JP3233647B2 - Signal transmission system for maintenance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a maintenance signal transmission system for transmitting a maintenance signal via the same line as a main signal using a transmission line.

In an optical signal transmission system or the like, a maintenance signal such as an order wire signal is inserted into a main signal, extracted from the main signal, and transmitted and received at each station via a main transmission line.

Therefore, when the transmission line is switched to a standby line due to a failure or the like, it is necessary to similarly switch the line for transferring the maintenance signal to the standby line.

[0004]

2. Description of the Related Art In a conventional transmission system, a working line and a protection line coexist in the same cable, and if a cable is disconnected in a trunk transmission line, both the working line and the protection line are disconnected. Therefore, it cannot be remedied even if the line is switched to the backup.

Therefore, a so-called route diversity system in which the working line and the protection line are transferred by different routes (cables) has been considered.

In order to adopt the route diversity system, as in the conventional transmission system, the transmitting station inserts and sends out maintenance signals to both the working line and the protection line by using a hybrid, and the receiving station uses the hybrid. It is conceivable to adopt a system in which a switch is connected so that only the maintenance signal from one of the lines is extracted.

[0007]

However, when the receiving station switches the maintenance line reception as described above, the connection between the relay station and the receiving station in the middle of one line is disconnected. The call from the relay station to the receiving station cannot be performed, and the order wire communication cannot be performed.

Therefore, a method is conceivable in which the receiving station adds and receives signals sent from both lines without performing switch switching similarly to the transmitting station.

However, when the route of the working line and the route of the protection line are different, as in the case of a route diversity transmission line, the two routes of the signal received from the transmitting station via the two lines at the receiving station side are different. A phase shift occurs between them, which causes a problem that reception at the receiving station side cannot be performed normally.

The present invention has been made in view of such circumstances, and it is possible to always transmit a normal maintenance signal without a phase difference from a transmitting station to a receiving station. It is an object of the present invention to provide a maintenance signal transmission system that can always call a receiving station from a relay station in the middle of any of the service lines.

[0011]

In order to achieve the above object, a maintenance signal transmission system according to the present invention comprises two signal transmissions between a transmitting station 1 and a receiving station 2 as shown in FIG. In a maintenance signal transmission system in which road lines 3 and 4 are provided and a maintenance signal is transmitted from the transmission station 1 to the reception station 2 via the same line as the main signal, the transmission station 1
The transmission line selecting means 16 for selecting one line for transmitting the maintenance signal from the two signal transmission line lines 3 and 4 is provided on the receiving side. A maintenance signal adding means 23 for adding and receiving maintenance signals transmitted from both of the two signal transmission line lines 3 and 4 is provided.

The signal transmission lines 3 and 4 are optical fibers, and the two signal transmission lines 3 and 4 are optical fibers.
However, different routes may be used.

Further, a relay device is connected in the middle of the signal transmission line lines 3 and 4, and the signal transmission line lines 3, 4
The maintenance signal may be input and output from the relay device.

[0014]

The maintenance signal transmitted from the transmitting station 1 is inserted into only one line selected by the transmitting line selecting means 16 and transmitted to the receiving station 2. Therefore, the maintenance signal received by the receiving station 2 is transmitted through only one of the signal transmission lines 3 or 4.

The maintenance signals sent from the two signal transmission lines 3 and 4 to the receiving station 2 are added and received by the maintenance signal adding means 23, and the two signal transmission lines 3 and 4 are received.
The maintenance signal sent via the communication station 4 is always received by the receiving station 2.

[0016]

An embodiment will be described with reference to the drawings.

In FIG. 2, reference numeral 10 (10a, 10b) denotes a terminal equipment, and the terminal equipment 10a, 10b is connected by two cables of a working line 30 and a protection line 40 having different routes. Have been.

In the cable of the working line 30, optical fibers 31 and 32 for transmitting optical signals in both the upstream and downstream directions are arranged in pairs. Similarly, optical fibers 41 and 42 for transmitting optical signals in the upstream and downstream directions are arranged in pairs.

In the middle of the two lines 30, 40, relay devices 50, 60 are connected, respectively.

In each of the repeaters 50 and 60, a maintenance order wire signal is inserted into and extracted from each of the lines 30 and 40. 51 and 61 are telephones used for maintenance.

FIG. 3 shows each terminal device 10 (10a, 10a).
b) is shown. The maintenance order wire signal transmitted / received using the telephone 11 is transmitted to the overhead multiplexing unit (OHMU) via the order wire interface 13.
X) 14 and overhead separation unit (OHDMUX) 1
5, where it is multiplexed or separated from other maintenance signals.

At the output end of the overhead multiplexing unit 14,
A changeover switch 16 for alternately selecting an output path is connected, and each path is connected to an electric / optical unit from multiplexing units 19a and 19b which multiplex an overhead bit obtained by multiplexing an order wire signal and another maintenance signal into a main signal. One is connected to the optical fiber on the working line 30 side and the other is connected to the optical fiber on the protection line 40 side via the converters 17 and 18.

