JPS63173429A - Line supervisory system - Google Patents

Abstract

PURPOSE:To switch the system immediately to a standby system in the even of a faulty active system by supplying a line signal and a pseudo signal of the same frame constitution to the standby line so as to always check the standby line in a communication system provided with the standby line. CONSTITUTION:A transmission side protection switch 10 has two switch sections A, B, a line input signal is connected to a contact (b) of the A switch and a contact (a) of the B switch and the pseudo signal B is connected to a contact (a) of the A switch and a contact (b) of the B switch. When an input interruption detection circuit 3 detects a trouble such as signal interruption, a transmission protection switch 10 and a reception protection switch 12 are switched from the contact (a) to the contact (b) to use the standby optical system. The pseudo signal is a signal of the same frame constitution, then an input interruption detection circuit 3' always monitors the standby optical system. Moreover, the receiver side optical terminal station equipment 2' monitors the system from a monitor terminal 4' to attain the error performance check till the remote end U/B circuit without disconnecting the line.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Application Fields Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems Effects of the Invention [Summary] One or more working lines and In a communication system equipped with a backup line that is switched to use when the working line fails, a pseudo signal having the same frame structure as the line signal is supplied to the backup line,
This enables constant checking of backup lines.

[Industrial application field]

The present invention relates to a line monitoring system.

For example, in data transmission systems such as digital optical transmission systems or communications, backup lines are provided in case a line in use goes down.

Normally, one protection line is provided for multiple working lines (N), but when the working line goes down, it must be immediately switched to use. Therefore, the status of the protection line is constantly checked and it is normal. must be kept in condition.

[Conventional technology]

FIG. 3 shows an example of a conventional system that detects when a working line goes down and switches to a protection line. The figure takes a digital optical system as an example, and although only one line is shown as the working line, it goes without saying that it can be expanded to N lines.

In FIG. 3, 31 is the active optical system;
1 is a standby side optical system. Line input from the left end is via the transmission side protection switch 30.
The signal is transmitted through the active optical system 31 and the receiving switch 32 to the next system or various types of devices.

The optical system 31 on the active side consists of an end station device 33 on the transmitting side, an optical terminal device 34 on the receiving side, and a transmission 'Ia41 such as an optical fiber that connects them. The transmitting end station device 33 is
The B/U circuit 35 converts bipolar signals into unipolar signals, and the input disconnection (S I
The receiving side optical terminal equipment 34 has an LJ/B circuit 39 and a U link 40 for converting a unipolar signal into a bipolar signal.
It is equipped with The standby optical system 31' has the same configuration as the active optical system 31, and each part has the same number with a dash (゛).

In such a system, a line input is input from the leftmost terminal to the active optical system 31 via the transmitting protection switch 30 that operates as a protection switch.

That is, the line input is input to the transmitting optical terminal device 33 via the B-side contact a of the switch 30. In the optical terminal device 33, the input signal passes through the U link 38, is converted into a signal by the B/U circuit 35, and is multiplexed and converted into an electrical signal.
After receiving the optical signal conversion (MUX, Elo), the optical transmission line 41
sent to.

The receiving optical terminal device 34 performs photoelectric conversion, returns the multiplexed signal to its original form, returns the unipolar signal to a bipolar signal, and transmits it to the next stage via the receiving protection switch 32.

During such operations, if there is an accident such as a signal disconnection in the B/U circuit 35 or transmission line, the input disconnection detection circuit 36 detects this, sends it to the alarm circuit, and turns on the protection switch 30.32. Then, the human power signal is switched to the standby optical system 31'.

As a result, the line input is now transferred to the standby side optical system 31.
′ and then sent to the next stage.

[Problem that the invention seeks to solve]

The standby optical system 31' must be able to be immediately switched over and used when the active optical system fails. However, in the conventional standby side optical system, in its standby state,
Since no signal is input to the system, the input loss detection circuit always detects a failure condition, and to prevent an alarm signal from being generated, the input loss detection circuit is kept in an off state.

Therefore, in the conventional system, the standby side optical system 3
1', a circuit failure up to the input disconnection detection circuit cannot be automatically detected in the standby state, so there is a possibility that the line will go down after switching to the active state. For this reason, it is necessary to periodically inspect the standby side optical system.

For inspection of the standby side optical system, use U-links 38' and 40'.
This is done by removing the standby optical system and separating it from the entire system. However, if a failure occurs in the current optical system during this inspection, the protection switch 30
, 32 will operate and switch to the backup optical system, but since the U-links 38' and 40' have been removed, the backup optical system cannot be used as is, so the U-link is connected. A problem arises in that there is no reserve function until then.

