortened, the capacity for holding it can be reduced. Therefore, it is possible to capture an instantaneous level fluctuation that causes a failure without increasing the storage capacity.

  Alternatively, the optical transmission system of the present invention includes at least one optical repeater that relays an optical signal, an optical fiber transmission path that transmits the optical signal, an optical receiver that receives the optical signal, and the optical receiver. And a supervisory signal transfer path for transferring a supervisory signal based on the optical signal received at the optical repeater. The optical repeater apparatus includes: an optical level fluctuation detection unit that detects a level fluctuation of the optical signal; a first monitoring control unit that monitors the level fluctuation and transmits the level fluctuation information; and the level fluctuation information And a level fluctuation storage unit for storing. The optical receiver includes a quality deterioration detection unit that detects quality deterioration of the optical signal transmitted through the optical fiber transmission line, and a second monitoring control unit that monitors the quality deterioration and transmits the monitoring signal as a monitoring signal. And a monitoring signal transfer unit that transfers the monitoring signal from the second monitoring control unit to the first monitoring control unit via the monitoring signal transfer path. The first monitoring control unit controls storage of the level variation storage unit based on the received monitoring signal. The level fluctuation storage unit sequentially discards the level fluctuation information that has passed a predetermined period while storing the level fluctuation information at regular intervals, and from the time when the level fluctuation information of a specific optical signal is stored. The level variation information is stored until the time point controlled by the first monitoring control unit by the monitoring signal based on the specific optical signal.

  As described above, in the optical transmission system of the present invention, the quality deterioration detection unit of the optical receiving apparatus detects the quality deterioration of the optical signal as needed, and when detecting the quality deterioration due to a specific optical signal, A monitoring signal based thereon is transferred from the optical receiver to the optical repeater by the transfer means. On the other hand, the level fluctuation storage unit of the optical repeater stores the level fluctuation information of the optical signal at regular intervals, and sequentially discards it after a predetermined period, and stores the level fluctuation information of a specific optical signal. From the time point to the time point that is controlled by the first monitoring control unit by the monitoring signal based on the specific optical signal, the storage of the level variation information is held.

  Therefore, the optical transmission system of the present invention sequentially discards the level fluctuation information unnecessary for specifying the cause of failure, and holds only the level change information required for specifying the cause of failure. Since the level variation information is efficiently held in this way, even if the storage interval is shortened, the capacity for holding it can be reduced. Therefore, it is possible to capture an instantaneous level fluctuation that causes a failure without increasing the storage capacity.

  An optical repeater of the present invention is connected to an optical fiber transmission line, and includes an optical level fluctuation detecting unit that detects a level fluctuation of an optical signal, and a level fluctuation storage unit that stores information on the level fluctuation. . The level fluctuation storage unit sequentially discards the level fluctuation information after a predetermined period while storing the level fluctuation information at a constant interval, but based on a monitoring signal received from the outside. The level variation information stored at that time is retained without being discarded.

  As described above, in the optical repeater of the present invention, the level variation storage unit stores the level variation information of the optical signal at regular intervals and sequentially discards it after a predetermined period. Here, when a monitoring signal is received from the outside, the level fluctuation storage unit holds the level fluctuation information stored at that time without discarding. Therefore, the optical repeater of the present invention sequentially discards the level fluctuation information that is unnecessary for identifying the cause of the failure, and holds only the level fluctuation information that is necessary for identifying the cause of the failure. Therefore, it becomes possible to identify the cause of the failure and the location of the failure, and in this way, the level variation information is efficiently held. Therefore, even if the storage interval is shortened, the capacity for holding it can be reduced. Therefore, instantaneous level fluctuations that cause failures can be captured without increasing the storage capacity.

  Alternatively, the optical repeater of the present invention is connected to an optical fiber transmission line, and an optical level fluctuation detecting unit that detects a level fluctuation of an optical signal and monitoring control that monitors the level fluctuation and transmits it as level fluctuation information And a level variation storage unit for storing the level variation information. The level variation storage unit sequentially discards the level variation information after a predetermined period while storing the level variation information at a constant interval. In addition, when the monitoring control unit receives a monitoring signal from the outside, the monitoring control unit performs control so that the level variation information stored in the level variation storage unit at that time is retained without being discarded.

  As described above, in the optical repeater of the present invention, the level fluctuation storage unit stores the level fluctuation information of the optical signal at regular intervals, and sequentially discards it after a predetermined period. Here, when the monitoring control unit receives a monitoring signal from the outside, the monitoring control unit performs control so that the level variation information stored in the level variation storage unit at that time is retained without being discarded. Therefore, the optical repeater of the present invention sequentially discards the level fluctuation information that is unnecessary for identifying the cause of the failure, and holds only the level fluctuation information that is necessary for identifying the cause of the failure. Therefore, it becomes possible to identify the cause of the failure and the location of the failure, and in this way, the level variation information is efficiently held. Therefore, even if the storage interval is shortened, the capacity for holding it can be reduced. Therefore, instantaneous level fluctuations that cause failures can be captured without increasing the storage capacity.

  The optical transmission system or the optical repeater of the present invention may have the following features.

  The fixed interval for storing the level variation information in the level variation storage unit is shorter than the time during which the level variation that causes quality degradation occurs in the optical transmission system.

  The storage period of the level fluctuation information in the level fluctuation storage unit is the quality deterioration detection unit for the specific optical signal after the level fluctuation is detected by the optical level fluctuation detection unit and the level fluctuation information is stored in the level fluctuation storage unit. The time until the quality degradation is detected at the time, and the quality degradation detection unit detects the quality degradation, and then the monitoring signal is transferred through the monitoring signal transfer path, and the first monitoring control unit stores the level fluctuation storage unit. It is longer than the sum of the time until control.

  Alternatively, the storage capacity of the level variation information in the level variation storage unit is the quality degradation of the specific optical signal after the level variation is detected by the optical level variation detection unit and the level variation information is stored in the level variation storage unit. The time until the quality degradation is detected by the detection unit, and the quality degradation detection unit detects the quality degradation, and then the monitoring signal is transferred through the monitoring signal transfer path, and the first monitoring control unit It is larger than the sum of the data amount of the detected level fluctuations within the total time until the storage is controlled.

  The quality degradation detection unit includes an optical level detection unit that detects the level of the optical signal and a signal quality detection unit that detects the quality of the optical signal. The signal quality detection unit detects a reception signal loss, a frame synchronization of the reception signal, or a bit error of the reception signal.

