JPH08304230A - Method for diagnosing optical transmission line - Google Patents

Abstract

PURPOSE: To accurately diagnose the light damping amount of an optical cable in a short time by transmitting a plurality of diagnosis signals which can be distinguished from each other and are emitted at different intensities from a transmitting side and identifying what degree of intensity in the signals can be received on the receiving side. CONSTITUTION: Intensity-adjusted diagnosis signals are transmitted to a transmission station 12 from a transmission station 11. When the station 12 receives the diagnosis signals, namely, when a photoelectric conversion section 17 D/A- converts the diagnosis signals, the diagnosing section 13 of the station 12 reads the intensity level of the received diagnosis signals from the signal number information of the diagnosis signals contained in the diagnosis signals. After the section 13 reads the intensity level, a response signal to the station 11 is generated by means of a diagnosed data preparing section 14 and sent to the station 11 after the signal is A/D-converted by means of an electrooptical conversion section 16. The photoelectric conversion section 17 of the station 11 D/A- converts the response signal and inputs the converted signal to the diagnosing section 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing an optical transmission line in an optical multiplex transmission system, and more particularly to a method for diagnosing an optical transmission line suitable for being applied to a system in a radiation controlled area.

[0002]

2. Description of the Related Art In a current nuclear power plant or the like, an optical multiplex transmission system as shown in FIG. 14 is used in order to reduce the cable length between a large number of field boards and control boards.

In this optical multiplex transmission system, a transmission side transmission station (transmission station) 1 has a diagnostic section 2, an electric → optical conversion section 3 and an optical → electrical conversion section 4, and is almost the same as the transmission side transmission station 1. same configuration of the plurality of receiving-side transmission station (receiving station) 5 (5 ₁ ...
5 _N ) are connected via an optical transmission cable (optical fiber cable) 6 and a star coupler 7.

With the configuration of this optical multiplex transmission system, a plurality of signals from each field device are collectively transmitted to the control panel by the multiplex transmission field panel, and the grouped signals from the control panel are multiplexed. The transmission site panel enables branch transmission to each field device.

By the way, since an enormous amount of data is transmitted to the optical multiplex transmission line for measuring and controlling the plant,
When a transmission line abnormality occurs, the influence of this abnormality on the plant operation is very large. Therefore, in order to avoid the transmission path abnormality as much as possible, the state check (optical attenuation rate measurement) of the optical transmission cable is performed not only at the time of constructing the plant but also at the periodic inspection of the plant.

A conventional optical cable optical attenuation factor measuring method will be described with reference to FIGS.

The measurement of the optical attenuation factor of the optical transmission cable 6 is shown in FIG.
As shown in FIG. 16 and FIG. 16, the optical power meter 9 is used to measure the transmitted light intensity and the received light intensity, and the optical transmission cable 6
It is performed by calculating the optical attenuation factor of. First, FIG.
As shown in FIG. 5, in order to measure the optical attenuation rate of the optical transmission cable 6, the transmitting station 1 is set to the continuous light emission state, and the optical transmission cable 6 is detached from the transmitting station 1, and the light emitting element (electricity → optical conversion unit) The intensity of transmitted light is measured by directly inputting the light intensity of the optical signal emitted from 3) to a measuring device called an optical power meter 9.

Next, as shown in FIG. 16, the optical transmission cable 6 is connected to the transmitting station 1, the optical signal emitted from the light emitting element (electricity → optical conversion portion 3) is passed through the optical transmission cable 6, and the optical signal after passing is passed. The light intensity of the signal is measured as the received light intensity of the light receiving element (light → electric conversion unit 4), and the light attenuation rate of the optical transmission cable 6 used for the measurement is calculated. If the optical attenuation rate of several thousand optical transmission cables is to be measured, the above-mentioned measurement is individually performed for each optical transmission cable, and therefore, much labor is currently required for the optical attenuation rate measurement. Exam time is spent.

Further, there is no means for measuring the optical attenuation factor of the optical transmission cable 6 during the operation of the plant, and if the optical attenuation factor of the optical transmission cable 6 is a prescribed value (for surely transmitting the optical signal, due to some factor). Even if the value exceeds the value set in (1), there is no means to detect the abnormality of the optical transmission line until the system abnormality occurs due to the inability to transmit the optical signal, and the abnormality of the optical transmission line can be detected. could not.
Particularly in a nuclear power plant or the like, the state of the optical transmission cable may change due to the influence of radiation, and the optical attenuation rate of the optical transmission cable may increase. For this reason, optical transmission cables are required to measure the optical attenuation rate on a regular basis. However, work in the radiation controlled area is a factor that increases the radiation exposure of workers, and the optical attenuation rate of the optical transmission cable increases. It was difficult to make a measurement.

