JP2002261706A - Optical transmission system provided with obstacle detection function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission system capable of transmitting transmission data without being broken even when an obstacle occurred in an optical transmission path for connecting between end offices. SOLUTION: In a transmitter 2, a modulation circuit 5 modulates data to be transmitted in a given modulation system. A diagnosis signal output from a diagnosis signal generator 6 is overlapped on the modulated transmission data, and the overlapping signal is converted into an optical signal by an E/O conversion circuit 7. The optical signal is transmitted to a receiver 3 via an optical transmission path 4, and is converted into an electric signal by an O/E conversion circuit 8 of the receiver 3. Next, this electrical signal is discriminated into the transmission data and the diagnosis signal by a discriminator 9, and a diagnosis circuit 11 diagnoses according to the diagnosis signal whether an obstacle generates in the optical transmission path 4. Thus, the obstacle generated in the optical transmission path can be detected with high precision and instantaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission system for performing optical transmission through an optical transmission line, and more particularly, to a technique for notifying an operator of a failure in the optical transmission line when the failure occurs. About.

[0002]

2. Description of the Related Art For example, as a communication network for transmitting various data used in automobiles, railcars, aircraft, houses, and the like, ring-type, daisy-chain, and other networked optical transmission systems are used. I have.

In an optical transmission system, an optical transmission path is provided between a plurality of terminal stations, an electric signal to be transmitted is converted into an optical signal by a terminal station on the transmitting side, and the optical signal is transmitted through the optical transmission path. And transmits it to the terminal station on the receiving side. The receiving-side terminal station can obtain desired data by converting the received optical signal into an electric signal.

In such an optical transmission system, when a failure such as disconnection occurs in the optical transmission line, data transmission between the terminal stations becomes impossible. Therefore, even in such a case, in order to enable data transmission without hindrance, for example, Japanese Patent Application Laid-Open No. Hei 7-135483
An optical transmission system as described in the related art) has been proposed.

FIG. 6 is a block diagram showing a configuration of an optical transmission system described in the conventional example. As shown in FIG. 1, the optical transmission system 101 includes two optical transmission devices 10.
2 and 103, and the optical transmission devices 102 and 10
3 is connected via two optical transmission lines 104 and 105.

[0006] The optical transmission apparatus 102 includes a line switching circuit 1
10, two optical transmission circuits 111 and 112, and two optical demultiplexing / combining devices (hereinafter referred to as WDM) 113 and 114.
, A light receiving circuit 115, and a control circuit 116. The optical transmission circuit 111 converts the transmission data into an optical signal of a first wavelength, and the optical transmission circuit 112 converts the transmission data into an optical signal of a second wavelength.

Similarly, the line switching circuit 120 and the two optical transmission circuits 12
1, 122, two WDMs 123 and 124, an optical receiving circuit 125, and a control circuit 126.

When data is transmitted from the optical transmission device 102 to the optical transmission device 103, first, the line switching circuit 110 is switched to the optical transmission circuit 111.
Then, the data to be transmitted is converted into an optical signal (optical signal of the first wavelength) by the optical transmission circuit 111, and the WDM 1
13 port P1. This optical signal is transmitted to the WDM of the optical transmission apparatus 103 via the optical transmission path 104.
The signal is output to the optical receiving circuit 125.

At this time, since the optical transmission circuit 112 is not operating, the signal output from the WDM 124 is only the optical signal of the first wavelength provided through the optical transmission line 104.

When a failure occurs in the optical transmission line 104 and the optical transmission line 104 is disconnected, the optical receiving circuit 1
25, no optical signal is input. When this is detected, the line switching circuit 110 performs a switching operation to select the optical transmission circuit 112. As a result, the data to be transmitted is converted into an optical signal of the second wavelength by the optical transmission circuit 112 and output to the WDM 123 on the optical transmission apparatus 103 side via the WDM 114 and the optical transmission path 105.