  The level fluctuation storage unit can read level fluctuation information from the outside. The level variation storage unit is a memory. Further, the memory includes a primary memory that stores the level variation information for a predetermined time and a secondary memory that stores the level variation information transferred from the primary memory when the monitoring signal is received.

  The optical repeater further includes an optical amplifier. The optical repeater further includes a state detection unit that detects the state of the optical amplification unit.

  In the optical transmission system, wavelength division multiplexing transmission is performed. A quality deterioration detection unit is provided for each individual wavelength. In addition, a wavelength divider is provided that divides the wavelength-multiplexed optical signal into optical signals of individual wavelengths and inputs them to each quality deterioration detection unit.

  The optical transmission system further includes an operation terminal that monitors the optical repeater. Further, an interface for connecting the operation terminal and the optical repeater is provided.

  In the optical transmission system, a counter line is used as a monitoring signal transfer path. Further, a monitoring wavelength signal transfer unit that transmits a monitoring signal to the opposite line is provided.

  The optical transmission system further has an optical cross-connect function. Further, a matrix optical switch for switching the transmission path is provided.

  According to the quality monitoring method of the optical transmission system of the present invention, the optical repeater and the optical receiver are connected to the optical fiber transmission line, the optical level fluctuation detecting step for detecting the level fluctuation of the optical signal, and the level fluctuation information A level fluctuation storing step for storing the optical signal, a quality deterioration detecting step for detecting quality deterioration of the optical signal transmitted through the optical repeater and the optical fiber transmission line, and a monitoring signal based on the quality deterioration of the optical signal. A monitoring signal transfer step for transferring to the level fluctuation storing step. The level fluctuation storage step sequentially discards the level fluctuation information that has passed a predetermined period while storing the level fluctuation information at regular intervals, and information on the level fluctuation of a specific optical signal. The level variation information is stored from the time when the signal is stored to the time controlled by the monitoring signal based on the specific optical signal.

  As described above, in the quality monitoring method of the present invention, the level fluctuation information of the optical signal is stored at regular intervals in the level fluctuation storage step, and is sequentially discarded after a predetermined period. The level fluctuation storage step holds the storage of the level fluctuation information from the time point when the level fluctuation information of the specific optical signal is stored until the time point controlled by the monitoring signal based on the specific optical signal. Therefore, the quality monitoring method of the present invention sequentially discards the level fluctuation information unnecessary for specifying the cause of the failure, and retains the level fluctuation information necessary for specifying the cause of the failure. Therefore, it becomes possible to identify the cause of the failure and the location of the failure, and in this way, the level variation information is efficiently held. Therefore, even if the storage interval is shortened, the capacity for holding it can be reduced. Therefore, it is possible to capture an instantaneous level fluctuation that causes a failure without increasing the storage capacity.

  Alternatively, the quality monitoring method of the optical transmission system of the present invention, the optical repeater is connected to the optical fiber transmission line, the optical level fluctuation detecting step for detecting the level fluctuation of the optical signal, and the level fluctuation by monitoring the level fluctuation A first monitoring step to transmit as variation information, a level variation storage step to store the level variation information, and a quality to detect quality degradation of the optical signal transmitted through the optical repeater and the optical fiber transmission line A deterioration detection step, a second monitoring step of monitoring the quality deterioration and transmitting it as a monitoring signal, and a monitoring signal transfer step of transferring the monitoring signal from the second monitoring step to the first monitoring step. I have. The first monitoring step controls the storage of the level fluctuation storage step based on the received monitoring signal, and the level fluctuation storage step stores the level fluctuation information at regular intervals. The level fluctuation information after a predetermined period is sequentially discarded, and the level fluctuation information of the specific optical signal is stored in the first monitoring step by the monitoring signal based on the specific optical signal. The storage of the level variation information is held until the time of control.

  As described above, in the quality monitoring method of the present invention, the level fluctuation information of the optical signal is stored at regular intervals in the level fluctuation storage step, and is sequentially discarded after a predetermined period. The level variation storage step stores the level variation information from the time when the level variation information of the specific optical signal is stored until the time point controlled by the first monitoring step by the monitoring signal based on the specific optical signal. keeping. Therefore, level fluctuation information unnecessary for identifying the cause of failure is sequentially discarded, and level fluctuation information necessary for identifying the cause of failure is retained. Therefore, it becomes possible to identify the cause of the failure and the location of the failure, and in order to efficiently retain the level variation information in this way, even if the storage interval is shortened, the capacity for retaining it can be reduced. Therefore, it is possible to capture instantaneous level fluctuations that cause failures without increasing the storage capacity.

  The optical transmission system, optical repeater, and quality monitoring method of the present invention have the following effects.

  When quality degradation related to a certain optical signal is detected by the optical receiver, the level variation information related to the same optical signal is stored in each optical repeater, so it becomes possible to investigate the cause of failure and the location of the failure. . In addition, level fluctuations that are not necessary for identifying the cause of failure or failure location are discarded in order, so that necessary level fluctuations are efficiently maintained, so even if the storage interval is shortened, the required level fluctuations The capacity of the storage unit or the level fluctuation storage step is small. Therefore, instantaneous level fluctuations can be captured without increasing the storage capacity.

  A schematic embodiment of an optical transmission system according to the present invention includes one or more optical repeaters that relay optical signals, an optical fiber transmission path that transmits optical signals, an optical receiver that receives optical signals, And a monitoring signal transfer path for transferring a monitoring signal based on the optical signal received by the receiving device to the optical repeater. The optical repeater apparatus includes an optical level fluctuation detecting unit that detects a level fluctuation of the optical signal, a first monitoring control unit that monitors the level fluctuation and transmits the level fluctuation information, and a level that stores the level fluctuation information. And a fluctuation storage unit. The optical receiver includes a quality degradation detection unit that detects quality degradation of an optical signal transmitted through the optical fiber transmission line, a second monitoring control unit that monitors the quality degradation and transmits the monitoring signal, and a monitoring signal. A monitoring signal transfer unit that transfers the signal from the second monitoring control unit to the first monitoring control unit via the monitoring signal transfer path. The first monitoring control unit controls the storage of the level fluctuation storage unit based on the received monitoring signal. The level fluctuation storage unit sequentially discards the level fluctuation information after a predetermined period while storing the level fluctuation information at regular intervals, and specifies the level fluctuation information of the specific optical signal from the time when the level fluctuation information is stored. Until the time when the first monitoring control unit controls the monitoring signal based on the optical signal, the storage of the level variation information is held.