[0010]

In the case of the conventional optical transmission line diagnosis method, since the number of optical transmission cables used in the present plant is several thousand, it is attempted to measure all of these optical attenuation factors. Then, there is a problem that a lot of labor and time are required.

Further, in the optical attenuation rate measurement when connecting the optical transmission cable to the transmission station, even if the optical attenuation rate is within the allowable range for reliably transmitting the optical signal from the transmitting side to the receiving side. Depending on the plant environment, the state of the optical transmission cable may change over time and the optical attenuation rate may increase, and the optical signal that passes through the optical transmission cable may change to the light receiving element (light on the receiving side → electrical conversion element). There is a possibility that the light reception level will be reduced. There is a problem that this cannot be predicted by the conventional optical transmission path diagnosis method.

The present invention has been made in consideration of the above-mentioned circumstances, and an object thereof is to provide an optical transmission line diagnosing method capable of diagnosing the optical attenuation of an optical transmission cable extremely easily and accurately. To do.

Another object of the present invention is to provide an optical transmission line diagnostic method capable of constantly monitoring the optical attenuation of an optical transmission cable.

Another object of the present invention is to provide an optical transmission line diagnostic method capable of avoiding confusion of diagnostic signals when diagnosing the optical attenuation of a plurality of optical transmission cables.

Another object of the present invention is to provide an optical transmission line diagnostic method capable of diagnosing the optical attenuation of an optical transmission cable without disturbing the transmission of normal signals.

Still another object of the present invention is to provide an optical transmission line diagnostic method capable of temporarily suppressing troubles caused by the inability of optical signal transmission of an optical transmission cable and ensuring soundness of optical signal transmission. To provide.

Another object of the present invention is to provide an optical transmission line diagnosing method capable of detecting an abnormality of an optical transmission cable at an early stage and avoiding a trouble that an optical signal cannot be transmitted.

Another object of the present invention is to provide a method for diagnosing an optical transmission line capable of always grasping information about the optical transmission cable.

Still another object of the present invention is to provide an optical transmission line diagnosing method capable of improving the reliability of optical attenuation amount diagnosis of an optical transmission cable.

[0020]

In order to solve the above-mentioned problems, an optical transmission line diagnosing method according to the present invention, in transmitting and receiving an optical signal between devices through an optical transmission cable,
A method of diagnosing the optical attenuation of an optical transmission cable by transmitting multiple diagnostic signals that are distinguishable from each other and have different emission intensities from the transmission side, and which emission intensity of the diagnostic signals can be received by the reception side. is there.

The optical transmission line diagnosing method according to the present invention also includes
This is a method of periodically transmitting and receiving a diagnostic signal in a time zone in which there is no normal signal under the normal signal priority condition in transmitting and receiving an optical signal between devices via an optical transmission cable.

The optical transmission line diagnosing method according to the present invention also inserts a diagnostic signal into a blank portion of the time rotation of the normal signal transmission / reception when the optical signal transmission / reception is performed between a plurality of devices via the repeater. In this method, the response signal is transmitted from the receiving side after receiving the diagnostic signals from all the transmitting sides to which the optical signals are transmitted and received.

The optical transmission line diagnosing method according to the present invention further stops the transmission and reception of the diagnostic signal immediately when the transmission of the normal signal is requested during the diagnosis of the optical attenuation of the optical transmission cable, and the normal signal is transmitted. Is a method of transmitting.

The optical transmission line diagnosing method according to the present invention also diagnoses whether or not the transmission light amount of the optical signal from the transmission side is a level suitable for transmission, based on the optical attenuation amount of the optical transmission cable,
This is a method of adjusting the transmitted light amount of an optical signal according to the change of the optical attenuation amount of the optical transmission cable.

Furthermore, the present invention is a method for constantly diagnosing the optical attenuation of an optical transmission cable and predicting a temporal change of the optical attenuation based on the diagnostic data of the optical attenuation.

The optical transmission line diagnosing method according to the present invention also determines whether or not the optical attenuation is an appropriate value for transmitting all data and optical signals obtained by diagnosing the optical attenuation of the optical transmission cable. This is a method of centrally managing judgment information at one place.

The optical transmission line diagnosis method according to the present invention further comprises:
When optical signals are transmitted and received between a plurality of devices via a relay device, by comparing the optical intensity of the optical signal on the transmitting side and the optical intensity of each optical signal on the plurality of receiving sides, This is a method of diagnosing the optical attenuation of a plurality of connected optical transmission cables.