Thereafter, the optical signal (optical signal of the second wavelength) output from the WDM 123 is supplied to the optical receiving circuit 125 via the WDM 124. Thereby, even when the optical transmission line 104 is disconnected, the optical transmission line 105
Can be used to transmit data.

[0012]

However, the optical transmission system 101 described in the above-mentioned conventional example has the following problems.

(1) Since a line switching circuit 110 operates after a failure such as a disconnection has occurred in one of the optical transmission lines to switch the optical transmission path to the other optical transmission line,
When a failure occurs in the optical transmission path, an instantaneous interruption occurs in the optical transmission. Therefore, data transmission is temporarily impaired.

(2) The optical transmission device that receives the optical signal compares the intensity of the received optical signal with a preset threshold value, and when the optical signal intensity falls below the threshold value, It is configured to detect that the transmission line is disconnected.
Therefore, we have not seen the change in the intensity of the received optical signal,
It is not possible to determine when a failure will occur. In other words, since the configuration is such that a failure is detected after a failure has occurred, the failure cannot be prevented from occurring.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to prevent instantaneous interruption even when a failure such as disconnection occurs in an optical transmission line. It is an object of the present invention to provide an optical transmission system having a failure detection function capable of preventing a failure and predicting a failure occurrence time.

[0016]

According to a first aspect of the present invention, an optical transmission line is provided between a plurality of terminal stations and an optical transmission line provided between the terminal stations. In an optical transmission system having a function of diagnosing a failure that occurs in a terminal station on the transmitting side, a diagnostic signal is superimposed on transmission data at an arbitrary timing, and the terminal station on the receiving side transmits the transmission data on And detecting the diagnostic signal, and detecting occurrence of a failure in the optical transmission line based on the diagnostic signal.

According to a second aspect of the present invention, there is provided an optical transmission system having a function of performing optical transmission between a plurality of terminal stations and diagnosing a fault occurring in an optical transmission line provided between the terminal stations. In the terminal station on the transmitting side, modulating means for modulating the transmission data, diagnostic signal generating means for outputting a diagnostic signal for diagnosing the occurrence of a failure, transmission data modulated by the modulating means, An electrical signal / optical signal converting means for superimposing the diagnostic signal and converting the superimposed signal into an optical signal, wherein the terminal station on the receiving side converts the received optical signal into an electric signal. Optical signal / electrical signal converting means, separating means for separating the electric signal into the transmission data and the diagnostic signal, and detecting occurrence of a fault in the transmission path based on the separated diagnostic signal. Failure diagnosis means. And wherein the door.

According to a third aspect of the present invention, the diagnostic signal is a DC voltage signal, and the fault diagnosing means determines a level of a fault occurring in the optical transmission line according to a level of the DC voltage signal. It is characterized by making a judgment.

According to a fourth aspect of the present invention, the diagnostic signal is superimposed on the transmission data at predetermined time intervals.

According to a fifth aspect of the present invention, the optical transmission system is used for data transmission in a vehicle, and the diagnostic signal is superimposed on the transmission data in synchronization with the ignition of the vehicle. It is characterized by the following.

According to a sixth aspect of the present invention, when a terminal station which may cause a failure in the optical transmission line is confirmed based on the diagnostic signal, this information is notified to each terminal station. It is characterized by.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a first embodiment of an optical transmission system to which the present invention has been applied. As shown in FIG. 1, the optical transmission system 1 includes a transmitting device 2 and a receiving device 3. Then, the transmitting device 2 converts the data to be transmitted into an optical signal, and transmits the optical signal to the receiving device 3 via the optical transmission line 4. In addition, the receiving device 3 can obtain desired data by converting the light transmitted from the transmitting device 2 into an electric signal.

