JPH0616608B2 - Optical link failure detection system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical link failure detection system for monitoring and controlling a moving device such as a flying object using one optical fiber.

(Prior Art) Conventionally, the technology in such a field is described in "Future Vision I of the Optoelectronic Industry" (Showa 56-3), Opto-Industrial Technology Promotion Association, P.132-133. was there. The configuration will be described below with reference to the drawings.

FIG. 2 is a block diagram showing a configuration example of a conventional bidirectional optical transmission system for a mobile body.

In this bidirectional optical transmission system, a fixed device 10 and a moving device 20 such as a flying object are connected by an optical fiber 30.
The optical fiber reel 21 incorporated therein allows the optical fiber 30 to move while being paid out. Here, the fixing device 10 includes an electro-optical conversion unit 11 that converts an electric signal S1 for control into an optical signal of wavelength λ1, an opto-electric conversion unit 12 that converts an optical signal of wavelength λ2 into an electric signal S4, and a wavelength of An optical multiplexer / demultiplexer 13 that multiplexes or demultiplexes λ1 and wavelength λ2 is provided. Further, the moving device 20 includes an optical fiber reel 21 and
Optical multiplexer / demultiplexer 22 for multiplexing or demultiplexing wavelengths λ1 and λ2
And an opto-electric converter 23 for converting an optical signal of wavelength λ1 into an electric signal S2, and an electro-optical converter 24 for converting an electric signal S3 for monitoring into an optical signal of wavelength λ2.

Next, the operation will be described.

When the control electrical signal S1 is transmitted from the fixed device 10 to the mobile device 20, the control electrical signal S1 is converted into an optical signal of wavelength λ1 by the electro-optical converter 11, and the optical multiplexer / demultiplexer 13 and the optical fiber 3 are used.
0, the optical fiber reel 21 of the moving device 20, and the optical multiplexer / demultiplexer 2
The signal is converted into an electric signal S2 by the photoelectric conversion unit 23 via 2. On the other hand, when transmitting the monitoring electric signal S3 from the mobile device 20 to the fixed device 10, the monitoring electric signal S3 is converted into an optical signal of wavelength λ2 by the electro-optical conversion unit 24, and the optical multiplexer / demultiplexer 2
2, optical fiber reel 21, optical fiber 30, and fixing device 1
The optical signal S is transmitted through the optical-electrical converter 12 via the optical multiplexer / demultiplexer 13 of 0.
Converted to 4.

(Problems to be Solved by the Invention) However, in the device having the above configuration, when detecting a failure of the bidirectional optical transmission system for a mobile object, a control electric signal is used.
A method of superimposing a sub-signal on S1, separating the sub-signal from the electric signal S2 on the mobile device 20 side, re-superimposing the sub-signal on electric signal S3 and sending back to the fixed device 10 side as a sub-signal of the electric signal S4. However, there is a problem that the failure point cannot be specified when the electric signal S3 does not reach the fixing device 10 side due to the following failure reason.

The reasons for the failure include disconnection of the optical fiber 30, disconnection of the optical fiber reel 21, failure of the optical multiplexers / demultiplexers 13 and 22, failure of the electro-optical exchanger 24, failure of the opto-electrical converter 12, and light on the mobile device 20 side. It is conceivable that there is a failure in the power supply for supplying power to the electric conversion unit 23, the electro-optical conversion unit 24, and the like.

SUMMARY OF THE INVENTION The present invention provides an optical link failure detection system that solves the problem that the prior art has in the previous term that it cannot specify a failure point, in particular, the failure of an optical fiber system and an electrical system.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a fixing device having a first optical multiplexer / demultiplexer and one optical fiber in the first optical multiplexer / demultiplexer. In a bidirectional optical transmission system between a device having a second optical multiplexer / demultiplexer connected via the optical fiber and moving while feeding the optical fiber, a monitoring light having a wavelength different from that used in the bidirectional optical transmission system Additional first and second input / output ports for the first and second optical multiplexer / demultiplexers, respectively, and a backscattered light measuring system using the monitoring light is provided on the first optical multiplexer / demultiplexer side. An optical circuit unit connected to a first input / output port and having an optical delay unit having a length detectable by the backscattered light measurement system is connected to a second input / output port on the second optical multiplexer / demultiplexer side. It was done.

(Operation) According to the present invention, since the optical link failure detection system is configured as described above, the backscattered light measurement system inserts the measurement signal into the bidirectional optical transmission system through the first optical multiplexer / demultiplexer. Then, the signal returned from the optical circuit unit is input via the second optical multiplexer / demultiplexer, and the state of the optical transmission system is monitored as the power distribution of the backscattered light. Thereby, the failure point of the optical transmission system can be specified. Therefore, the above problems can be eliminated.

(Embodiment) FIG. 1 is a configuration block diagram of an optical link failure detection system in a bidirectional optical transmission system showing an embodiment of the present invention.