[0028]

In the optical transmission line diagnosing method according to the present invention, a plurality of diagnostic signals which are distinguishable from each other and have different emission intensities are transmitted from the transmitting side, and these are received by the receiving side. By the way, if the optical attenuation of the optical transmission cable increases, the diagnostic signal with weak emission intensity is attenuated on the way and cannot be received by the receiving side. By detecting it, it becomes possible to easily and accurately diagnose the optical attenuation of the optical transmission cable.

In the optical transmission line diagnosing method according to the present invention, the diagnostic signal is periodically sent and received under the normal signal priority condition. Therefore, it is possible to constantly monitor the optical attenuation of the optical transmission cable.

In the optical transmission line diagnosing method according to the present invention, when the optical signals are transmitted and received between the plurality of devices, the receiving side transmits the diagnostic signals from all the transmitting sides to which the optical signal is transmitted and received. After receiving, a response signal is emitted. Therefore, it is possible to diagnose the optical attenuation of multiple optical transmission cables,
Moreover, it is possible to avoid confusion of diagnostic signals.

Further, in the optical transmission path diagnosing method according to the present invention, when a request for transmitting a normal signal is generated, the transmission and reception of the diagnostic signal is immediately stopped and the normal signal is transmitted. Therefore, it is possible to diagnose the optical attenuation of the optical transmission cable without disturbing the transmission of the normal signal.

In the optical transmission path diagnosing method according to the present invention, the emitted light amount of the optical signal is adjusted according to the change of the optical attenuation amount of the optical transmission cable. For this reason, it becomes possible to temporarily suppress the trouble caused by the optical transmission failure of the optical transmission cable and to secure the soundness of the optical signal transmission.

In the optical transmission line diagnosing method according to the present invention, the temporal change of the optical attenuation amount is predicted based on the diagnostic data of the optical attenuation amount. Therefore, it becomes possible to detect the abnormality of the optical transmission cable at an early stage and avoid the trouble that the optical signal cannot be transmitted.

Further, in the optical transmission line diagnosing method according to the present invention, all the diagnostic data of the optical attenuation and the judgment information regarding the diagnosis are centrally managed at one place. For this reason,
It becomes possible to always grasp information about the optical transmission cable.

In the optical transmission line diagnosing method according to the present invention, the optical attenuation of the plurality of optical transmission cables connected between the devices is further diagnosed by comparing the optical intensities of the optical signals on the transmitting side and the receiving side. It Therefore, it is possible to improve the reliability of the optical attenuation diagnosis of the optical transmission cable.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an optical transmission line diagnosis system provided in an optical multiplex transmission system for carrying out the optical transmission line diagnosis method according to the present invention. This optical transmission line diagnostic system is a transmission station 1 that serves both as a transmitter and a receiver.
1, 12 and each transmission station 11, 12
Is a diagnostic unit 13, a diagnostic data creation unit 14, an information processing unit 1
5, an electricity-> light conversion section 16 and a light-> electricity conversion section 17 are provided respectively. Both of these transmission stations 11, 1
The light-to-electricity conversion unit 16 which is the light emitting element of No. 2 and the light-to-electricity conversion unit 17 which is the light receiving element are connected to each other by an optical transmission cable 18.

When diagnosing the optical transmission line, one of the transmission stations 11 and 12 is set to the transmitting side and the other is set to the receiving side. Then, a diagnostic signal, which is a test signal as shown in FIG. 2, is transmitted from the transmission side, for example, from the transmission station 11 to the reception side.
For example, which diagnostic level of signal level is sequentially transmitted to the transmission station 12 and which can be received by the receiving side diagnostic unit 1
The optical attenuation factor is measured by the measurement in 3.

As shown in FIG. 2, each diagnostic signal transmitted from the transmission station on the transmitting side is digitally characterized, and the light level is adjusted stepwise by the light intensity. Some of the signals have optical levels (optical brightness) exceeding level A to maintain a comfortable transmission state.
From the minimum reception level B of the receiving station
The light level (light brightness) below is included. In FIG. 2, the vertical axis represents the light emission level Y, and the horizontal axis represents the number of transmissions X.

FIG. 3 shows an operational flowchart of the optical transmission line diagnosis in the optical transmission line diagnosis system, which will be described below.

First, in step S1, a diagnostic signal of normal brightness is transmitted from the transmitting side, and at the same time, in step S1.
In 2, it is judged whether or not this diagnostic signal is received by the receiving side. If it is not received, an error is displayed in step S3, while if it is received, in step S4, a diagnostic signal having a brightness which is one level lower than the previous brightness is transmitted.