The transmitting apparatus 2 periodically or irregularly transmits a modulation circuit 5 for modulating data to be transmitted by a predetermined modulation method and a diagnostic signal for diagnosing whether a failure has occurred in the optical transmission line 4. A diagnostic signal output from the diagnostic signal generator 6 is superimposed on the data (electric signal) modulated by the diagnostic signal generator 6 and the modulation circuit 5 periodically, and this superimposed signal is converted into an optical signal (for example, a wavelength of 650 nm). ), And an electric signal / optical signal conversion circuit (hereinafter, referred to as “E / O conversion circuit”) 7.

The receiving device 3 includes an optical signal / electrical signal conversion circuit (hereinafter referred to as an “O / E conversion circuit”) 8 for converting the optical signal transmitted from the transmission device 2 into an electric signal, and the O / E conversion circuit. A classifier 9 for classifying an electric signal output from the circuit 8 into transmission data and a diagnostic signal, a demodulation circuit 10 for demodulating the transmission data separated by the classifier 9 to obtain desired data, A diagnostic circuit 11 for reading the diagnostic signal sorted by the sorter 9 and diagnosing whether a failure has occurred in the optical transmission line 4.

FIG. 2 is a block diagram showing a detailed configuration of the diagnostic circuit 11. As shown in FIG.
Three reference voltage signals V1, V2, V3 (V1> V
2> V3), the reference voltage generator 21 and the classifier 9
The diagnostic signal Vs given by the reference voltages V1 and V
2, a comparator 22 having comparators 31, 32, and 33 for comparing V3 and V3, and comparators 31, 32, and 33.
Status signal S based on the comparison result data
1, S2, S3, and S4, and an encoding unit 24 that generates encoded data based on the status signals S1, S2, S3, and S4.

Next, the operation of the optical transmission system 1 according to the first embodiment configured as described above will be described.
When transmitting data from the transmitting device 2 to the receiving device 3,
First, data to be communicated is supplied to the modulation circuit 5.

The modulation circuit 5 modulates the supplied data by a predetermined modulation method (frequency modulation, amplitude modulation, etc.).
As a result, for example, a rectangular pulse signal S1 as shown in FIG. 3A is obtained.

On the other hand, when a signal (for example, a DC voltage signal) for diagnosing the optical transmission line 4 is output from the diagnostic signal generator 6, the E / O conversion circuit 7 first outputs the signal from the modulation circuit 5. A signal (rectangular pulse signal S1) and a diagnostic signal (DC voltage ΔV) are superimposed. As a result, as shown in FIG. 3B, a signal is obtained in which the DC voltage of ΔV is superimposed on the rectangular pulse signal S1. Then
This signal (electric signal) is converted into an optical signal.

Thereafter, this optical signal is transmitted to the receiving device 3 via the optical transmission line 4 and supplied to the O / E conversion circuit 8 of the receiving device 3. The O / E conversion circuit 8 performs a process of converting an optical signal into an electric signal. Next, the electric signal is supplied to the classifier 9, and a process of classifying the transmission data and the diagnostic signal is performed. That is, the rectangular wave pulse signal S1 and the superimposed signal of the DC voltage shown in FIG. 3B are separated from each other, and the rectangular wave pulse signal S1 (see FIG. 3A) is output to the demodulation circuit 10, while , DC voltage to diagnostic circuit 11
Output to The DC voltage at this time is defined as a diagnostic signal Vs (a signal changed by the DC voltage ΔV passing through the optical transmission line 4).

The demodulation circuit 10 demodulates the supplied rectangular wave pulse signal S1 to extract data to be transmitted, and outputs the data to a subsequent processing system (not shown).

The diagnostic signal Vs given to the diagnostic circuit 11 is applied to each of the comparators 31,
32, 33, and further, each of the comparators 31, 3
2, 33 are supplied with voltage signals V1, V2, V3 (V1>V2> V3) output from the reference voltage generator 21. Therefore, the output signal O1 of the comparator 31 becomes a signal (“H” or “L” digital signal) indicating the result of comparison between the diagnostic signal Vs and the voltage signal V1, and the output signal O2 of the comparator 32 becomes the diagnostic signal Vs The signal indicates the result of comparison with the voltage signal V2,
The output signal O3 of No. 3 is a signal indicating the result of comparison between the diagnostic signal Vs and the voltage signal V3.

