JPH04284752A - Order wire system of ring constitution - Google Patents

Abstract

PURPOSE:To enable the order wire to be used even in the case of optical fiber interruption by providing a howling prevention section caused between a signal sent from an ad-drop device of the present station and a signal circulated through a ring on the ad-drop device. CONSTITUTION:The system is provided with ad-drop devices 100-1-100-n to insert/separate a signal to each station. The ad-drop devices are interconnected in a ring by a transmission line. Through the constitution above, the signal is sent/received among the ad-drop devices. A howling prevention section (350-1-350-n) is respectively provided on each of the ad-drop devices 100-1-100-n to prevent howling caused between the signal sent from the ad-drop device of the present station and a signal circulated through the ring. Furthermore, when the transmission line is formed by 1st and 2nd lines, even when one line is interrupted, the other line is used to continue the communication.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an order wire system used for line maintenance of a ring-configured system having an add-drop multiplexer (hereinafter referred to as ADM).

[0002] In recent years, high survivability
A system with a ring configuration is required. For this reason, SONET (Synchronous Op
tical Network) ADM Hybrid・
A ring is provided, but when using a ring configuration, in the conventional order wire system, the sound sent from the own station goes around the ring and returns, causing oscillation (howling).
, this needs to be avoided.

[0003]Therefore, there is a need for an order wire system with a ring configuration that prevents howling due to the voice transmitted from the own station and allows the use of the order wire even if the optical fiber is disconnected.

0004

2. Description of the Related Art FIG. 6 is a block diagram of a conventional order wire type system having a linear configuration.

In FIG. 6, for example, ADMs 1-1 to 1-4 of four stations A, B, C, and D and an optical transmission line 2
A communication network is formed by a linear configuration of -1 to 2-6. For example, a telephone (T
When transferring a voice signal for maintenance from EL) 3-2 to telephone (TEL) 3-1 connected to station A, TEL 3-2
From ADM1-2, optical transmission line 2-1, ADM1-1
A voice signal for maintenance is transferred to TEL 3-1 via.

[0006] Also, a telephone (TEL) 3 connected to station B
-2 to, for example, a telephone (TEL) 3 connected to station D.
Similarly, when transmitting voice signals for maintenance to TEL 3-2 to ADM 1-2 and optical transmission line 2-5,
, ADM1-3, optical transmission line 2-6, and ADM1-4
A voice signal for maintenance is transferred to TEL 3-4 via.

[0007] Also, a telephone (TEL) 3 connected to station A
-1 to a telephone (TEL) connected to station B, station C, or station D, the same method as described above is used.

[0008] In this way, maintenance audio signals are transmitted between stations in a linear configuration.

[0009]

[Problem to be Solved by the Invention] In the above-mentioned order wire system with a linear configuration, since termination is performed at both end stations (stations A and D in the case of FIG. 6), the audio sent from the local station returns to the local station. It is possible to transmit to all stations on a linear configuration without any trouble, and also to receive audio from all stations.

On the other hand, FIG. 5 shows a system in which both end stations of the linear configuration shown in FIG. The problem is that the order wire goes through one cycle and returns to the own station, causing oscillation (howling) and making it impossible to use the order wire with conventional methods.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a ring-configured order wire system that prevents howling caused by the voice transmitted from the own station and that allows the use of the order wire even when the optical fiber is disconnected.

0012

Means for Solving the Problems The above problems are solved by the configuration of the apparatus shown in FIG. That is, in Figure 1, (
Claim 1) Each station has add/drop devices 100-1 to 100-n for inserting/separating signals, and the add/drop devices 100-1 to 100-n are connected in a ring shape by a transmission path, Add/drop devices 100-1 to 100-
In a system that sends and receives signals between 350
-1 to 350-n are add/drop devices 100-1 to
100-n is a howling prevention section that prevents howling caused by the signal sent from the add/drop device of the own station and the signal that has gone around the ring.

(Claim 2) The transmission line is configured to include a first line and a second line, and when one line is disconnected, the other line is used. (Claim 3) In the order wire system with a ring configuration according to claim 1, the transmission line is composed of a first line and a second line, and when both the first and second lines are disconnected, the transmission line is disconnected. Howling prevention units 350-1 to 350-n are provided with a switching unit 700 that switches to a series connection configuration in which the two closest add/drop devices are at both ends.

[0014]

[Operation] In FIG. 1, (Claim 1) Add/drop devices 100-1 to 100-
Howling prevention parts 350-1 to 350 provided in n
-n, prevents howling caused by the signal sent from the own add/drop device and the signal that has gone around the ring.

As a result, it is possible to prevent howling caused by the voice transmitted from the own station, and it is possible to use an order wire even in a ring-configured order wire system. (Claim 2) The transmission line is composed of a first line and a second line. When one line is disconnected, the howling prevention units 350-1 to 350-n switch to use the other line. (Claim 3) When both the first and second lines are disconnected, the switching unit 700 provided in the howling prevention unit 350-1 to 350-n switches between the two lines closest to the disconnected position. Switch to a series connection configuration with two add/drop devices at each end.

As a result, when both the first and second lines are disconnected, the add/drop devices 100-1 to 100-
n are connected in series by a transmission line. Survivability equivalent to that of a normal audio signal can be maintained even in the event of a failure due to an optical fiber break.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a diagram showing the configuration of an order wire type system having a ring configuration according to an embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of the howling prevention circuit according to the embodiment. FIG. 4 is a diagram for explaining the operation of the embodiment. The same reference numerals indicate the same objects throughout the figures.