Next, in step S5, it is determined whether or not this diagnostic signal has been received by the receiving side. If not, in step S6 it is determined whether or not it is within the allowable range. If it is not within the allowable range, an error is displayed in step S7, and if it is within the allowable range, a normal display is displayed in step S8.

On the other hand, if it is determined in step S5 that the diagnostic signal has been received, it is determined in step S9 whether or not it is within the allowable range, and if it is not within the allowable range, an error is displayed in step S10. If it is within the allowable range, it is determined in step S11 whether or not the brightness level of the diagnostic signal is minimum. If it is minimum, normal display is performed in step S12. On the other hand, if it is not the minimum, the procedure returns to step S4 and the optical transmission line diagnosis procedure is repeated.

Next, the flow of the optical transmission line diagnosis system will be specifically described.

From FIG. 1, the optical brightness (optical brightness) of the diagnostic signal (for diagnosing the optical attenuation of the optical cable) transmitted from the transmission station 11 is a value around the optical intensity required for transmitting the optical signal. As a diagnostic unit 1 of the transmission station 11
3 in order to digitally characterize the diagnostic signal for each light intensity in the diagnostic data creating unit 14,
The current value flowing into the electricity-to-light conversion unit 16 is adjusted.

The electrical-to-optical conversion unit 16 converts the diagnostic signal classified by light intensity and characterized into an analog signal into a digital signal. Here, the digital characterization of the diagnostic signal is performed by "1111" for the first-stage diagnostic signal subjected to light intensity adjustment and "1110" for the second-stage diagnostic signal.
The diagnostic signal number is attached in this way.

Then, when the diagnostic signal whose light intensity is adjusted is transmitted from the transmission station 11 to the transmission station 12 and the transmission station 12 receives this diagnostic signal, that is, the diagnostic signal is converted into a digital signal by the optical-electrical conversion unit 17. When the signal is converted into an analog signal (current), the diagnostic section 13 of the transmission station 12 reads the light intensity level of the diagnostic signal from the diagnostic signal number information included in the diagnostic signal. After reading the received diagnostic signal, a response signal to the transmission station 11 is sent to the diagnostic data creation unit 1
4, the electrical-to-optical converter 16 converts the analog signal into a digital signal and transmits the response signal to the transmission station 11. The response signal is transmitted by the transmission station 1
The optical-to-electrical converter 17 converts the digital signal into an analog signal, and the optical-to-electrical converter 17 enters the diagnostic unit 13.

As shown in FIG. 3, the flow of operation of the optical transmission line diagnostic system is as follows. That is, the diagnostic unit 13 of the transmission station 11 determines the light intensity of the diagnostic signal received by the transmission station 12 based on the presence or absence of the response signal from the transmission station 12, and the transmission station 1
It is diagnosed whether the optical attenuation amount of the transmission side optical transmission cable 18 from 1 to the transmission station 12 is an appropriate value for transmitting an optical signal.

At this time, when a response signal from the transmission station 12 to the transmission station 11 exists, a diagnostic signal having a light intensity which is one level lower than the diagnostic signal obtained from the transmission station 12 is newly created, A command signal is sent from the diagnostic unit 13 to the diagnostic data creating unit 14 so as to be transmitted to the diagnostic data generating unit 12. Diagnostic data creation unit 1
4 receives this command signal, creates a diagnostic signal of the command content, and sends it to the transmission station 12. Such an operation is performed within the set optical level range of the diagnostic signal until there is no response signal or until all diagnostic signals within the set range have been transmitted.

When the optical transmission cable branched to a plurality of stations is to be diagnosed, the optical-to-electrical conversion levels of the receiving elements 17 of the plurality of receiving stations are set in advance in the diagnostic section 13 of the diagnostic signal transmitting station. Light of a plurality of light receiving elements → light composed of electrical conversion levels → the upper limit of the electrical conversion level band is used to transmit an optical signal in the diagnostic unit 13 of the diagnostic signal transmission station (when there is no optical attenuation by the optical cable). It is defined as the required minimum light intensity.

Then, the diagnostic signal, which has been subjected to light intensity adjustment and digital characterization, is sequentially transmitted from the transmitting station to the plurality of receiving stations through the optical transmission cable 18. When the receiving station receives the diagnostic signal, the number information of the diagnostic signal received from the receiving side to the transmitting side is digitally characterized as a response signal to transmit the number information of the received diagnostic signal to the transmitting side. For example, when the receiving side receives the diagnostic signal (test signal) of the number information of "1110", the response signal of the same number information of "1110" is transmitted to the transmitting side. The transmitting side can receive the response signal and determine the light intensity that can be received by each receiving station, and can check the optical attenuation of the optical transmission cable 18 connected between the transmitting and receiving stations.