  The storage period of the level fluctuation information in the level fluctuation storage unit is the quality deterioration detection unit for the specific optical signal after the level fluctuation is detected by the optical level fluctuation detection unit and the level fluctuation information is stored in the level fluctuation storage unit. The time until the quality degradation is detected at the time, and the quality degradation detection unit detects the quality degradation, and then the monitoring signal is transferred through the monitoring signal transfer path, and the first monitoring control unit stores the level fluctuation storage unit. It is longer than the sum of the time until control.

  Alternatively, the storage capacity of the level variation information in the level variation storage unit is the quality degradation of the specific optical signal after the level variation is detected by the optical level variation detection unit and the level variation information is stored in the level variation storage unit. The time until the quality degradation is detected by the detection unit, and the quality degradation detection unit detects the quality degradation, and then the monitoring signal is transferred through the monitoring signal transfer path, and the first monitoring control unit It is larger than the sum of the data amount of the detected level fluctuations within the total time until the storage is controlled.

  Further, the level fluctuation storage unit is set to store the level fluctuation at an interval shorter than the level fluctuation detected as the quality deterioration by the quality deterioration detection unit.

  As a result, in the optical transmission system of the present invention, the level fluctuation is stored at an interval shorter than the level fluctuation detected as the quality degradation by the quality degradation detection means, and therefore the level fluctuation causing the quality degradation is reliably identified. be able to. Further, since the level fluctuation information is stored in one or more optical repeaters, it is possible to easily identify the fault location and the fault location. Also, within the time from when the quality degradation information is detected by the quality degradation detection means until the quality degradation information is transferred to the optical repeater, than the detection amount detected by the level fluctuation detection means, Since the storage amount of the level fluctuation storage means is increased, it is possible to easily identify the level fluctuation causing the quality degradation. Further, since it is only necessary to store the level fluctuation information for a limited time, the storage amount of the level fluctuation storage means can be reduced.

  Hereinafter, detailed embodiments of the present invention will be described with reference to the drawings.

    The configuration of the optical transmission system according to the first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a configuration of an optical transmission system according to a first embodiment of the present invention. This optical transmission system includes optical transmitters 101-1 to 101-n, optical amplifiers 102 to 105, optical receivers 106-1 to 106-n as examples of optical repeaters, a supervisory signal transfer unit 107, and a wavelength multiplexer 108. , A wavelength divider 109, optical fiber transmission lines 110 to 112, and a monitoring signal transfer path 113. 121 and 122 are optical terminals. FIG. 1 shows an example in which the number of optical amplifiers is four. The number of optical amplifiers increases or decreases according to the transmission distance. FIG. 1 shows an application example to a wavelength division multiplexing optical transmission system, but the present invention is also applicable to a single wavelength optical transmission system.

  FIG. 2 shows the configuration of the optical amplifiers 102 to 105 shown in FIG. These optical amplifiers 102 to 105 include an optical amplification unit 201, optical level detection units 202 and 203, an optical amplification unit state detection unit 204, a monitoring control unit 205, and a memory 206.

  FIG. 3 shows a configuration of the optical transmitters 101-1 to 101-n shown in FIG. Each of these optical transmitters 101-1 to 101-n includes an optical-electric (O / E) converter 301 and an electric-optical (E / O) converter 302.

  FIG. 4 shows the configuration of the optical receivers 106-1 to 106-n shown in FIG. The optical receivers 106-1 to 106-n include an optical-electrical (O / E) converter 401, an electric-optical (E / O) converter 402, an optical level detector 403, a signal quality detector 404, and supervisory control. Part 405.

  Next, the operation of the optical transmission system according to the first embodiment of the present invention will be described with reference to FIGS. First, the operation of an optical signal in optical repeater transmission will be described. In FIG. 1, optical signals 1 to n input to optical transmitters 101-1 to 101-n are once converted into electrical signals by an O / E converter 301 shown in FIG. Then, the E / O conversion unit 302 converts the signal into an optical signal again. The optical signals output from the E / O converter 302 are set to different predetermined wavelengths in order to be wavelength multiplexed by the wavelength multiplexer 108. Note that the optical transmitters 101-1 to 101-n are not necessarily provided with the O / E converter 301 and do not have to have a function of converting an optical signal into an electrical signal. In that case, an electrical signal is input to the optical transmitters 101-1 to 101-n.

Next, the optical signals λ ₁ , having different wavelengths output from the optical transmitters 101-1 to 101 -n.
λ ₂ ,..., λ _n are wavelength multiplexed by the wavelength multiplexer 108 to become wavelength multiplexed optical signals λ _{1 to} λ _n . The wavelength multiplexed optical signals λ _{1 to} λ _n are collectively amplified by the optical amplifier 102 and output to the optical fiber transmission line 110. Further, the wavelength multiplexed optical signals λ _{1 to} λ _n transmitted through the optical fiber transmission line 110 are amplified by the optical amplifiers 103 to 105, respectively. Thereby, the loss generated in the immediately preceding optical fiber transmission lines 110 to 112 is compensated. Then, the wavelength-multiplexed optical signal lambda ₁ to [lambda] _n is wavelength division at a wavelength divider 109, optical signals lambda ₁ single wavelength, lambda _2, · · ·, are separated into lambda _n. The separated single-wavelength optical signals λ ₁ , λ ₂ ,..., Λ _n are received by the optical receivers 106-1 to 106-n. The received optical signals λ ₁ , λ ₂ ,..., Λ _n are once converted into electrical signals by the O / E converter 401 shown in FIG. 4 and subjected to predetermined treatment such as waveform correction. The Further, the electrical signal is converted again to an optical signal by the E / O conversion unit 402 and output as necessary. The optical receivers 106-1 to 106-n are not necessarily provided with the E / O conversion unit 402, and may not have a function of converting an electrical signal into an optical signal. In that case, electrical signals are output from the optical receivers 106-1 to 106-n. As described above, in the first embodiment of the present invention, optical repeater transmission is realized through a single optical fiber transmission line by wavelength multiplexing a plurality of optical signals.

