JPS61120535A - Transmission system - Google Patents

Abstract

PURPOSE:To transmit only ordering information even when one transmission line is faulty by adding an inexpensive switching circuit to input/output points of a terminal station without adding an expensive line switch and a spare transmission line to both terminal stations. CONSTITUTION:If a fault takes place in a middle point 10 of a transmission line 7, a main data signal including an ordering information signal transmitted from a C station 3 is transmitted to a B station 2 via a transmission line 6, while the main data signal including the ordering information signal transmitted from a B station 2 is not transmitted to the C station 3 because of a fault at the middle point 10. Thus, the ordering information signal is transmitted from the B station 2 to the C station 3 by switching switch circuits 2a, 2l of the B station 2 and switch circuits 3f, 3g of the C station 3 as shown in figure by using an external switch signal. In transmitting the ordering information from the C station 3 to the B station 2, the information is transmitted by restoring the switch circuits 2a and 3f by using the external switch signal. Thus, the switch circuits 2a, 3f repeat alternately transmission and reception.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmission system, and particularly to a transmission system for meeting information signals in a small capacity optical digital transmission system.

[Prior art]

Generally, in a digital transmission system, it is essential to provide a transmission path for meeting information signals in addition to a transmission path for main data. This meeting information signal is information used for a meeting from the failure point to the terminal station or from the terminal station to the opposite station's terminal station when a failure occurs in a transmission line or repeater of a digital transmission system, and when the failure is repaired. Generally, the transmission path for transmitting this meeting information uses a separate intervening channel within the cable that serves as the transmission path for the main data signal.
In recent years, in optical fiber communications, for example, for the purpose of lightning protection, the use of intervening metal wires has been stopped, and the main data signal transmission path consisting of optical 7-eyepers is commonly used as the transmission path for meeting information signals.

This sharing is accomplished, for example, by adding a code pie orientation rule or a spare bit to the main data signal, and by separating or combining it from the main data signal at the terminal station.

[Problem that the invention seeks to solve]

As described above, in conventional transmission systems, when a transmission line such as an optical fiber or an intermediate repeater fails, the main data signal is not being transmitted, so the meeting information signal cannot be transmitted either. Therefore, in the conventional transmission method, it is known to provide a line switching device at both end stations and one each for sending and receiving a backup transmission line, but one end station device or intermediate relay device is also required at each end station. It was also very economical, and had drawbacks such as being difficult to put it into practical use, especially in small-capacity digital transmission systems that pursue economic efficiency, or subscriber line transport systems that are applied to depopulated areas. .

[Means for solving problems]

The transmission method according to the present invention includes a switching circuit at an input/output point J of a transmission line on the transmitting side and a transmission line on the receiving side of a terminal device or an intermediate relay device, and switches between the switching circuits at this input/output point J. By connecting through a line, it is possible to make communication possible through a common transmission path for transmission and reception in the event of a failure in one of the transmission paths.

[Effect]

In this invention, by adding an inexpensive switching circuit to the input/output point of the terminal station, it is possible to transmit only the meeting information even if one transmission line becomes a failure.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a transmission system according to the present invention. In the figure, 1 is the terminal equipment installed in the 7-stem end station I (hereinafter referred to as station A), 1a is the switching circuit, 1b is the optical-to-electrical conversion circuit, and 1c is the main data signal and meeting information signal. Branch circuit to separate, 1d#
:l: Main data input terminal in A station, 1e is switching circuit, 1f is electric-optical conversion circuit, 1g is coupling circuit, 1h
is the main data output terminal at station A, 11 is the input terminal, 1
j is an output terminal, 1 is a switching line, 2 is a terminal relay device or intermediate relay device installed at an intermediate station of the system (hereinafter referred to as B station), 2a is a switching circuit, 2b is an optical-to-electrical conversion circuit, 2c is a branch circuit that separates the main data signal and the meeting information signal, 2d is a coupling circuit, 2e is an electrical-to-optical conversion circuit, 2f and 2g are switching circuits, 2h is an optical-to-electrical conversion circuit, and 21 is a main data signal and 2j is a coupling circuit, 2 is an electric-optical conversion circuit, 21 is a switching circuit, 2m and 2n are switching lines, 2p is a first input terminal, 2q is a first output terminal,
2r is a second input terminal, 2S is a second output terminal, 2t and 2u are internal transmission lines, 3 is a terminal relay device or intermediate relay device installed at a system intermediate station (hereinafter referred to as C station), 3
a is a switching circuit, 3b is an optical-electrical conversion circuit, 3c is a branch circuit that separates the main data signal and the meeting information signal,
3d is a coupling circuit, 3e is an electrical-optical conversion circuit, 3f and 3g are switching circuits, 3h is an optical-electrical conversion circuit, 31 is a branch circuit that separates the main data signal and the meeting information signal, 3j is a coupling circuit, 3 3 is an electric-optical conversion circuit, 3 is a switching circuit, 3m and 3n are switching lines, 3p is a first input terminal, 3q is a first output terminal, 3r is a second input terminal, 3s is a second output terminal, 3t and 3u is an internal transmission line,
4 and 5 are optical fiber cable transmission lines connected between A station 1 and 3 station 2, and 6 and 7 are optical fiber cable transmission lines connected between 3 station 2 and 0 station 3.
an optical fiber cable transmission line connected between
Reference numeral 9 indicates a transmission line of an optical fiber cable having one end connected to 0 stations, and 10 indicates an intermediate point of the transmission line 7, which indicates the point where a failure has occurred.