The output signals O1, O2, O2
O3 is supplied to the logic unit 23, converted into four status signals S1 to S4, and encoded by the encoding unit 24.

In this processing, for example, the diagnosis signal Vs
When V3> Vs, (S1, S2, S3, S
4) is (0,0,0,1), (0,0,1,0) when V2>Vs> V3, (0,1,0,0), Vs when V1>Vs> V2 When> V1,
Status signals S1 to S4 that are (1, 0, 0, 0,)
Is output. That is, when the optical transmission line 4 is functioning normally, the diagnostic signal Vs is set to be larger than the voltage signal V1, and the status signals S1 to S4
Becomes (1, 0, 0, 0). Then, as the scale of the fault occurring in the optical transmission line 4 increases, the status signal S
1 to S4 are (0, 1, 0, 0), (0, 0, 1,
0), (0, 0, 0, 1).

The status signals S1 to S4
Is output to a subsequent processing step (not shown) as diagnostic data. Thus, when a decrease in the level of the diagnostic signal Vs is detected, for example, adjustment such as increasing the optical output in the E / O conversion circuit 7 can be performed.

In this manner, the diagnostic signal (voltage ΔV) output from the transmitting device 2 is received by the receiving device 3 and the signal level of the received diagnostic signal Vs is detected, whereby the diagnostic data of the optical transmission line 4 is converted. You can get it.

As described above, in the optical transmission system 1 according to the present embodiment, the transmission signal transmitted from the transmission device 2 to the reception device 3 is periodically (eg, every one minute) or irregularly (for the vehicle). In the case of (1), the diagnostic signal is superimposed at the time of starting the engine and the like, and this signal is transmitted to the receiving device 3 via the optical transmission line 4. The receiving device 3 separates the received signal into a transmission signal and a diagnostic signal, and diagnoses a failure occurrence state in the optical transmission path based on the level of the diagnostic signal obtained as a result of the classification.

Therefore, when a failure such as a disconnection occurs in the optical transmission line 4, it can be immediately detected and notified to the operator by an alarm signal or the like. The diagnostic signal V
By detecting the decrease in the level of s, it is possible to recognize this before the optical transmission line 4 is disconnected and the signal transmission is completely cut off. Therefore, it is possible to avoid a trouble that a signal cannot be transmitted.

Next, a second embodiment of the present invention will be described. FIG. 4 is a block diagram illustrating a configuration of the optical transmission system according to the second embodiment. As shown in the figure, this optical transmission system 41 has three terminal stations T1, T2, T3.
Are connected by optical transmission lines L12, L23, and L31, and data is transmitted between the terminal stations T1 to T3.

The terminal station T1 includes a modulation circuit 42-1 for modulating data to be transmitted by a predetermined modulation method, and an optical transmission line L12.
Diagnostic signal generator 43 for periodically or irregularly outputting a diagnostic signal for diagnosing whether a failure has occurred in the
-1 and data (electric signal) modulated by the modulation circuit 42-1
The diagnostic signal output from the diagnostic signal generator 43-1 is superimposed on the optical signal (for example, a wavelength of 650 nm).
Electrical / optical signal conversion circuit (hereinafter referred to as “E / O
A conversion circuit) 44-1).

Further, an optical signal / electric signal conversion circuit (hereinafter, referred to as an “optical signal / electric signal”) for converting the optical signal transmitted from the terminal station T3 into an electric signal.
An O / E conversion circuit) 45-1, a classifier 46-1 for classifying an electric signal output from the O / E conversion circuit 45-1 into transmission data and a diagnostic signal, and a classifier 46-1 A demodulation circuit 47-1 that demodulates the transmission data classified by 46-1 to obtain desired data and a diagnostic signal that is classified by the classifier 46-1 are read, and a failure occurs in the optical transmission line L31. And a diagnosis circuit 48-1 for diagnosing whether or not the operation is performed.