  Next, the operation relating to the supervisory control system of the optical transmission system of the first embodiment of the present invention will be described. As shown in FIG. 4, the optical level detector 403 installed in each of the optical receivers 106-1 to 106-n detects the level fluctuation of the received optical signal. Further, the signal quality detection unit 404 detects quality degradation such as a bit error of the received optical signal. This bit error is detected by a parity signal (for example, Bit Interleaved Parity information (1) of Synchronous Digital Hierarchy) preliminarily included in the header of a signal to be transmitted or a code rule violation (for example, Gigabit Ethernet (registered trademark)). ) Signal, 10 Giganet Ethernet (registered trademark) signal, etc., 8B10B code, 64B / 66B code, etc.). A detailed description of signal quality detection is omitted. The signals from the light level detection unit 403 and the signal quality detection unit 404 are output to the monitoring control unit 405. The monitoring control unit 405 monitors these signals and outputs them as monitoring signals (quality degradation information) to the monitoring signal transfer path 113 via the monitoring signal transfer unit 107 shown in FIG. Further, the monitoring signal output to the monitoring signal transfer path 113 is transferred to each of the optical amplifiers 102 to 105.

  As shown in FIG. 2, the light level fluctuations are detected in the light level detectors 202 and 203 installed in the optical amplifiers 102 to 105, respectively. The fluctuation of the optical level is caused by a disturbance (for example, an increase in loss caused by an external pressure applied to the optical fiber) received by the transmitted wavelength multiplexed optical signals in the preceding optical fiber transmission lines 110 to 112. Further, the state detection unit 204 of the optical amplification unit detects a change in the state of the optical amplification unit 201 (for example, a failure of a pump laser or a current change). These pieces of detection information are sent to the monitoring control unit 205 together with the time stamp and stored in the memory 206. On the other hand, in FIG. 1, level fluctuations and quality degradation of optical signals detected by the optical receivers 106-1 to 106-n are sent to the monitoring signal transfer path 113 via the monitoring signal transfer unit 107 as monitoring signals. Sent. Further, the monitoring signal is received by the monitoring control unit 205 of the optical amplifiers 102 to 105 via the monitoring signal transfer path 113. The monitoring control unit 205 controls detection information (storage) in the memory 206 based on the monitoring signal. The detection information stored at that time is controlled to be maintained / discarded. Further, the accumulated detection information is analyzed by being transmitted to the outside, for example.

  Note that when the detection information stored in the memory is transmitted to the outside, there is a possibility that the transmission processing performance of the network may be restricted. This is because if a large amount of detection information is transmitted at a time, the monitoring network may become unstable. In order to avoid this, the memory 206 may be composed of two types of memories, a primary memory and a secondary memory. The detection information is temporarily stored in the secondary memory from the primary memory. The detection information stored in the secondary memory can be extracted from the outside (operation terminal or the like) at an arbitrary time. Specifically, the primary memory always stores detection information for a fixed time. Based on the received monitoring signal, the primary memory moves the accumulated detection information to the secondary memory. On the other hand, the secondary memory can collectively receive the detection information from the primary memory and read it out from the outside.

  Next, the optical transmission quality monitoring method in the first embodiment of the present invention will be described with reference to the time chart shown in FIG. In the optical transmission system, an optical signal being transmitted may cause a level fluctuation as shown by a power waveform 501 in FIG. 5 due to disturbance to the optical fiber transmission path or failure of the optical amplifier. The power waveform 501 in FIG. 5 is detected by the light level detectors 202 and 203 in the optical amplifier. Alternatively, the power waveform 501 is detected by the state detection unit 204 that detects a state change of the optical amplification unit. Specifically, in FIG. 2, when a level variation occurs in the optical fiber transmission line or the like before the optical level detection unit 202, the level variation is detected after the optical level detection unit 202. Further, when a level variation occurs after the light level detection unit 202 and before the light level detection unit 203, the level variation is detected after the light level detection unit 203. Further, when a level fluctuation occurs in an optical fiber transmission line or the like subsequent to the optical level detection unit 203, the level fluctuation is detected after the optical level detection unit 202 installed in the next optical amplifier. As shown in FIG. 5, these detection intervals are set to a detection interval Ts that is sufficiently shorter than level fluctuations (due to disturbances to the optical fiber transmission line, optical amplifier failures, etc.) that occur instantaneously in the optical transmission system. Yes. Therefore, the power waveform 501 is monitored at each of the monitoring points 502. The power waveform 501 is sampled and monitored at the detection interval Ts. The detection interval Ts is set to be shorter than the order of 1 msec to 100 msec, which is a level fluctuation time that occurs instantaneously in the optical transmission system. The value is, for example, from the order of 1 μsec to about 1 msec.

  When level fluctuation as shown by the power fluctuation waveform 503 in FIG. 5 occurs, the signal quality after transmission may be deteriorated. As shown in FIGS. 1 and 4, the signal quality is detected by an optical level detection unit 403 or a signal quality detection unit 404 installed in the optical receivers 106-1 to 106-n. These signal qualities are shown as a transmission quality waveform 505 in FIG. The “L” level indicates a good quality state. The “H” level indicates a quality deterioration state. The transmission quality waveform 505 is transmitted to each of the optical amplifiers 102 to 105 by the monitoring signal transfer unit 107.

  In the transmission quality waveform 505, the trigger that changes from the “L” level to the “H” level depends on the quality degradation of the received optical signal. Specific types of triggers include the following. (1) Received signal disconnection (detected by the optical level detection unit 403 in FIG. 4): When the level of the optical signal decreases and reaches a level at which the signal cannot be received, etc. (2) Frame synchronization of the received signal Misalignment (detected by the signal quality detection unit 404 in FIG. 4): When frame synchronization information based on Synchronous Digital Hierarchy, 8B10B code or 64B / 66B code of the Ethernet (registered trademark) signal cannot be identified And (3) Bit error of the received signal (detected by the signal quality detection unit 404 in FIG. 4): Bit Interleaved Parity information of Synchronous Digital Hierarchy, 8B10B code or 64B / 66B code of Ethernet signal, etc. based on For example, if it detects a No. rule violation.

  Here, the detection information detected by the optical level detectors 202 and 203 and the optical amplifier state detector 204 shown in FIG. 2 is sent to the monitoring controller 205 together with a time stamp. Then, the detection information is stored in the memory 206. As described above, the detection interval is set to a detection interval Ts that is sufficiently shorter than the level fluctuation instantaneously occurring in the optical transmission system. The memory 206 has a capacity capable of accumulating the detected information amount for a time longer than the time obtained by adding the time α and the time β described below. The time α is from the time when the level related to a certain optical signal is detected by the optical level detectors 202 and 203 of the optical amplifiers 102 to 105 and stored in the memory 206 via the monitoring controller 205. This is the time from when the optical signal is transmitted until the transmission quality related to the same optical signal is detected by the optical level detection unit 403 and the signal quality detection unit 404 of the optical receivers 106-1 to 106-n. The time β is the monitoring control unit for the optical signal from the time when the optical level detection unit 403 detects the level fluctuation or the transmission quality is detected by the signal quality detection unit 404, and the transmission quality information is used as a monitoring signal (quality degradation information). 405 and the monitoring signal transfer unit 107 are transferred to the monitoring control unit 205 installed in each of the optical amplifiers 102 to 105, and the time until the monitoring control unit 205 controls the memory 206. That is, in each optical amplifier, the information from the level fluctuation information of a certain optical signal is stored, and the quality degradation information caused by the same optical signal is detected and transferred by the optical receiver, and is controlled The memory 206 stores the detected information. The memory 206 has a capacity capable of storing the amount of information detected in the above time.