In this optical transmission line diagnostic system, since only the optical transmission cable 18 on the side for transmitting an optical signal is diagnosed, the same optical transmission line diagnostic system as that of the transmission substrate is provided on the board to which the signals are connected. Thus, the optical attenuation amount diagnosis of the two optical transmission cables (optical transmission cable and optical reception cable) 18 connected between the substrates can be performed.

Next, the diagnostic method in the optical transmission line diagnostic system for diagnosing the optical attenuation of the optical transmission cables connected to the transmission stations 11 and 12 will be specifically described. Since the optical intensity of an optical signal that is normally transmitted is a value that is several tenths (or several times) higher than the minimum optical intensity required to transmit an optical signal, the optical intensity of the optical signal is N
Divided into stages (N = 10 in this embodiment),
It is assumed that the light intensity level of the optical signal in the normal time is 8.

Here, the optical attenuation factor and the received light intensity are

[Equation 1] Therefore, the diagnostic criterion is set to the received light intensity (light intensity obtained by the light receiving element of the receiving substrate). However, the “light intensity attenuated when propagating through the optical transmission cable” includes the light intensity that the light receiving element 17 cannot receive. Table 1 shows the relationship between equation (1) and the soundness of the optical transmission cable.

[0055]

[Table 1] However, 10 to 1 are the emission intensity levels, ☆ is the attenuation amount of the light intensity when the light receiving propagates through the optical transmission cable, and ○ and × are
It shows the diagnostic result of whether the receiving element received the optical signal and was able to convert light to electricity.

Referring to Table 1, in the normal state, the optical signal is received at the emission intensity level 5 and is not received at the level 4, which means that the normal optical signal propagates through the optical transmission cable 18. Considering the light intensity attenuation ☆, the light emission intensity must be at least 5 in order to propagate the optical signal.
It means that you have reached the level. When this happens when the optical attenuation rate changes, the optical signal is not transmitted at level 5, and the minimum level 6 is required to transmit the optical signal.
It is understood that the light intensity of is required.

Therefore, in order to provide a margin between the minimum light intensity required to transmit the optical signal and the actual emission intensity, somewhere in the emission intensity level of the optical signal, Set an allowable level that the amount of attenuation ☆ should not increase. Therefore, a time when an emission intensity level higher than the allowable level is required for transmitting an optical signal is defined as an abnormal time. This makes it possible to diagnose whether or not the amount of light attenuation by the optical transmission cable 18 at the time of diagnosis is an appropriate value for transmitting an optical signal (corresponding to the measurement of the optical attenuation rate).

Further, in the light intensity adjustment of the diagnostic signal (adjustment of the current value flowing into the electricity → light conversion portion 16 by the diagnosis data creation portion 14), stable electricity → light conversion is performed in consideration of the light emitting ability of the light emitting element. It should be done within the range. In addition, by inputting the light receiving level of the optical-to-electrical conversion element in advance, the optical attenuation amount of the optical transmission cable at the time of measurement is compared with the reference value with reference to the optical attenuation amount of the optical transmission cable 18 at the normal time. And how much has changed. Further, the temporal change of the optical attenuation of the optical transmission cable 18 is predicted based on the collected data for diagnosing the optical attenuation, and as shown in FIG. When it is expected that transmission is not possible), a warning is displayed by lighting an LED lamp or the like, and an error is displayed when an abnormality is diagnosed due to the large light intensity attenuated by the optical transmission cable 18.

FIG. 4 is a graph showing the actually measured values displayed as black circles, with the light emission amount P received on the vertical axis and the time T on the horizontal axis, and the tendency of the actually measured values is received after t hours. It can be seen that the minimum emitted light amount H is reached.

Simultaneously with the error display, in order to improve the quality of the optical transmission line diagnosis system, response signals are received from a plurality of receiving stations and an average value of the received light intensity is calculated. By comparing one received signal with another, it is possible to employ dual information processing for detecting anomalies such as a few optical transmission cables having an abnormally large amount of optical attenuation compared to others.