The terminal stations T2 and T3 are also
Since it has the same configuration as that of No. 1, each component is given a suffix "-2" or "-3", and the description of the configuration is omitted.

Next, the operation of the optical transmission system 41 configured as described above will be described. Terminal station T1 to terminal station T
2, data to be transmitted is modulated by the modulation circuit 42-1 and transmitted from the diagnostic signal generator 43-1 as in the first embodiment. The diagnostic signal (voltage ΔV shown in FIG. 3B) is periodically (eg, every one minute) or irregular (in the case of a vehicle,
(E.g., when the engine is started).
It is converted into an optical signal in 4-1.

This optical signal is transmitted to the terminal station T2 via the optical transmission line L12. Then, the terminal station T2 converts the optical signal transmitted by the O / E conversion circuit 45-2 into an electric signal,
Further, the classifier 46-2 performs a process of classifying the data to be transmitted and the diagnostic signal.

The diagnostic circuit 48-2 has a configuration similar to that shown in FIG. 2, and outputs status signals S1 to S4 corresponding to the level of the diagnostic signal Vs from the diagnostic circuit 48-2. . Thus, the operator of the terminal station T2 can be notified that a failure has occurred in the optical transmission line L12.

In this case, a failure may occur in the terminal station T2. That is, although data is transmitted from the terminal station T1 to the terminal station T2, there is a possibility that this data is not transmitted to the terminal station T2. Therefore, a signal (diagnosis data) indicating that a failure may occur in the terminal station T2.
Is transmitted to the other terminal stations T1 and T3.

FIG. 5 is an explanatory view showing transmission data to which diagnostic data has been added. N frames (N is the number of terminal stations and N = 3 in this embodiment) are provided before the transmission data. The writing area R1 is set. Then, the diagnostic circuit 48
In step -2, a process of writing data (code D1) indicating that a failure has occurred in a portion corresponding to the terminal station T2 in the data write area R1. Then, this data is transmitted to the terminal station T3 via the optical transmission line L23. Similarly, this data is transmitted to the terminal station T1 via the optical transmission line L31.

Thus, the operators of the terminal station T3 and the terminal station T1 can recognize that a failure may occur in the terminal station T2. In this way, when a failure occurs in the optical transmission lines L12, L23, L31 connecting the terminal stations T1 to T3, the failure is immediately detected, and the terminal station which may cause a transmission failure may be detected. Can be notified to the terminal station and other terminal stations.

As described above, in the optical transmission system 41 according to the present embodiment, when performing data transmission between the plurality of terminal stations T1 to T3, the optical transmission line L12 connecting the terminal stations T1 to T3 is used. , L23 and L31 can be detected immediately, so that the failure can be dealt with early. Also, data indicating that a failure has occurred
Since the signals are transmitted to the terminal stations T1 to T3, the terminal stations T1 to T3
Can quickly recognize the occurrence of a failure.

Although the optical transmission system of the present invention has been described based on the illustrated embodiment, the present invention is not limited to this, and each component may have any configuration having the same function. Can be replaced by

For example, in the first and second embodiments,
Although the signal output from the diagnostic signal generator is a DC voltage signal (ΔV shown in FIG. 3B), the present invention is not limited to this, and other signals can be used.

Further, in the second embodiment, an example having three terminal stations T1 to T3 has been described. However, the present invention is not limited to this, and may be applied to a case where four or more terminal stations are provided. , A similar technique can be used.