  The memory 206 has a capacity capable of accumulating the total amount of data detected at the detection interval Ts during the time τ in FIG. In other words, in the memory 206, new information is always accumulated at the detection interval Ts, while previously accumulated information is discarded from the oldest. In the memory 206, the amount of information for time τ is always accumulated.

  Therefore, when level fluctuation or quality degradation is detected by the optical level detection unit 403 or the signal quality detection unit 404 installed in the optical receivers 106-1 to 106-n, the quality degradation information is stored in the monitoring control unit. The data is transferred as a monitoring signal to the monitoring control unit 205 installed in each of the optical amplifiers 102 to 105 via 405 and the monitoring signal transfer unit 107. The monitoring control unit 205 causes the memory 206 to output the level fluctuation information accumulated retroactively to the time τ after receiving the monitoring signal. As a result, the level fluctuation information of the light level detection units 202 and 203 and the state detection unit 204 of the light amplification unit stored in the memory 206 is output, and the failure location and the failure cause are specified. Specifically, when a level fluctuation is confirmed after the optical level detection unit 202, a failure has occurred in the preceding optical fiber transmission line. By examining the specific section, the cause of failure such as disconnection can be specified. In addition, when a level change is confirmed by the state detection unit 204 of the optical amplification unit, a failure has occurred in the optical amplification unit. By examining the specific section, it is possible to specify the cause of failure such as an output abnormality of the excitation light source. Further, when level fluctuation is confirmed after the light level detection unit 203, a failure has occurred between the light level detection unit 202 and the light level detection unit 203. By examining the specific section, the cause of failure such as disconnection can be specified.

  In other words, when quality degradation is detected in the optical receivers 106-1 to 106-n at time point B in FIG. 5, the quality degradation waveform 505 becomes “H” level at time point B. . Then, a monitoring signal (quality degradation information) is transferred from the optical receiver to each optical amplifier. In the memory 206 installed in each optical amplifier, the power storage waveform 504 (black circle in the figure detected at the detection interval Ts) from the point B to the point A that is back by the time τ is displayed together with the time stamp. It is remembered. Based on this detection information, a level fluctuation such as a power fluctuation waveform 503 that causes quality degradation is specified. Further, the failure location is confirmed by the monitoring control unit 205 installed in each optical amplifier. The monitoring control unit 205 identifies in which section the failure has occurred by checking the fluctuations of the light level detection units 202 and 203 and the state detection unit 204.

  As described above, it is preferable that the detection interval Ts be sufficiently shorter than the level fluctuation that occurs instantaneously in the optical transmission system. As a result, the level fluctuation that is the cause of the failure can be reliably captured. The storage time τ is preferably set sufficiently longer than the time obtained by adding the time α and the time β so that the power fluctuation waveform 503 that is the cause of the failure can be reliably stored. As a result, the level fluctuation that is the cause of the failure can be reliably captured. Note that the memory 206 only has to have a capacity capable of accumulating detection information detected at the detection interval Ts during the storage time τ. Therefore, even if the detection interval is made shorter than before, the required memory capacity can be reduced.

  Further, the monitoring control unit 205 controls the memory 206 to hold the level variation information stored at that time without discarding based on the monitoring signal. Further, the monitoring control unit 205 may control not to transfer new level variation information from the light level detection units 202 and 203 and the state detection unit 204 of the light amplification unit to the memory 206 based on the monitoring signal.

  Furthermore, the power storage waveform 504 (black circle in FIG. 5) stored in the memory 206 of each of the optical amplifiers 102 to 105 may be able to be read according to an external request. Thereby, the administrator can perform detailed examination from the optical terminal station or the like.

  As described above, in the optical transmission system according to the first embodiment of the present invention, the level fluctuation waveform is not missed by sampling at a detection interval shorter than the conventional one. In addition, regarding the storage amount of the memory, if the storage amount is as much as the amount detected during the time τ, the information related to the failure can be stored without leaving. Therefore, it is possible to identify the cause of failure and the location of failure from the level fluctuation waveform detected in detail.

  The configuration of the optical transmission system according to the second embodiment of the present invention is shown in FIG.

  In FIG. 6, this optical transmission system includes optical transmitters 601-1 to 601-n, optical amplifiers 602 to 605, optical receivers 606-1 to 606-n, a supervisory signal transfer unit 607, A wavelength multiplexer 608, a wavelength divider 609, supervisory signal interface units 610 to 613, an operation terminal 614, optical fiber transmission lines 615 to 617, and a supervisory signal transfer path 618 are configured. Reference numerals 621 and 622 denote optical terminals.

  Next, the operation of the optical transmission system according to the second embodiment of the present invention will be described with reference to FIG. This second embodiment is the same as the first embodiment until the level fluctuation waveform due to the disturbance to the optical fiber or the failure of the apparatus is stored in the memory of each of the optical amplifiers 602-605. In addition, in this embodiment, the level fluctuation waveform stored in the memory is transmitted to the operation terminal 614 autonomously or in response to a request from the operation terminal 614 via the monitoring signal interface units 610 to 613. . The level fluctuation waveform is analyzed by the operation terminal 614.

  As described above, the optical transmission system according to the second embodiment of the present invention further includes the operation terminal 614 and the monitoring signal interface units 610 to 613. As a result, the level fluctuation waveforms stored in the memories of the optical amplifiers 602 to 605 can be easily managed, and information can be easily extracted to the outside.

    The configuration of the optical transmission system according to the third embodiment of the present invention is shown in FIG.

  In the first embodiment of the present invention, as shown in FIG. 1, a supervisory signal transfer path 113 is used as means for notifying supervisory signals (quality degradation information) from the supervisory signal transfer unit 107 to the optical amplifiers 102-105. ing. The configuration of the optical transmission system of the third embodiment is an example using other means.