Further, in order to transmit an optical signal from the transmitting station to the receiving station in all states other than the disconnection of the optical transmission cable, the light emitting element (electricity → optical conversion) of the transmitting station is compared with the optical attenuation of the optical transmission cable. The function of diagnosing whether the emission intensity of the element is an appropriate value and automatically adjusting the emission intensity according to the change of the optical attenuation of the optical transmission cable is added. This is to avoid an emergency situation where the optical signal transmission is impossible because the optical attenuation of the optical transmission cable became larger than the allowable value due to some trouble and an abnormality occurred, but it was delayed to find this abnormality. It is effective in maintaining the optical signal transmission state as long as possible by increasing the intensity of transmitted light.

During actual operation of the control circuit, in order to make this optical transmission line diagnosis system function, as shown in FIG. 5, the time rotation of a plurality of normal signals a to m exchanged between transmission stations is performed. Diagnostic signal Z in one corner
By arranging the signals according to the light levels, the diagnostic signal Z can be made independent of the normal signals a to m.

Specifically, when optical signals are transmitted and received between a plurality of transmission stations via a relay station, a diagnostic signal, which is an optical signal transmitted from one transmission station, is transmitted and received at one time by the relay station. Since it is distributed and transmitted to the target transmission stations,
As shown in FIG. 5 (B), after the arbitrary receiving station R receives the diagnostic signals from all the transmission stations to N to which the optical signals are transmitted and received, a response signal is transmitted to each of the transmission stations to N. Thus, the optical attenuation of the optical transmission cable connected between the plurality of boards is diagnosed.

At this time, in order to avoid confusion of the diagnostic signals between the stations, the diagnostic signal and the response signal are characterized for each signal transmission / reception station. For example, if signal transmission / reception is performed between the transmission stations and N, a part of the characteristics of the diagnostic signal and the response signal for diagnosing the optical attenuation of the optical transmission cable connected between the transmission stations will be ( Create a place to put diagnostic information for each station, such as N). When each station receives the diagnostic signal and the response signal, only the information of the designated place assigned to each station is used as a target for diagnosis and information processing.

In FIGS. 6 to 11, (X) is
The side which transmitted the diagnostic signal is shown. Further, (R) indicates the side that has received the diagnostic signal.

FIGS. 6, 7, and 8 are cycles of the diagnostic signal performed in the first cycle in FIG. 5, and show the states of transmission start, transmission midway, and transmission end of the diagnostic signal, respectively.

In FIG. 6, each transmission (R) station receives and stores the diagnostic signal from the transmission (X) station.

In FIG. 7, each transmission (R) station receives and stores the diagnostic signal from the transmission (X) station.

In FIG. 8, each transmission (R) station receives and stores the diagnostic signal from the transmission (X) station ~ N.

FIGS. 9 and 10 show response signal cycles performed in the second cycle of FIG. 5, showing the state of starting transmission of the response signal, the middle of transmission, and the end of transmission, respectively.

The operations shown in FIGS. 6 to 11 are performed on one light level of the diagnostic signal.

After the operation shown in FIG. 11 is completed, the light level of the diagnostic signal is changed and the state shown in FIG. 6 is restored again.

Further, as shown in FIG. 12, the operation of the optical transmission line diagnostic system is mainly performed by exchanging the diagnostic signal between the stations, and when the necessity of the normal signal exchange occurs, the optical signal is processed in the information processing section 15. Sensing the input of normal signals a, a ', b, b', c, c'to the circuit for transmitting and receiving,
Diagnostic unit 1 sends a diagnostic stop signal to stop the exchange of diagnostic signals.
By transmitting the diagnostic signal, the transmission and reception of the diagnostic signal is stopped, and the confusion between the normal signal and the diagnostic signal is prevented.

As soon as the normal signal is not sent / received again, the information processing unit 15 senses the normal signal not sent / received, transmits a diagnosis restart signal to the diagnosis unit 13, and redos the diagnosis.

Next, an optical transmission line diagnostic system as shown in FIG. 13 is used to centrally manage all the optical transmission cables connected between the stations. The flow of this system will be described below. Each transmission station 20 ₁ , 20 ₂ ...
In the information processing unit 15, the diagnostic data from the diagnostic unit 13 is sorted by 20 _n , and the individually sorted diagnostic data is transmitted to the information processing unit 21. The information processing unit 21 organizes the transmitted diagnostic data for each optical transmission cable and for each diagnostic time, and transmits the organized diagnostic data to the management unit 27 and the storage unit 23.

The management unit 22 receives the diagnostic data (whether or not the optical attenuation of the optical transmission cable is an appropriate value for transmitting the optical signal with a margin) and the monitor 24.
By displaying the transmission status of the all-optical transmission cable in the normal and abnormal states, if there is an abnormality in some optical transmission cable, the position of the abnormal optical transmission cable can be made clear. The storage unit 23 processes the transmitted diagnostic data in various forms (such as the tendency of change in optical attenuation) and uses the required storage data depending on the situation.