[Means for solving problems]

FIG. 1 is a diagram showing the principle of the present invention for solving the above problems.

In FIG. 1, 11.11' is an optical transmission system, 11 is a working optical system, and 11' is a backup optical system. 10, I2 is a protection switch for switching between the active optical system 11 and the standby optical system 11'; 10 is a transmission side protection switch;
12 is a protection switch on the receiving side. Each optical system is provided with a transmitting optical terminal device 1.1' and a receiving optical terminal device 2.2'.
An input disconnection detection circuit 3.3' for detecting disconnection of an input signal is provided at the receiving end station device, and a monitor terminal 4.4' is provided, respectively. In addition to the line input terminal, the input terminal of the transmitting switch 10 has a pseudo signal 13 of the same frame as the line input terminal.
In normal use, the line human input signal is connected to the active optical system 11, and the pseudo signal 13 is connected to the backup optical system 11'. Therefore, when in use, both systems are monitored by the input disconnection detection circuit.

[Effect]

As described above, in this invention, the pseudo signal of the same frame as the line signal is also added to the protection optical system 11', so that the input disconnection detection circuit of the protection optical system is always operating. This makes it possible to constantly monitor circuits up to the B/U circuit.

Also, with this pseudo signal, error performance ticks up to the far end U/B circuit can be performed at the far end monitor output without disconnecting the line.

〔Example〕

FIG. 2 shows an embodiment of this invention. The same parts as in FIG. 1 are given the same numbers, so a detailed explanation will be omitted.

The transmission side protection switch 10 used in the present invention has two switch sections AS8, and connects a line input signal to a contact point b on the A switch side, a contact a on the B switch side,
Connect the pseudo signal B to the contact a of the A switch and the contact S of the B switch.

In normal operating conditions, as shown in the figure, the line input is connected to the active optical system 11 via contact a of the B switch,
The pseudo signal is connected to the standby optical system 11' via contact a of the A switch. At this time, in order to take out the output of the working optical system 11, the receiving protection switch 12 is connected as shown. Each optical terminal equipment 1.1' on the transmitting side has a B/U circuit 5.5.
In addition to ', an input disconnection detection circuit 3.3' is provided.

The optical terminal equipment 2.2' on the receiving side includes a U/B circuit 6.6'.
Besides, monitor terminal 4 for error performance check
．． 4' is provided.

In such a state, when the input disconnection detection circuit 3 detects a trouble such as a signal disconnection, it connects the transmitting side protection switch 10 and the receiving side protection switch 12 to the opposite contacts from the illustrated contacts, and connects the backup side optical system. will be used. That is, in the transmission side protection switch 10, from each contact point a of switch A1 switch B, to each contact point a of switch A1 switch B of the reception side protection switch 12.
Switch from to contact.

As described in conjunction with the explanation of the principle diagram in FIG. 1, in the present invention, the pseudo signal 13 is also connected to the standby optical system 11' side. This pseudo signal is a signal with the same frame structure as the line input, so the input disconnection detection circuit always monitors the standby optical system. In addition, since the receiving end station device 2' is equipped with a monitor terminal 4', by monitoring from this terminal, it is possible to check error performance up to the far end U/B circuit without disconnecting the line. It is.

Therefore, the U-link used in the conventional example is completely unnecessary.

C. Effects of the invention] As described above, according to the present invention, there is no need for a U-link at all, and the standby side optical system is constantly monitored, so that if the current system fails, the standby side optical system is immediately activated. It can be used by switching to a side light system, increasing the reliability of the entire system.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of this invention, FIG. 2 is an embodiment of this invention, and FIG. 3 is a diagram showing a conventional example. 1.1'...Sending side optical terminal equipment 2.2'-...Receiving side optical terminal equipment 3.3'--Human power failure detection circuit 4.4'--Monitor terminal 5.5'-Bipolar /unipolar conversion circuit 6.6'-
Unipolar/bipolar conversion circuit 7,7'--Optical transmission line 10--Transmitting side protection switch 12-Receiving side protection switch Fig. 1 * &, #l+ Fig. 2

Claims (1)

[Scope of Claims] A communication system comprising one or more working lines, a protection line to be switched and used in the event of a failure of the working line, and an input disconnection detection means for detecting disconnection of an input signal, comprising: A pseudo signal output means (13) for outputting a signal, and a switching means (10) for switching between a working line and a protection line are provided, and a pseudo signal is always applied to the protection line so that it can be checked at all times. Line monitoring method.