  FIG. 7 shows an opposed optical transmission system, which includes optical transmitters 701-1 to 701-n, optical amplifiers 702 to 705, optical receivers 706-1 to 706-n, and monitoring signal transfer as examples of optical repeaters. Unit 707, wavelength multiplexer 708, wavelength divider 709, optical fiber transmission lines 710 to 712, optical transmitters 751-1 to 751-n, optical amplifiers 752 to 755 as an example of an optical repeater, and optical receiver 756-1 756-n, wavelength multiplexer 758, wavelength divider 759, optical fiber transmission lines 760-762, and monitoring wavelength signal transfer units 771-774. Reference numerals 781, 782 denote optical terminals, and 791, 792 denote optical repeaters.

  Next, the operation of the optical transmission system according to the third embodiment of the present invention will be described with reference to FIG. The transmission of the optical signal is the same as in the first embodiment. The optical signals transmitted from the optical transmitters 701-1 to 701-n of the optical terminal 781 are received by the optical receivers 706-1 to 706-n of the optical terminal 782. On the other hand, on the opposite side, optical signals transmitted from the optical transmitters 751-1 to 751-n of the optical terminal station 782 are received by the optical receivers 756-1 to 756-n of the optical terminal station 781. The optical receivers 706-1 to 706-n detect quality degradation of the optical signals transmitted from the optical transmitters 701-1 to 701-n. The monitoring signal (quality degradation information) is transferred to the monitoring wavelength signal transfer unit 774 via the monitoring signal transfer unit 707. Here, the monitoring signal is converted into an optical signal having a wavelength set for the monitoring signal, and is output to the optical amplifier 752 on the opposite line side installed in the same optical terminal station 782. The optical signal for monitoring is wavelength-multiplexed with the main signal light in the optical amplifier 752. Note that the wavelength of the monitoring optical signal is set to be different from the wavelength output from the optical transmitters 751-1 to 751-n. Next, this monitoring optical signal is transmitted to the optical amplifier 753 via the optical fiber transmission line 762. Here, only the monitoring signal wavelength is separated, and the monitoring optical signal is output to the monitoring wavelength signal transfer unit 773. Next, this monitoring optical signal is sent from the monitoring wavelength signal transfer unit 773 to the optical amplifier 704 as monitoring information. The monitoring optical signal may be appropriately converted from an optical signal to an electric signal and transmitted while being transmitted from the optical amplifier 753 to the optical amplifier 704. In addition, the monitoring wavelength signal transfer unit 773 returns the monitoring signal transferred as the monitoring optical signal to the optical amplifier 753 again, similarly to the monitoring wavelength signal transfer unit 774. Then, the monitoring signal is wavelength-multiplexed with the main signal light and transmitted to the next optical amplifier 754. Thereafter, the same operation is repeated.

  Thus, in the third embodiment of the present invention, the opposite line is used to transfer the monitoring signal. The monitoring signal is transferred to all the optical amplifiers by this opposite line. Therefore, in the optical transmission system according to the third embodiment of the present invention, efficient transmission of monitoring information is possible by effectively using the opposite line. The monitoring method is the same as in the first embodiment of FIG.

  The configuration of the optical transmission system according to the fourth embodiment of the present invention is shown in FIG.

  In FIG. 8, 801-1 to 801-n are optical transmission units, 802 is a wavelength multiplexing unit, 803 to 805 are optical amplifiers, 806 is a wavelength division unit, 807 is a wavelength multiplexing unit, 808 to 810 are optical amplifiers, and 811 is Wavelength division unit, 812-1 to 812-n are optical reception units, 83-1 to 813-n are optical transmission units, 814 is a wavelength multiplexing unit, 815 to 816 are optical amplifiers, 817 is a wavelength division unit, and 818 is a wavelength. Multiplexers, 819 to 820 are optical amplifiers, 821 is a wavelength division unit, 822-1 to 822-n are optical receivers, 823 is a matrix optical switch, and 824 is a supervisory signal transfer unit.

  FIG. 8 shows an application example in which an optical cross-connect function is further added to the optical transmission system of the first embodiment of FIG. The monitoring signal (quality degradation information) detected at the receiving end is transferred to the route through which the corresponding signal has passed, and the level fluctuation waveform of the optical amplifying unit, matrix optical switch, etc. is detected at each point. As in FIG. 1, the optical signals transmitted from the optical transmitters 801-1 to 801-n are wavelength-multiplexed by the wavelength multiplexer 802 and the intensity attenuated by the transmission loss by the optical amplifiers 803-805. Are sequentially returned and transmitted to the wavelength division unit 806. Next, the optical signals divided into single wavelengths by the wavelength division unit 806 are transmitted by the matrix optical switch 823 with their paths switched. FIG. 8 illustrates an example in which the optical signal transmitted from the optical transmission unit 801-1 is switched to the lower path. This optical signal is wavelength-multiplexed again with an optical signal of another wavelength by the wavelength multiplexing unit 818, and the intensity attenuated by the transmission loss is sequentially returned by the optical amplifiers 819 to 820, and the wavelength division unit 821 is returned. Sent to. Next, the optical signal divided into a single wavelength by the wavelength division unit 821 is received by the optical receiver 822-1. The optical signal received by the optical receiver 822-1 is detected as a monitoring signal, and the information is transferred to each optical amplifier via the monitoring signal transfer unit 824.

  As described above, in the third embodiment of the present invention, by adding the optical cross-connect function, it becomes possible to easily identify a failure location or the like even in an optical transmission system constructed in a mesh shape.

  Since the present invention is effective in a scene where an optical amplifier is applied, it can be applied not only to a long distance optical transmission system but also to a metro optical transmission system. In particular, in metro optical transmission systems, optical devices (optical amplifiers, optical repeaters, etc.) and optical fibers may be placed in the user's home, and there are more accidents such as increased loss due to bending of optical fibers. There are concerns that arise. Therefore, the technology of the present invention that makes it possible to easily identify a failure location is useful for all optical transmission systems regardless of long-distance optical transmission systems and metro optical transmission systems.

It is a block diagram which shows the 1st Example of this invention. It is a block diagram which shows the inside of the optical amplifier in the 1st Example of this invention. It is a block diagram which shows the inside of the optical transmitter in the 1st Example of this invention. It is a block diagram which shows the inside of the optical receiver in the 1st Example of this invention. It is a figure which shows the time chart in the 1st Example of this invention. It is a block diagram which shows the 2nd Example of this invention. It is a block diagram which shows the 3rd Example of this invention. It is a block diagram which shows the 4th Example of this invention. It is a block diagram which shows the conventional optical amplification repeater transmission system. It is a figure which shows the time chart at the time of failure occurrence in the conventional optical amplification repeater transmission system.