By automating the same test as the optical attenuation rate measurement of the optical transmission cable which is used in many large plants such as the present nuclear power plants, the trouble due to the large optical attenuation of the optical transmission cable can be found early. At the same time, the test (optical attenuation rate measurement) time for checking the state of the optical transmission cable can be omitted.

This optical transmission line diagnostic system is not limited to the above embodiment, and the following method can be used as the method for measuring the optical attenuation factor of the optical transmission cable.

The light intensity for each level of the test signal is input to the transmission board and the reception board in advance in the optical transmission line diagnostic system.
Further, by inputting the electricity-to-light conversion rate P [dB / A] of the light-emitting element and the light-to-electricity conversion rate Q [A / dB] of the light-receiving element, the current value flowing in the circuit due to the exchange of signals between the substrates. By measuring, it is possible to indirectly measure the light emission intensity and the light reception intensity.

For example, the level 5 test current A [A] →
An optical signal of light intensity X (= Pf (A)) [dB] is transmitted from the transmission board to the reception board through the optical transmission cable,
If a current B [A] flows through the receiving substrate when the receiving substrate receives this optical signal, the received light intensity Y (= f (B) is obtained from the light-to-electrical conversion rate Q [A / dB] of the light receiving element. /
Q) I understand [dB]. Thereby, the optical attenuation factor H (= Y / X) of the optical transmission cable can be obtained. here,
In order to avoid the situation where the optical signal cannot be received from the receiving side because the optical attenuation rate H of the optical transmission cable is large and the optical attenuation rate cannot be measured, an error occurs if the optical signal is not received by the receiving board. Therefore, the optical signal having the light intensity increased by one level is transmitted again. If the optical signal is not received by the receiving substrate even if the optical intensity is one level higher, the optical intensity level is sequentially increased until the optical signal is received by the receiving substrate.

However, the upper limit of the light intensity of the test optical signal is
Since the optical attenuation rate of the optical transmission cable is too large, the optical transmission cable is considered to be unsuitable for transmitting an optical signal (at this time, a value that also takes into consideration the light emitting ability of the light emitting element). In this measuring method, as shown in FIG. 1, the receiving station side diagnoses the optical transmission cable through which the test signal propagates from the test signal transmitted from the transmitting station side. In addition, the accuracy of diagnosis is improved by inputting the temporal deterioration tendency of the light emitting element into the diagnosis unit 13 in advance in consideration of the deterioration of the light emitting element.

[0082]

As described above, according to the present invention, a plurality of diagnostic signals which are distinguishable from each other and have different emission intensities are transmitted from the transmitting side, and which emission intensity of the diagnostic signals can be received by the receiving side. Thus, the optical attenuation of the optical cable is diagnosed, so that the diagnosis can be performed easily and accurately in a short time.

According to the present invention, the diagnostic signal is periodically transmitted and received under the normal signal priority condition. Therefore, the optical attenuation amount of the optical cable is constantly monitored, and the optical attenuation amount is promptly changed. You can take action.

Further, according to the present invention, when transmitting and receiving an optical signal between a plurality of devices, a response signal is transmitted from the receiving side after receiving diagnostic signals from all transmitting sides to which the optical signal is transmitted and received. Therefore, the optical attenuation amounts of a plurality of optical cables can be diagnosed, and confusion of diagnostic signals can be avoided.

Further, according to the present invention, when a request for transmitting a normal signal is generated, the transmission and reception of the diagnostic signal is immediately stopped and the normal signal is transmitted, so that the transmission of the normal signal is not hindered. , It is possible to diagnose the optical attenuation of the optical cable.

Further, according to the present invention, the transmitted light amount of the optical signal is adjusted according to the change of the optical attenuation amount of the optical cable, so that the trouble caused by the optical signal transmission failure of the optical cable is temporarily suppressed, and the optical signal is transmitted. The soundness of signal transmission can be ensured.

Further, according to the present invention, the temporal change of the optical attenuation amount is predicted based on the diagnostic data of the optical attenuation amount. Therefore, the trouble of the optical signal transmission being impossible due to the early detection of the abnormality of the optical cable is caused. It can be prevented.

Further, according to the present invention, all the diagnostic data of the optical attenuation and the judgment information concerning the diagnosis are centrally managed at one place, so that the information concerning the optical cable can be grasped at all times.

Further, according to the present invention, the optical attenuation of a plurality of optical cables connected between devices is diagnosed by comparing the optical intensities of optical signals on the transmitting side and the receiving side. The reliability of quantity diagnosis can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of an optical transmission line diagnosis system used for implementing an optical transmission line diagnosis method according to the present invention.

