JPH084248B2 - Optical line switching method - Google Patents

Description

The present invention relates to a method for switching a switching section line section of a working optical line with a switching optical line.

"Prior art" Generally, communication cables in urban areas and suburbs are often switched to new cables or detour routes due to changes in laying routes due to cable failures, cable relocation, etc. When switching, the current communication must be cut off immediately.

To do this, both ends have a light-transmitting end (E / O) and a light-receiving end (O
/ E), it is necessary to synchronize the switching section line section with the switching optical path (optical cable) at both ends of the switching section line section and instantly switch the switching section line section to the switching optical line. .

As a means for achieving the above-mentioned synchronization, it has been proposed that the switching devices interact with each other via a working optical line, a metal line for communication existing in the switching optical line, and a modem.

[Problems to be Solved by the Invention] In the case of the switching synchronizing means described above, it is essential that at least one of the working optical line and the switching optical line has a communication metal line, and the working optical line and the switching optical line. Depending on the type, the metal wire for communication may not be secured.

Under these circumstances, there is a demand for a method that can achieve switching synchronization even when there is no metal wire for communication when switching the optical line.

In view of the above problems, the present invention aims to provide an optical line switching method capable of switching synchronization without a communication metal wire.

[Means for Solving Problems] In order to achieve the intended purpose, the present invention uses an arbitrary section line portion between the light-transmitting end portion and the light-receiving end portion of the working optical line as a switching section line portion, In the method of switching the switching section line section to the switching optical line, an optical synchronization signal is made incident on the working optical line from a position closer to the light-transmitting end than the switching section line section, and the optical synchronization signal is transmitted to the switching section line section. It is characterized in that switching is synchronized by detecting at a plurality of switching points corresponding to both ends.

[Examples] Examples of the method of the present invention will be described below with reference to the drawings.

In FIG. 1, a working optical line 1 consisting of an optical cable
Is a light-transmitting end 2 having an E / O at one end and an O / E at the other end.
And a light-transmitting end 2 having a light-receiving end 3 having
Are arranged in one station, and the light-receiving end portion 3 is arranged in another station.

Each section line portion 1a, 1b, 1c, 1d, 1e of the working optical line 1 is
They are connected to each other via the optical connector 4,
Section line section 1a and light transmitting end section 2, section line section 1e and light receiving end section 3
Are also connected to each other via the optical connectors 4.

In the illustrated example, the section line portions 1c and 1d of the working optical line 1 are set in the switching section line portion 5, and the front end and the rear end of the switching section line portion 5 are the front side switching point P ₁ and the rear side switching point P, respectively. _{It is 2} .

The switching optical line 6 composed of an optical cable is composed of line sections 6c and 6d having substantially the same length as the above-mentioned section line sections 1c and 1d, which are connected to each other via an optical connector 4, and the ends of the line sections 6c and 6d. The optical connector 4 is also attached to the section.

The optical coupler 7 is provided at a position rearward of the light transmitting end 2 of the working optical line 1 and forward of the front switching point P ₁ of the switching section line portion 5, and the optical coupler 7 includes A light source 8 for inputting an optical synchronization signal to the working optical line 1 is connected.

As an example of the optical coupler 7, an optical multiplexer / demultiplexer is adopted to minimize the optical insertion loss.

At both switching points P ₁ and P ₂ of the working optical line 1, detection means 9 and 10 for detecting an optical synchronization signal by the local detection method are provided.

In FIG. 1, when the switching section line part 5 of the working optical line 1 is switched to the switching optical line 6, both switching points P ₁ and P ₂ have a modem and a switching mechanism part for switching synchronization. A switching device (not shown) is provided, and line switching is performed in a predetermined procedure.

Such line switching is performed in a state where the working optical signal S ₁ is transmitted to the working optical line 1, and at this time, the optical synchronizing signal S ₂ from the light source 8 is transmitted through the optical coupler 7 to the working optical line 1 And the optical synchronization signal S ₂ is detected by the detecting means 9 and 10 at the switching points P ₁ and P ₂ to establish switching synchronization.