Explanation of symbols

101-1 to 101-n Optical transmitters 102 to 105 Optical amplifiers 106-1 to 106-n Optical receivers 107 Monitoring signal transfer unit 108 Wavelength multiplexer 109 Wavelength dividers 110 to 112 Optical fiber transmission path 113 Monitoring signal transfer path 121, 122 Optical terminal station 201 Optical amplification unit 202, 203 Optical level detection unit 204 Optical amplification unit state detection unit 205 Monitoring control unit 206 Memory 301, 401 O / E conversion unit 302, 402 E / O conversion unit 403 Optical level Detection unit 404 Signal quality detection unit 405 Monitoring control unit 501 Power waveform 502 Monitoring point 503 Power fluctuation waveform 504 Power storage waveform 505 Transmission quality waveform

Claims (49)

In an optical transmission system in which an optical repeater and an optical receiver are connected to an optical fiber transmission line,
Comprising a transfer means for transferring a monitoring signal based on quality degradation of the optical signal detected by the optical receiver from the optical receiver to the optical repeater;
The optical repeater device is:
An optical level fluctuation detection unit for detecting an optical signal level fluctuation;
A level fluctuation storage unit for storing the information of the level fluctuation,
The optical receiver is
A quality degradation detection unit that detects optical signal quality degradation,
The level variation storage unit
While storing the information on the level fluctuation at regular intervals, the information on the level fluctuation after a predetermined period is sequentially discarded, and since the information on the level fluctuation of the specific optical signal is stored,
The monitoring signal based on the quality deterioration of the specific optical signal is transferred by the transfer means, and the storage of the level fluctuation information is held until the level fluctuation storage unit is controlled. Transmission system. The optical transmission system according to claim 1, wherein the transfer unit includes a monitoring signal transfer path for transferring the monitoring signal from the optical receiver to the optical repeater. The optical transmission system according to claim 2, wherein the transfer unit further includes a monitoring signal transfer unit that sends the monitoring signal to the monitoring signal transfer path. In optical transmission systems,
One or more optical repeaters that relay optical signals;
An optical fiber transmission line for transmitting the optical signal;
An optical receiver for receiving the optical signal;
A monitoring signal transfer path for transferring a monitoring signal based on the optical signal received by the optical receiver to the optical repeater;
The optical repeater device is:
A light level fluctuation detecting unit for detecting a level fluctuation of the optical signal;
A first monitoring control unit that monitors the level variation and transmits the level variation information;
A level fluctuation storage unit for storing the level fluctuation information,
The optical receiver is
A quality degradation detector for detecting quality degradation of the optical signal transmitted through the optical fiber transmission line;
A second monitoring control unit that monitors the quality degradation and transmits it as a monitoring signal;
A monitoring signal transfer unit that transfers the monitoring signal from the second monitoring control unit to the first monitoring control unit via the monitoring signal transfer path;
The first monitoring control unit controls storage of the level fluctuation storage unit based on the received monitoring signal,
The level variation storage unit
While storing the level fluctuation information at regular intervals, the level fluctuation information that has passed a predetermined period is sequentially discarded, and the level fluctuation information of the specific optical signal is stored in the specific optical signal. An optical transmission system, wherein the level variation information is stored until a time point controlled by the first monitoring control unit by a monitoring signal based thereon. Based on the monitoring signal received from the monitoring signal transfer path, the first monitoring control unit holds the level variation information stored in the level variation storage unit at that time without being discarded. 5. The optical transmission system according to claim 4, wherein the optical transmission system is controlled. 6. The optical transmission system according to claim 1, wherein the predetermined interval is shorter than a time during which a level fluctuation causing quality degradation occurs in the optical transmission system. 7. The optical transmission system according to claim 6, wherein the fixed interval is from the order of 1 μsec to about 1 msec. The storage period of the level fluctuation information in the level fluctuation storage unit is related to a specific optical signal.
The time from when the level variation is detected by the light level variation detection unit and the level variation storage unit stores the level variation information until the quality degradation is detected by the quality degradation detection unit,
A time period from when the quality deterioration is detected by the quality deterioration detection unit to when the monitoring signal is transferred through the monitoring signal transfer path and the storage of the level variation storage unit is controlled by the first monitoring control unit; 8. The optical transmission system according to claim 4, wherein the optical transmission system is longer than the combined time. The storage capacity of the level variation information in the level variation storage unit is related to a specific optical signal.
The time from when the level variation is detected by the light level variation detection unit and the level variation storage unit stores the level variation information until the quality degradation is detected by the quality degradation detection unit,
The time from when the quality deterioration is detected by the quality deterioration detection unit to when the monitoring signal is transferred through the monitoring signal transfer path and the storage of the level variation storage unit is controlled by the first monitoring control unit. The optical transmission system according to any one of claims 4 to 7, wherein the optical transmission system is larger than a total amount of data of detected level fluctuations within the combined time. The first monitoring control unit performs control so as not to transfer new level variation information from the light level variation detection unit to the level variation storage unit based on the monitoring signal received from the monitoring signal transfer path. An optical transmission system according to any one of claims 4 to 9. The quality degradation detection unit
An optical level detector for detecting the level of the optical signal;
The optical transmission system according to claim 1, further comprising a signal quality detection unit that detects the quality of the optical signal. The optical transmission system according to claim 1, wherein the signal quality detection unit detects a reception signal loss, a frame synchronization of the reception signal, or a bit error of the reception signal. . The optical transmission system according to claim 1, wherein the level fluctuation storage unit can read the level fluctuation information from the outside. 14. The optical transmission system according to claim 1, wherein the level fluctuation storage unit is a memory. A primary memory for storing the level variation information for a predetermined time;