[0052]

As described above, in the optical transmission system according to the present invention, when transmitting transmission data from a terminal station on the transmission side to a terminal station on the reception side, the transmission-side terminal station transmits the data. The diagnostic signal is superimposed on the transmission data. Then, the receiving terminal detects this diagnostic signal and diagnoses whether a failure has occurred in the optical transmission line connecting the two terminals.
Therefore, the occurrence of a failure can be detected with high accuracy and immediately.

Since the degree of the failure can be recognized based on the level of the diagnostic signal, it is possible to cope with the occurrence of the failure before the transmission of the transmission data is interrupted.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an optical transmission system according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a detailed configuration of a diagnostic circuit.

FIG. 3 (a) is a signal to be transmitted, and FIG. 3 (b) is (a)
FIG. 4 is an explanatory diagram showing a signal obtained by superimposing a diagnostic signal on the signal shown in FIG.

FIG. 4 is a block diagram illustrating a configuration of an optical transmission system according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing transmission data added with data for notifying a terminal station where a failure may occur.

FIG. 6 is a block diagram showing a configuration of a conventional optical transmission system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical transmission system 2 Transmitting device 3 Receiving device 4 Optical transmission line 5 Modulation circuit 6 Diagnostic signal generator 7 Electric signal / optical signal conversion circuit (E / O conversion circuit) 8 Optical signal / electric signal conversion circuit (O / E conversion) Circuit) 9 Classifier 10 Demodulation circuit 11 Diagnostic circuit 21 Reference voltage generation unit 22 Comparison unit 23 Logical operation unit 24 Encoding unit 31, 32, 33 Comparator 41 Optical transmission system T1 to T3 terminal station L12, L23, L31 Optical transmission path 42-1 to 42-3 Modulation circuit 43-1 to 43-3 Diagnostic signal generator 44-1 to 44-3 E / O conversion circuit 45-1 to 45-3 O / E conversion circuit 46-1 to 46- 3 Classifier 47-1 to 47-3 Demodulation circuit 48-1 to 48-3 Diagnostic circuit

Claims (6)

[Claims] 1. An optical transmission system for transmitting light between a plurality of terminal stations and having a function of diagnosing a fault occurring in an optical transmission line provided between the terminal stations. The station superimposes a diagnostic signal on the transmission data at an arbitrary timing, and the terminal station on the receiving side receives the transmission data and detects the diagnostic signal, and based on the diagnostic signal, An optical transmission system having a failure detection function for detecting occurrence of a failure in a transmission path. 2. An optical transmission system having a function of performing optical transmission between a plurality of terminal stations and diagnosing a fault occurring in an optical transmission line provided between the terminal stations. The station modulates the transmission data, a diagnostic signal generator that outputs a diagnostic signal for diagnosing the occurrence of a failure, and superimposes the transmission data and the diagnostic signal modulated by the modulator, And an electric signal / optical signal converting means for converting the superimposed signal into an optical signal, wherein the terminal station on the receiving side converts the received optical signal into an electric signal. A classification unit that classifies the electrical signal into the transmission data and the diagnostic signal; and a failure diagnosis unit that detects occurrence of a failure in the transmission path based on the classified diagnostic signal. Obstacles characterized by An optical transmission system provided with the detection function. 3. The diagnostic signal is a DC voltage signal,
The optical transmission system according to claim 2, wherein the failure diagnosis unit determines a level of a failure occurring in the optical transmission line according to a level of the DC voltage signal. 4. The optical transmission system according to claim 1, wherein the diagnostic signal is superimposed on the transmission data at a predetermined time interval. system. 5. The optical transmission system is used for data transmission in a vehicle, and the diagnostic signal is superimposed on the transmission data in synchronization with turning on of an ignition of the vehicle. Any one of claims 1 to 3
An optical transmission system provided with the failure detection function according to the paragraph. 6. The terminal according to claim 1, wherein when a terminal in which a failure may occur is confirmed in the optical transmission line based on the diagnostic signal, this information is notified to each terminal. An optical transmission system comprising the failure detection function according to claim 5.