Next, the operation of the transmission system with the above configuration will be explained with reference to FIGS. 2 and 3. First, to explain the case where there is no failure on the transmission line and the main data signal and the meeting information signal are transmitted smoothly, the main data signal including the meeting information signal is transmitted from the lower station 0 station 3 to the transmission line 6. The signal is input to the switching circuit 2a of BNIJ2 via the signal. This switching circuit 2a is not switched, as shown in FIG. 1, because there is no fault in the transmission path. Therefore, the main data signal including the meeting information signal is input to the optical-to-electrical conversion circuit 2b1 via this switching circuit 2a,
Converts optical signals into electrical signals. This converted electrical signal is input to the branch circuit 2C, and from this branch circuit 2ct,
It is separated into a main data signal and a meeting information signal. This meeting information signal is output from the second output terminal 2S. On the other hand, the meeting information signal of the B station is inputted from the first input terminal 2p, coupled to the main data signal by the coupling circuit 2dJ, and inputted to the electro-optical conversion circuit 2C.

Therefore, after being converted into light by this electrical-optical conversion circuit 2e, it is input to the switching circuit 2f. At this time, the switching circuit 2f is not switched as shown in FIG. 2 because there is no failure in the transmission line 1c. For this reason,
The main data signal containing the meeting information signal converted into light is sent to the transmission line 4 via this switching circuit 2f. Similarly, the main data signal containing the meeting information signal is input from the upper station A 1 to the switching circuit 2g of the three stations 2 via the transmission line 5. This switching circuit 2g is not switched because there is no fault in the transmission path. Therefore, the main data signal including the meeting information signal is transmitted to which switching circuit 2.
The optical signal is converted into an electrical signal through the optical-to-electrical conversion circuit 2h.

This converted electric signal is input to the branch circuit 21,
The main data signal and the meeting information signal are separated from this branch circuit 2 itself. This meeting information signal is output from the first output terminal 2q. On the other hand, this B
The station meeting information signal is inputted from the second input terminal 2r, combined with the main data signal by the coupling circuit 2, and inputted to the electrical-to-optical conversion circuit 2kj.

Therefore, after being converted into light by the electro-optical conversion circuit 2, the light is input to the switching circuit 211. At this time, since there is no failure in the switching circuit 2111m feed path, the second
As shown in Figure 1, this is not switched. For this reason,
The main data signal containing the meeting information signal converted into light is sent to the transmission line 7 via this switching circuit 2f.

Next, a case will be described in which a failure occurs at the intermediate point 10 of the transmission line 7 that connects station 3 2 and station 0 3. In this case, the main data signal including the meeting information signal sent from station 0 3 is sent to station 3 2 via transmission line 6, but since there is no moss failure in transmission line 6 #, communication is possible normally. .

However, the main data signal containing the meeting information signal sent from Bsz cannot be sent to station 0 3 because there is a failure at intermediate point 10 of transmission line 7, and communication becomes impossible.