In this bidirectional optical transmission system, a fixed device 40 and a moving device 50 such as a flying object are connected by one optical fiber 60 as in the conventional case, and the moving device 50 has an optical fiber reel 51 incorporated therein. By this, the optical fiber 60 can be moved while being extended.

Here, the fixing device 40 has an electro-optical conversion unit 41 for converting the control electric signal S1 into an optical signal of wavelength λ1 and an opto-electric conversion unit 42 for converting the optical signal of wavelength λ2 into an electric signal S4. , The electro-optical conversion unit 41 and the opto-electric conversion unit 42 are the optical multiplexer / demultiplexer 43
It is connected to the optical fiber 60 via. Optical multiplexer / demultiplexer 43
Then, as in the conventional case, the electro-optical conversion unit 41 and the opto-electric conversion unit 42.
In addition to the input / output ports 43a and 43b for connection with and, a first input / output port 43c for monitoring light having a wavelength λ3 is added. The optical multiplexer / demultiplexer 43 has a function of multiplexing or demultiplexing the optical signals of wavelengths λ1, λ2, λ3 through the input / output ports 43a, 43b, 43c, and the electro-optical converter 41
The optical-electrical converter 42 constitutes a part of the bidirectional optical transmission system.

A backscattered light measurement system 44 is connected to the monitoring light input / output port 43c of the optical multiplexer / demultiplexer 43. This backscattered light measurement system
Reference numeral 44 denotes a control / monitoring unit 45 having a function of outputting the electric pulse signal S5 and measuring the power distribution of the backscattered light based on the returned electric pulse signal S6, and the pulse signal S5 having a wavelength λ3. And an electro-optical conversion unit 47 for converting the returned optical pulse signal of wavelength λ3 into an electric pulse signal S6,
The optical pulse signal of wavelength λ3 is sent to the monitoring light input / output port 43c via the ports 48a and 48b, and the optical pulse signal of wavelength λ3 from the input / output port 43c is output to the ports 48b and 48c.
And a directional coupler 48 that supplies the light to the photoelectric converter 47 via the.

Further, the moving device 50 is provided with an optical fiber reel 51, and the optical fiber reel 51 has an optical input / output port 52a, 52b and an optical input / output port 52c for monitoring light which is additionally provided. The demultiplexer 52 is connected, and the opto-electric conversion unit 53 and the electro-optical conversion unit 54 are connected to the input / output ports 52a and 52b, respectively. The opto-electric converter 53 has a function of converting an optical signal of wavelength λ1 into an electric signal S2, and the electro-optical converter 54 has a function of converting an electric signal S3 for monitoring into an optical signal of wavelength λ2. The opto-electric converter 53 and the electro-optical converter 54 together with the optical fiber reel 51 and the optical multiplexer / demultiplexer 52 form a part of the bidirectional optical transmission system. An optical delay unit having a length measurable by the backscattering measurement system 44, for example, a dummy fiber 55 is connected to the monitoring light input / output port 52c of the optical multiplexer / demultiplexer 52, and the terminal portion for light reflection is further provided. The mirror 56 is connected. The mirror 56 constitutes an optical circuit unit together with the dummy fiber 55.

The operation of the optical link failure detection system configured as described above will be described with reference to FIGS. 3 (a), (b), and (c).
3A to 3C, the horizontal axis indicates the propagation time (distance).
Shows an example of the measurement of the power distribution of the backscattered light in FIG. 1 when the received power is taken on the vertical axis. In the figure (a), when the optical transmission system is normal, the figure (b) shows When the optical fiber is cut in the middle, FIG. 6C is a diagram when the optical fiber is cut in a substantially extended state.

Electric signal S1 for controlling the moving body supplied from the fixing device 40 side
Is converted into an optical signal of wavelength λ1 by the electro-optical converter 41, and is converted into an optical-electrical converter via the optical multiplexer / demultiplexer 43, the optical fiber 60, the optical fiber reel 51 on the moving device 50 side, and the optical multiplexer / demultiplexer 52. Part 53
Is converted into an electric signal S2.

The electric signal S3 for monitoring supplied from the mobile device 50 side is converted into an optical signal of wavelength λ2 by the electro-optical converter 54, and the optical multiplexer / demultiplexer is used.
52, optical fiber reel 51, optical fiber 60, and fixing device
It is converted into an electric signal S4 by the photoelectric conversion unit 42 via the optical multiplexer / demultiplexer 43 on the 40 side.