FIG. 2 is an explanatory diagram showing a diagnostic signal used for optical transmission path diagnosis.

FIG. 3 is a flowchart showing the operation of the diagnostic system.

FIG. 4 is an explanatory diagram showing a method of predicting a temporal change in optical attenuation of an optical cable.

FIG. 5 is a diagram showing the positioning of the exchange of a normal signal and a diagnostic signal between transmission stations.

FIG. 6 is a diagram showing a transmission start state of a diagnostic signal in signal exchange between a plurality of stations.

FIG. 7 is a diagram showing a state in which a diagnostic signal is being transmitted during signal exchange between a plurality of stations.

FIG. 8 is a diagram showing a transmission end state of a diagnostic signal in signal transmission / reception between a plurality of stations.

FIG. 9 is a diagram showing a transmission start state of a response signal in signal exchange between a plurality of stations.

FIG. 10 is a diagram showing a state in which a response signal is being transmitted when signals are exchanged between a plurality of stations.

FIG. 11 is a diagram showing a transmission completion state of a response signal in signal transmission / reception between a plurality of stations.

FIG. 12 is an explanatory diagram showing the positioning of a diagnostic signal in signal exchange between stations.

FIG. 13 is a configuration diagram showing a system for centrally managing optical cable management and data storage.

FIG. 14 is a configuration diagram showing a conventional optical multiplex transmission device.

FIG. 15 is an explanatory diagram showing a method of measuring a light emission level in a conventional optical transmission path diagnosis method.

FIG. 16 is an explanatory diagram showing a method of measuring a light reception level in a conventional optical transmission diagnostic method.

[Explanation of symbols]

 1, 2 Transmission station 3 Diagnostic unit 4 Diagnostic data creation unit 5 Information processing unit 6 Electricity → Optical conversion unit 7 Optical → Electric conversion unit 8 Optical transmission cable X Light emission level Y Number of transmissions A A Level for maintaining a comfortable transmission state B Minimum receiving level of the sending station

Claims (8)

[Claims] 1. In transmitting and receiving an optical signal between devices via an optical transmission cable, a plurality of diagnostic signals which are distinguishable from each other and have different emission intensities are transmitted from a transmitting side, and which emission intensity of the diagnostic signals is transmitted. A method for diagnosing an optical transmission line, which comprises diagnosing an optical attenuation amount of an optical transmission cable by determining whether or not the signal can be received by a receiving side. 2. An optical signal transmission / reception between devices performed via an optical transmission cable is characterized in that a diagnostic signal is periodically transmitted / received in a time period in which there is no normal signal under normal signal priority conditions. The optical transmission line diagnosis method according to claim 1. 3. When an optical signal is transmitted and received between a plurality of devices via a relay device, a diagnostic signal is inserted in a blank portion of the time rotation of the normal signal transmission, and from the receiving side,
The response signal is transmitted after receiving the diagnostic signals from all the transmission sides of the optical signal transmission / reception target.
The optical transmission line diagnosis method described in. 4. During the diagnosis of the optical attenuation of the optical transmission cable,
2. The optical transmission line diagnostic method according to claim 1, wherein when a request for transmitting the normal signal is generated, the transmission and reception of the diagnostic signal is immediately stopped and the normal signal is transmitted. 5. Based on the amount of optical attenuation of the optical transmission cable, it is diagnosed whether the amount of emitted light of the optical signal from the transmitting side is a level suitable for transmission, and according to the change of the amount of optical attenuation of the optical transmission cable. The optical transmission line diagnosing method according to claim 1, wherein the transmitted light amount of the optical signal is adjusted. 6. The light according to claim 1, wherein the optical attenuation of the optical transmission cable is constantly diagnosed, and the temporal change of the optical attenuation is predicted based on the diagnostic data of the optical attenuation. Transmission line diagnostic method. 7. A centralized collection of judgment information as to whether or not the optical attenuation amount is an appropriate value for transmitting all data and optical signals obtained by diagnosing the optical attenuation amount of the optical transmission cable. The optical transmission line diagnosis method according to claim 1, wherein the optical transmission line diagnosis is performed. 8. When optical signals are exchanged between a plurality of devices via a relay device, the optical intensity of the optical signal at the transmitting side and the optical intensity of each optical signal at the plurality of receiving sides are compared with each other. The optical transmission line diagnosis method according to claim 1, wherein the optical attenuation amount of the plurality of optical transmission cables connected between the devices is diagnosed by the method.