The optical transmission system according to claim 14, further comprising: a secondary memory that transfers and stores the level variation information from the primary memory when controlled by the first monitoring control unit according to the monitoring signal. The optical transmission system according to claim 1, wherein the optical level fluctuation detection unit is an optical receiver. The optical transmission system according to claim 1, wherein the optical repeater further includes an optical amplifying unit. The optical transmission system according to claim 17, wherein the optical repeater further includes a state detection unit that detects a state of the optical amplification unit. Similar to the level variation information, the first monitoring control unit monitors the state information of the optical amplification unit from the state detection unit, and the level variation storage unit stores the state information of the optical amplification unit. The optical transmission system according to claim 18, wherein: 20. The optical transmission system according to claim 1, wherein wavelength division multiplexing transmission is performed in the optical transmission system. 21. The optical transmission system according to claim 20, wherein the quality deterioration detection unit is provided for each individual wavelength. The optical transmission system according to claim 21, further comprising a wavelength divider that divides the wavelength multiplexed optical signal into optical signals of individual wavelengths and inputs the optical signals to each of the quality deterioration detection units. The optical transmission system according to any one of claims 1 to 22, further comprising an optical transmitter. The optical transmission system according to claim 23, wherein the optical transmitter is provided for each individual wavelength. 25. The optical transmission system according to claim 24, further comprising a wavelength multiplexer that multiplexes optical signals of individual wavelengths output from the optical transmitter. The optical transmission system according to any one of claims 1 to 19, further comprising an operation terminal that monitors the optical repeater. 27. The optical transmission system according to claim 26, further comprising an interface unit that connects the operation terminal and the optical repeater. 28. The optical transmission system according to claim 1, wherein a counter line is used as the monitoring signal transfer path. 29. The optical transmission system according to claim 28, further comprising a monitoring wavelength signal transfer unit that transmits a monitoring signal to the opposite line. 30. The optical transmission system according to claim 1, further comprising an optical cross-connect function. The optical transmission system according to claim 30, further comprising a matrix optical switch for switching a transmission path. In an optical repeater connected to an optical fiber transmission line,
An optical level fluctuation detection unit for detecting an optical signal level fluctuation;
A level fluctuation storage unit for storing the information of the level fluctuation,
The level fluctuation storage unit sequentially discards the level fluctuation information after a predetermined period while storing the level fluctuation information at regular intervals, based on a monitoring signal received from the outside, An optical repeater characterized in that the level variation information stored at that time is retained without being discarded. In an optical repeater connected to an optical fiber transmission line,
An optical level fluctuation detection unit for detecting an optical signal level fluctuation;
A monitoring control unit that monitors the level fluctuation and transmits it as level fluctuation information;
A level fluctuation storage unit for storing the level fluctuation information;
The level fluctuation storage unit sequentially discards the level fluctuation information that has passed a predetermined period while storing the level fluctuation information at regular intervals.
When the monitoring control unit receives a monitoring signal from the outside, the monitoring control unit controls the level variation information stored in the level variation storage unit at that time to be retained without being discarded. . 34. The optical repeater according to claim 32 or 33, wherein the fixed interval is shorter than a time during which a level fluctuation that causes quality degradation occurs in the optical transmission system. 35. The optical repeater according to claim 34, wherein the predetermined interval is from the order of 1 [mu] sec to about 1 msec. The monitoring control unit performs control so as not to transfer new level variation information from the light level variation detection unit to the level variation storage unit based on the monitoring signal received from the outside. 36. The optical repeater according to claim 35. 37. The optical repeater according to claim 32, wherein the level fluctuation storage unit can read the level fluctuation information from the outside. 38. The optical repeater according to claim 32, wherein the level fluctuation storage unit is a memory. The memory includes a primary memory that stores the level variation information for a certain period of time, and a secondary memory that moves the level variation information from the primary memory and stores the level variation information when controlled by the monitoring control unit using the monitoring signal. The optical repeater according to claim 38. 40. The optical repeater according to any one of claims 32 to 39, wherein the optical level fluctuation detector is an optical receiver. 41. The optical repeater according to claim 32, further comprising an optical amplifying unit. 42. The optical repeater according to claim 41, further comprising a state detection unit that detects a state of the optical amplification unit. Similarly to the level variation information, the monitoring control unit monitors the status information of the optical amplification unit from the status detection unit, and the level variation storage unit stores the status information of the optical amplification unit. 43. The optical repeater according to claim 42, wherein: 44. The optical repeater according to any one of claims 32 to 43, further comprising an operation terminal that monitors the optical repeater. 45. The optical repeater according to claim 44, further comprising an interface unit for connecting the operation terminal and the optical repeater. In a quality monitoring method for an optical transmission system in which an optical repeater and an optical receiver are connected to an optical fiber transmission line,
An optical level fluctuation detecting step for detecting an optical signal level fluctuation;
A level fluctuation storing step for storing information of the level fluctuation;
A quality degradation detection step for detecting quality degradation of the optical signal transmitted through the optical repeater and the optical fiber transmission line;
A monitoring signal transfer step of transferring a monitoring signal based on quality degradation of the optical signal to the level fluctuation storage step,
The level variation storing step sequentially discards the level variation information that has passed a predetermined period while storing the level variation information at regular intervals, and stores the level variation information of a specific optical signal. A quality monitoring method for an optical transmission system, wherein the storage of the information on the level fluctuation is held from the time point to the time point controlled by the monitoring signal based on the specific optical signal. In the quality monitoring method of the optical transmission system in which the optical repeater is connected to the optical fiber transmission line,
An optical level fluctuation detecting step for detecting an optical signal level fluctuation;
A first monitoring step of monitoring the level fluctuation and transmitting it as level fluctuation information;
A level fluctuation storing step for storing the level fluctuation information;
A quality degradation detection step for detecting quality degradation of the optical signal transmitted through the optical repeater and the optical fiber transmission line;
A second monitoring step of monitoring the quality degradation and transmitting as a monitoring signal;
A monitoring signal transfer step for transferring the monitoring signal from the second monitoring step to the first monitoring step;
The first monitoring step includes:
Based on the received monitoring signal, control the storage of the level fluctuation storage step,
The level variation storing step includes
While the level fluctuation information is stored at regular intervals, the level fluctuation information that has passed a predetermined period is sequentially discarded, and the level fluctuation information of the specific optical signal is stored, and then the specific optical signal is stored. A quality monitoring method for an optical transmission system, wherein the storage of the level variation information is held until a time point controlled in the first monitoring step by a monitoring signal based thereon. The first monitoring step is controlled based on the monitoring signal received from the monitoring signal transfer step so as to hold the level variation information stored in the level variation storage step at that time without being discarded. 48. The quality monitoring method for an optical transmission system according to claim 47, wherein: In the first monitoring step, based on the monitoring signal received from the monitoring signal transfer step, control is performed so as not to transfer new level variation information from the light level variation detection step to the level variation storage step. 49. A quality monitoring method for an optical transmission system according to claim 47 or 48, wherein

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