JPH0677905A - Apparatus for transmission of optical signal - Google Patents

Abstract

PURPOSE: To provide a device for transmitting an optical signal in which lots of glass fibers are laid by connecting a passive distributor V equipped with a branch part halfway between one repeating place and lots of subscribers. CONSTITUTION: A distributor V is connected to a repeating place so that respective subscribers are connected to the distributor V through at least one of glass fibers 1 and 2. Branch parts K are connected to the distributor V each other by a cascade arrangement. At respective stages of the cascade arrangement, each one of the other branch part K is connected to an output terminal of the branch part K starting from the glass fiber 1 coming from the repeating place. In order to easily connect an OTDR device, a branch part equipped with a 2nd input terminal is inserted into the final stage of the cascade arrangement viewed at least in the subscriber direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention arranges a large number of glass fibers by intermediately connecting a single passive distributor equipped with a plurality of branches between a relay point and a large number of subscribers. ,
It relates to a device for transmitting optical signals, wherein the distributor is connected to a relay point and each subscriber is connected to the distributor via at least one glass fiber.

[0002]

Such devices are used, for example, in the field of local telephone networks which connect subscribers to public telecommunication systems. Through fiberglass, subscribers can receive all available narrowband and broadband services. In this case, a "subscriber" is an individual subscriber who has, for example, a telephone or telefax in his residence. But "subscriber"
May be a skyscraper or a hospital with at least one glass fiber leading from the distributor. The signal introduced via the glass fiber is distributed internally to a number of devices in such a "subscriber". Furthermore, the "subscriber" is also the point of distribution of the above signals in the usual way.

In order to control the function of such a device, an OTDR (Optical Time Domain Reflection) device is usually used. This device evaluates the backscatter signal of the laser pulse delivered into the glass fiber, from which an indication for the attenuating coating of the glass fiber is obtained. Defects in the course of glass fiber can also be positioned by the OTDR device. If the number of glass fibers connected to the distributor and reaching the subscriber is high, there is a problem in using the OTDR device. The backscatter signal is attenuated depending on the number of branches used, so that
The dynamic range of TDR devices is severely limited. Furthermore, since the backscattered signal represents the summed signal from all transmission paths, it is almost impossible to attribute possibly occurring fiber breaks to a particular glass fiber.

[0004]

SUMMARY OF THE INVENTION The object of the invention is to configure a device of the type mentioned at the outset, so that attenuation measurements and determination of faults lead to results which can be used with an OTDR device. Especially.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the above object is to provide an intermediate connection of one passive distributor having a plurality of branch portions between one relay point and a large number of subscribers.
Arranging a large number of glass fibers, the distributor is a relay point,
Also, in a device for transmitting optical signals, in which each subscriber is connected to a distributor via at least one glass fiber, one input terminal E and at least two output terminals in each of the distributors V in a cascade arrangement are provided. The branches K having A1 and A2 are connected to each other, and at each stage of the cascade arrangement,
Starting from the glass fiber coming from the relay point VST, the output end of the branch K is connected to the input end of the other branch K, respectively, and at least in the direction of the subscriber T, the last of the cascade arrangement. In the stage, it is solved by using a branch K equipped with a second input M.

Other advantageous configurations according to the invention are described in the dependent claims.

[0007]

The use of this device ensures a simple attenuation measurement and a reliable identification of the defect. By using the OTDR device first in the last stage of the cascade device, there is no significant loss to the backscatter signal. If in the preferred embodiment the final stage branch of the cascade has only two outputs, the backscatter signal is only halved. In this device, the backscattered signal is the summed signal from only a few, preferably two, transmission paths, so that the located defect can be easily attributed to the defective glass fiber. Inspection of the glass fibers connected to the branch does not disturb the simultaneous operation of other transmission lines. The OTDR device can be connected particularly easily each time. This is because the branch for this is equipped with two inputs that can be easily handled.

A branch with two inputs is advantageous only for use in the final stage of the cascade system. Because,
This is because simply connecting the OTDR device to that location will produce effective and useful results.

The terms "input end" and "output end" have been chosen for simplicity in the branch used. These terms correspond to this function when transmitting signals from the intermediary to the subscriber. In the other transmission direction, the output of the branch is the input of this branch, in which case the input is the output.