Therefore, when sending the main data signal containing the meeting information 1N from the 3rd station 2 to the 0th station 3, if an external switching signal is input to the switching circuits 2a and 21, the switching circuits 2a and 21 will be operated as shown in FIG. can be switched to

Therefore, the meeting information signal is transmitted to the coupling circuit 2j of the three stations 2.
is combined with the main data signal and inputted to the electrical-optical conversion circuit 2k. Therefore, as shown in FIG. 3, the main data signal containing the meeting broadcaster's code converted into light by the electro-optical conversion circuit 2 is transmitted through the switching circuit 21 - switching mechanism 2n - switching circuit 2a - It is input to the 0 station 3 via the transmission line 6. On the other hand, in station 0 3, when external switching signals are simultaneously input to switching circuits 3f and 3g, switching circuits 3f and 3g are switched as shown in FIG. Therefore, the main data signal including the meeting information signal input to station 03 is as shown in FIG.
Switching circuit 3f - switching line 3m - switching circuit 3
It can be input to the optical-to-electrical conversion circuit 3h via g. In this way, the meeting information signal input from the second input terminal 2r of station 3 2 can be transmitted to station 0 3.

In addition, when transmitting meeting information from station 0 3 to station 3 2, switching circuits 2a and 21 are switched back by an external switching signal, so that the main data signal including the meeting signal from station 0 3 is switched to station 0 3. times'e63f
- Input to the switching circuit 2a of the B station via the transmission line 6.

Therefore, since this switching circuit 2a is switched back, the main data signal containing the meeting signal is inputted to the optical-to-electrical conversion circuit 2b via this switching circuit 2a, and is converted into an electrical signal. Then, this converted electrical signal is input to the branch circuit 2c and divided. Therefore, the meeting information signal is output from the second output terminal 2S.

Note that the switching circuits 2a and 3f need to alternately repeat transmission and reception, and the internal transmission lines 2n and 3m
It goes without saying that the cases where the electrical-optical conversion circuit 3e and the optical-electrical conversion circuit 2bj are connected are alternately repeated. In addition, in general, the transmission lines for transmission and reception are maintained separately in the meeting round m1i4W, and although it is ideal to transmit the transmission and reception signals at the same time, in the event of a failure in such a transmission line, ,
Even if transmission and reception are performed in time division, there is a big problem in practical use.
Of course, this is not possible.

〔Effect of the invention〕

As explained in detail above, according to the transmission method according to the present invention, inexpensive switching circuits can be added to the input/output points of the terminal stations without adding expensive line switching devices and backup transmission lines to both terminal stations. By doing so, even if one of the transmission lines becomes impaired, only the meeting information can be transmitted t-aT.
It is possible to create an economical system configuration that enables Moreover, even if the main data cannot be transmitted due to a failure in the transmission path, only the meeting information can be communicated using NQI. Therefore, it is particularly effective for small-capacity communication systems or subscriber transport systems targeted at depopulated areas.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the transmission system according to the present invention, and FIGS. 2 and 3 are block diagrams for explaining the operation of FIG. 1. ” 1@116@terminal device (A station), 72.16・**
O switching circuit, 1b...e optical-electrical conversion circuit, IC
...e branch circuit, 1d... main data input terminal, 1
f...Electric-optical conversion circuit, 1g...Fist/coupling circuit,
1h...Main data output terminal, 11...-Input terminal, 1j11e...Output terminal, 1...Switching line, 2 fist--Terminal relay device or intermediate relay device, 2a,
2f, 2g, 21... switching circuit, 2b, 2h...
... Optical-electric conversion circuit, 2C12i ... Branch circuit, 2d, 2j ... Combined circuit, 2e #2 ...
Electrical-optical conversion circuit, 2m and 2n... switching line, 2p... first input terminal, 2q... first output terminal, 2r... second input terminal, 28-...・Second output terminal, 2t and 2u...internal transmission line, 4 to 9・
...-Transmission line, 10 Φ... intermediate point.

Claims (1)

[Claims] In a transmission method that superimposes a meeting information signal on the main data signal and uses only two transmission paths, transmission and reception, to transmit the main data signal and the meeting information signal, the transmission is performed on the sending side of a terminal device or intermediate relay device. By providing a switching circuit at the input/output point to the transmission line and the receiving side transmission line, and connecting the switching circuits at the input/output point with a switching line, transmission and reception can be shared by the same transmission line in the event of a failure in one transmission line. A transmission method that is characterized by being able to communicate over the road.