In the backscattered light measurement system 44, the pulse signal S5 output from the control monitoring unit 45 is converted into an optical pulse signal of wavelength λ3 by the electro-optical conversion unit 46, and the ports 48a and 48 of the directional coupler 48 are converted.
b, the optical multiplexer / demultiplexer 43, the optical fiber 60, the optical fiber reel 51 of the moving device 50, the optical multiplexer / demultiplexer 52, and the dummy fiber 55 to reach the mirror 56. If the optical transmission system is normal,
The optical signal of wavelength λ3 emitted from the dummy fiber 55 is
It is reflected by the mirror 56, and the reflected light is again reflected by the dummy fiber 5
5, the optical multiplexer / demultiplexer 52, the optical fiber reel 51, and the optical fiber 60 to return to the fixing device 40 side, and the optical multiplexer / demultiplexer 43 and the ports 48b and 48c of the directional coupler 48 are used for optoelectricity. The pulse signal S6 is converted by the converter 47. Then, the control and monitoring unit
In 45, the power distribution of the backscattered light as shown in FIG. 3 (a) can be measured based on the pulse signal S6. That is, when the optical transmission system is normal, the pulse waveform 80 of the reflected light from the optical multiplexer / demultiplexer 52 and the like, and the pulse waveform 81 of the reflected light from the mirror 56 delayed by the delay of the dummy fiber 55 from that.
And is obtained.

When the optical fiber 60 is cut in the middle, it is shown in Fig. 3 (b).
As shown in, the waveform is erased at the cutting point 82 of the optical fiber 60, so that the control monitoring unit 45 can detect that the optical fiber 60 has been cut halfway.

The optical fibers 60 are all extended from the optical fiber reels 51 and are connected to the moving device 50, that is, the optical fiber reels 51.
When the moving device 50 is broken at the connection point between the optical multiplexer / demultiplexer 52 and the optical multiplexer / demultiplexer 52, or when the moving device 50 is broken while the optical fiber 60 is almost extended, as shown in FIG. Since the waveform is erased at the full length cut point 83 of the fiber 60 and the pulse waveform of the reflected light by the mirror 56 does not appear, it is possible to detect the state where the connection point with the moving device 50 is broken or the moving device 50 is broken. From these things, it can be said that the purpose of the dummy fiber 55 is provided to accurately detect the state of the optical transmission system when the optical fiber 60 is almost drawn out.

As described above, in this embodiment, the backscattered light measurement system 44 is provided on the fixed device 40 side, and the dummy fiber 55 and the mirror 56 for reflecting the optical pulse for measurement are provided on the moving device 50 side. In the measurement system 44, the state of the optical transmission system can be monitored as the power distribution of the backscattered light. Therefore, when used in combination with the electrical failure detection method described in the prior art, the failure point can be identified with certainty.

The present invention is not limited to the illustrated embodiment, and various modifications can be made. The following are examples of such modifications.

(I) The optical delay section may use, for example, an optical delay line or the like utilizing the reflection of the multifaceted glass block, instead of the dummy fiber 55.

(Ii) The mirror 56 may have another structure, for example, a structure in which a metal film or the like is directly deposited on the end portion of the dummy fiber 55. Further, even if these mirror functions are removed and, for example, a measurement optical pulse is supplied from the terminal end portion of the dummy fiber 55 and transmitted to the fixing device 40 side, substantially the same effect as the above embodiment can be obtained. .

(Effect of the invention) As described in detail above, according to the present invention, since the backscattered light measurement system is provided on the fixed device side and the optical circuit unit is provided on the moving device side, the The state of the transmission system can be monitored as the power distribution of the backscattered light, whereby the failure point in the optical transmission system can be specified accurately.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical link failure detection system in a bidirectional optical transmission system showing an embodiment of the present invention, FIG. 2 is a configuration block diagram of a conventional bidirectional optical transmission system, FIG. 3 (a),
(b), (c) is a figure which shows the measurement example of the electric power distribution of the backscattered light in FIG. 40 …… Fixing device, 41,46,54 …… Electro-optical converter, 42,4
7,53 …… Optical-electric converter, 43,52 …… Optical multiplexer / demultiplexer, 44…
… Backscattered light measurement system, 45 …… Control and monitoring unit, 48 …… Directional coupler, 50 …… Movement device, 51 …… Optical fiber reel, 55
…… Dummy fiber, 56 …… Mirror, 60 …… Optical fiber.

Claims (4)

[Claims] 1. A fixing device having a first optical multiplexer / demultiplexer, and a second optical multiplexer / demultiplexer connected to the first optical multiplexer / demultiplexer via one optical fiber. In a bidirectional optical transmission system with a moving device that moves while feeding out a fiber, first and second input / output ports for supervisory light having different wavelengths used in the bidirectional optical transmission system are provided as the first and second The backscattered light measuring system is installed in each of the second optical multiplexer / demultiplexers, and the backscattered light measuring system using the monitoring light is connected to the first input / output port on the side of the first optical multiplexer / demultiplexer. 2. An optical link failure detection system characterized in that an optical circuit section having an optical delay section of a length detectable by 1. is connected to the second input / output port on the side of the second optical multiplexer / demultiplexer. 2. The optical link fault detection system according to claim 1, wherein the optical circuit section is composed of the optical delay section and a mirror for reflecting light connected to a terminal portion of the optical delay section. 3. The optical link fault detection system according to claim 1 or 2, wherein the optical delay section is formed of a dummy fiber. 4. The optical link fault detection system according to claim 1 or 2, wherein the optical delay section is composed of an optical delay line utilizing reflection of a multifaceted glass block.