Therefore, the maintenance order wire signal is sent out via the optical fiber in one of the lines 30 or 40 selected by the changeover switch 16.

The changeover switch 16 is normally connected to the working line 30 and automatically switches to the protection line 40 when a failure occurs in the working line 30. However, a failure detection device, a drive device of the changeover switch 16, and the like are not shown.

On the other hand, the output ends of the two optical fibers that transmit the optical signal through the working line 30 or the protection line 40 separate the optical / electrical converters 21 and 22 and the overhead bit from the main signal, respectively. Separation unit (DMUX) 20a,
The output terminal of the adder 23 is connected to the input terminal of the overhead separation unit 15 via the input terminal 20b.

Therefore, the optical signal transmitted via the working line 30 and the protection line 40 is converted into an electric signal by the optical / electrical converters 21 and 22 and then converted into an electric signal.
After the overhead bits are separated from the main signal at a and 20b and then added at the adder 23, the order wire signal separated at the overhead separation unit 15 is input to the telephone 11 via the order wire interface 13. Is done.

FIG. 4 exemplifies a circuit in the adder 23 used here, and two input terminals are connected to the resistor 2.
Both are connected to the same input terminal of the operational amplifier 23c via 3a and 23b, and a resistor 23d is connected between the input terminal and the output terminal of the operational amplifier 23c. As a result, the output c on the output end side becomes the input a from the two input ends,
b is added.

In the transmission system of the embodiment configured as described above, normally, in the terminal equipment on the receiving side, the changeover switch 16 is connected to the working line 30 side, and when a failure occurs in the working line 30, the protection switch is used as a backup. Connected to line 40 side.

Therefore, the transmitting-side terminal device 10a or 1
0b, the order wire signal is always sent to the terminal device 10b or 10a on the receiving side only through one of the working or protection lines 30 or 40.

However, the terminal device 10b or 10
In a, the signals sent via both the working and protection lines 30, 40 are added and received. Therefore, no matter which side of the switch 16 is switched, the order wire signal transmitted from all the relay devices 50 and 60 is received by the terminal device 10b or 10a on the receiving side.

The changeover switch 16 is connected to the working line 3
When connected to the 0 side, the order wire signal from the relay device 60 on the protection line 40 is inserted into the pseudo signal on the line and transmitted. Further, when the changeover switch 16 is switched to the protection line 40 when the working line 30 fails, the relay device 50 on the working line 30 side
Is inserted into an alarm indication signal (AIS signal) or the like and transmitted.

The maintenance signal may be not only an order wire signal but also a supervisor signal for communication with the monitoring device and various other maintenance signals.

The present invention is not limited to a route diversity transmission line, but can be applied to a transmission line having a working line and a protection line in the same cable.

[0034]

According to the maintenance signal transmission system of the present invention, the maintenance signal transmitted from the transmitting station can always be received in the receiving station in a correct state without any phase shift or the like. There is an excellent effect that the maintenance signal can be constantly transmitted to the receiving station side from the relay device on either one of the lines.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a schematic diagram showing the overall configuration of an embodiment.

FIG. 3 is a schematic diagram illustrating a partial configuration of an embodiment.

FIG. 4 is a partial configuration diagram of an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmitting station 2 Receiving station 3, 4 Signal transmission line line 16 Changeover switch (transmission line selecting means) 23 Adder (maintenance signal adding means)

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Nishimura 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-2-253725 (JP, A) JP-A1-261034 (JP, A) JP-A-53-69510 (JP, A) JP-A-59-160333 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 1/74, 10 / 08

Claims (4)

(57) [Claims] 1. A maintenance signal transmission wherein two signal transmission lines are provided between a transmitting station and a receiving station, and a maintenance signal is inserted into a main signal from the transmitting station and transmitted to the receiving station. In the system, the transmitting station inserts the maintenance signal into the main signal.
And one line for transmission is provided to transmit line selection means for selecting from among said two signals transmission line, to the receiving station side, transmitted thereto said two signal transmission paths once line or al A maintenance signal transmission system comprising a maintenance signal adding means for adding and receiving a maintenance signal extracted from a main signal . 2. The maintenance signal transmission system according to claim 1, wherein said two signal transmission line lines pass through different routes. 3. The maintenance according to claim 1, wherein a relay device is connected in the middle of the signal transmission line, and a maintenance signal is input / output from the relay device to the signal transmission line. Signal transmission system. 4. A maintenance signal transmission system in which two signal transmission lines are provided between two terminal stations, and a maintenance signal is inserted into a main signal and transmitted between the terminal stations . In the terminal device, transmission line selecting means for selecting one line for transmitting the maintenance signal inserted into the main signal from the two signal transmission line lines, and the two signal transmission line circuits or linear or it transmitted the incoming main signal
And a maintenance signal adding means for adding and receiving a maintenance signal extracted from the maintenance signal, the terminal device of the maintenance signal transmission system.