Specifically, the sync pulse as shown in FIG.
It is incident on the working optical line 1 as S ₂ , and the local detection method shown in FIG. 3, that is, by bending a predetermined part of the section line parts 1c and 1d to leak the optical synchronization signal S ₂ to the outside of the working optical line 1, The leaking optical synchronizing signal S ₂ is detected by the detecting means 9 and 10 to establish the switching synchronization.

In order to facilitate local detection at this time,
It is desirable that the optical synchronization signal S ₂ has a longer wavelength than the working optical signal S _{1 such} that S ₂ = wavelength 1.55 μm and S ₁ = wavelength 1.3 μm.

The optical synchronization signal S ₂ may carry more complicated information than that shown in FIG. 2 as a pulse code string.

When the working optical line 1 is provided with a spare optical fiber core wire, the light source 8 is connected to the spare optical fiber core wire on the light transmitting end 2 side of the working optical fiber line 1 and the working optical fiber line 1 is used in this mode. The optical synchronization signal S ₂ may be made incident on.

In addition, even if the optical synchronization signal S ₂ is applied to the working optical line 1, if the switching device is not in the operation startable state, the predetermined line switching is not performed, and the switching device at one switching point starts operation. Although it is possible, when the switching device at the other switching point is not in a state in which the operation can be started, if the optical synchronization signal S ₂ is sent, the line switching will be performed at only one point, and the communication will take a long time. There are things that can be bad.

From this point of view, when the optical synchronization signal S ₂ is sent, it is necessary to confirm that the switching devices provided at the switching points P ₁ and P ₂ are ready to start operation.

To cope with this, optical loss due to the local detector in both switching points P _1, P _2, i.e., the loss of light synchronizing signal S ₂ that caused intentionally in both switching points P _1, P _2, 4th As shown in the figure, a filter for monitoring with an optical wavelength loss measuring device 11 based on the OTDR method or transmitting the working optical signal S ₁ to the light receiving end 3 side of the working optical line 1 but reflecting the optical synchronizing signal S ₂ And the reflected optical synchronization signal S ₂ may be monitored on a test stand in the station connected to the light transmitting end 2 side of the working optical line 1.

The optical synchronization signal S _{2 in} this case also serves as test light for the above-mentioned operation confirmation.

[Advantages of the Invention] As described above, according to the optical line switching method of the present invention, since switching synchronization can be achieved via the working optical line, a metal wire for communication is not required, and a plurality of working optical lines can be used. When switching the section line section, the metal wire for communication is not required.

[Brief description of drawings]

In the drawings showing an embodiment of the method of the present invention, FIG. 1 is an explanatory view showing switching correspondence between a working optical line and a switching optical line, and FIG. 2 is an explanatory view showing a pulse waveform of an optical synchronization signal. ,
FIG. 3 is an explanatory view showing the detection status of the optical synchronization signal, and FIG. 4 is an explanatory view schematically showing one means for confirming the status of the switching device. 1 ... Working optical line 1a to 1e ... Sectional line section of working optical line 2 ... Transmitting end of working optical line 3 ... Receiving end of working optical line 4 ... Optical connector 5 ... Switching section line Part 6 …… Switching optical lines 6c, 6d …… Switching optical line section 7 …… Optical coupling part 8 …… Optical synchronizing signal light source 9,10 …… Optical synchronizing signal detection means S ₁ …… Currently used Optical signal S ₂ …… Optical synchronization signal P ₁ , P ₂ …… Switching point

Claims (2)

[Claims] 1. A method of switching a switching section line section to a switching section line section, wherein an arbitrary section line section between a light-transmitting end portion and a light-receiving end section of a working optical line section is used as a switching section line section. The optical synchronization signal is made incident on the working optical line from a position closer to the light-transmitting end than the optical fiber, and the optical synchronization signal is detected at multiple switching points corresponding to both ends of the switching section line section to establish switching synchronization. A method of switching optical lines characterized by. 2. A rear side of a light transmitting end portion of a working optical line, and
The optical line switching method according to claim 1, wherein an optical coupler is provided at a position in front of the front switching point of the switching section line portion, and an optical synchronization signal is incident through the optical coupler.