[0010]

The present invention will be described in more detail below with reference to preferred embodiments. As shown in FIG. 1, the glass fiber 1 is introduced into the passive distributor V from the relay point VST of the telecommunication network. The distance between the relay point VST and the distributor V is arbitrary within the boundaries of the system. The distributor V can also be arranged in the relay point VST. In the example shown, eight distributors T are connected to the distributor V via one glass fiber 2 each. The number of subscribers T connected to the distributor V is likewise arbitrary, again within the boundaries of the system. At least one glass fiber 2 is used for each subscriber T.
Two glass fibers, for example, are arranged between the relay point VST and the distributor V. These glass fibers are used alternately when the distributor V has two input ends.

In the distributor V, according to FIG. 2, a number of branches K are interconnected in three stages I, II and III in a cascade arrangement. Each branch K is configured as shown in FIG. 3, for example. This branch has one input and two outputs A1 and A2. The other branch K in the distributor V is connected to each output of the branch K at its input. Corresponding glass fibers in the branches are interconnected, for example by fusion splicing. These glass fibers can also be connected with a connector.

In stage I of the scade arrangement, a branch K is connected to the glass fiber 1 coming from the junction. Stage II of the scade arrangement has two branches. The inputs of these branches are connected to the two outputs of the stage I branch K. Since every branch of stage I has two outputs, four branches K are provided in stage III. The inputs of these branches are connected to one output of each stage K of stage II. From the branch K in stage III, the glass fiber 2 leads to the subscriber T. Stage I
The branch K of II has in the preferred embodiment only two outputs. Therefore, only two glass fibers 2 can be connected. If an OTDR device is connected to the branch K described above, attenuation measurements and positioning of defective parts can be performed particularly easily.

When eight or more subscribers T are connected to the relay point VST, three or more branch parts K in the distributor V can be connected in a cascade. Of course, it is also possible to use a branch having two or more outputs. The branch K of FIG. 4 with three outputs can be used each time. In stage II of the distributor V, three branches K have already been arranged, whereas in stage III, there are nine branches K. Three
Branches with more than one output can also be used. Similarly,
It is possible to connect less than eight subscribers T to one distributor V.

In the illustrated embodiment, stage K branch K
Has a second input M, as can be seen in FIG. This second input M is used to connect an OTDR device.
This can be mass-produced by plugging the input end.
This kind of second input end M can be polished obliquely to optimize the reflection. In the known technique, the second input terminal M can be extended by forming a so-called “Pigtail” (Pigtail) that connects the OTDR devices.

[0015]

As described above, the apparatus for transmitting an optical signal according to the present invention provides a result that attenuation measurement and determination of a defective portion can be used in a state where an OTDR apparatus is used.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus according to the present invention.

FIG. 2 is an enlarged view of a distributor that can be used in this device.

FIG. 3 is a diagram showing a configuration of a branch unit.

FIG. 4 is a diagram showing a configuration of another branch unit.

FIG. 5 is a diagram showing a configuration of another branch unit.

[Explanation of symbols]

 1, 2 glass fiber A1, A2 output end E input end K branch part M second input end T subscriber V distributor VST relay point

Claims (4)

[Claims] 1. A passive distributor having a plurality of branching parts is intermediately connected between one relay point and a large number of subscribers to arrange a large number of glass fibers, and the distributor is a relay. In a device for transmitting an optical signal, which is connected to a distributor at each location and to each distributor via at least one glass fiber, one input terminal (E) in each distributor (V) in a cascade arrangement and The branches (K) having at least two outputs (A1, A2) are connected to one another, and at each stage of the cascade arrangement, starting from the glass fibers coming from the relay point (VST), the branches (K). The other input terminal of one branch (K) is connected to each output terminal of the second input terminal (M) at least in the final stage of the cascade arrangement when viewed in the direction of the subscriber (T). The equipped branch (K) is used, A device characterized by the above. 2. Device according to claim 1, characterized in that, in the last stage of the cascade arrangement, mainly a branch (K) with only two outputs (A1, A2) is used. 3. The second input end (M) of the branch section (K) is 1
2. One plug is equipped.
Or the apparatus according to 2. 4. Device according to claim 1, characterized in that the second input (M) is optimized for reflection.