FIG. 2 shows a ring configuration of an ADM according to an embodiment of the present invention. 4 stations A, B, C, and D
DM10-1 to 10-4 are provided with howling prevention circuits 35-1 to 35-4, respectively, and FIG. 3 shows one of them.
3 shows the configuration of two howling prevention circuits 35. Each of the howling prevention circuits 35-1 to 35-4 has a howling prevention circuit 32, 32' connected to the optical transmission line (optical fiber) of the working and protection lines, respectively, as shown in FIG.

The voice signal for maintenance sent from the local telephone (TEL) 30 is sent to the howling prevention circuit 32, 32'.
Optical transmission line (optical fiber) for working and protection lines through
and the howling prevention circuit 32,
The signal is branched at 32' and added to delay circuits 40, 40'. Then, the delay circuits 40 and 40' delay the input signal by a time equal to the time required for the maintenance audio signal to go around the ring-configured optical transmission line (optical fiber) and invert the sign, and output the signal. are subtracted by circuits 50 and 50', respectively.
Add to. This is shown in FIGS. 4(a) and 4(b). In the same figure, (a) and (b) are delay circuits 40 and 4, respectively.
0' and delayed output audio signals are shown. Further, α indicates the amount of delay.

The other input terminals of the subtraction circuits 50, 50' receive maintenance audio signals received from the optical transmission lines (optical fibers) of the working and protection lines in the ring configuration as shown in FIG. 3(c). In addition, the sum of the delayed and sign-inverted audio signals input from the delay circuits 40 and 40' is calculated and output. As shown in FIG. 4(d), this output includes the error β of the audio signal caused by the amount of delay and the optical transmission line (optical fiber), so it is passed through the noise removal circuits (filters) 60 and 60', respectively. Remove noise components caused by error β.

Noise removal circuit (filter) 60, 60'
The output audio signals (in the case where howling is almost prevented, the audio signals from other stations) obtained through the SEL are applied to selection circuits (hereinafter referred to as SEL) 70 and 70', respectively. The SELs 70 and 70' are normally set to output the inputs from the noise removal circuits (filters) 60 and 60', respectively. Further, the contacts 80 and 90 of the switch connected to the outputs of the SELs 70 and 70' are normally the contacts 80 of the switch connected to the output of the howling prevention circuit 32 connected to the optical transmission line (optical fiber) of the working line. is turned on, and the contact 90 of the switch connected to the howling prevention circuit 32' connected to the optical transmission line (optical fiber) of the protection line is turned off.

In this way, the S in the howling prevention circuit 32 connected to the optical transmission line (optical fiber) of the working line is
The output of EL70 is sent to TEL3 via the contact 80 of the switch.
Add to 0. Note that the above operation is performed at stations A, B, and C shown in Figure 2.
The present invention can be applied to either the howling prevention circuit provided in the ADM of the station or the D station.

As a result, it is possible to prevent howling caused by the audio signal sent from the local station. Next, when the optical transmission line (optical fiber) of the above-mentioned working line is disconnected, the contact 80 of the switch in the howling prevention circuit 35 shown in FIG. 3 is turned off, and the contact 90 of the switch is turned on. Then, the same operation as described above is performed, and the output of the howling prevention circuit 32' is applied to the telephone (TEL) 30 via the contact 90 of the switch. By using the optical transmission line (optical fiber) of the protection line, howling caused by the voice signal sent from the own station is prevented.

Furthermore, if the optical transmission line (optical fiber) of the working and protection lines is disconnected between the same stations, for example, the optical transmission line (optical fiber) between stations B and C in the ring configuration shown in FIG. )
If 20-5 and 20-2 are disconnected at the same time, station B-
Since stations A-D-C change to a linear configuration along this route, the audio signal sent from the local station does not return to the local station.

For this reason, each station uses a control signal from a control circuit (not shown) to control the SELs 70 and 70' in the howling prevention circuits 32 and 32' shown in FIG. (Input terminal e in Figure 3
, e'). However, in order to receive audio signals from all stations, the contacts 80 and 90 of the switch shown in FIG.
Orderwire communication is restored by turning on both and receiving from both the working and protection lines.

[0027]

[Effects of the Invention] As explained above, according to the present invention, two
Order wires can also be used in the order wire method of the SONET ADM hybrid ring configuration using optical fibers.

[0028] Furthermore, survivability equivalent to that of a normal audio signal can be maintained even against failures such as optical fiber breaks.

[Brief explanation of the drawing]

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

FIG. 2 is a configuration diagram of an order wire system with a ring configuration according to an embodiment of the present invention;

FIG. 3 is a block diagram showing the configuration of the howling prevention circuit of the embodiment;

FIG. 4 is a diagram for explaining the operation of the embodiment;

[Figure 5]
is a diagram of an order wire system system with an example ring configuration.

FIG. 6 is a configuration diagram of a conventional order wire type system with a linear configuration.

[Explanation of symbols]

350-1 to 350-n are howling prevention parts, 700
indicates a switching section.

Claims (3)

[Claims] [Claim 1] An add-on that inserts/separates signals for each station.
The add/drop devices (100-1 to 100-n) are connected in a ring shape by a transmission path, and the add/drop devices (100-1 to 100-n) are connected in a ring shape by a transmission path.
In a system that transmits and receives signals between the add/drop devices (100-1 to 100-n), the add/drop device (100-1 to 100-n)
0-n), a howling prevention unit (350-1 to 350-n) that prevents howling caused by the signal sent from the add/drop device of the own station and the signal that has gone around the ring.
) Order wire system with a ring configuration. 2. The ring according to claim 1, wherein the transmission line includes a first line and a second line, and when one line is disconnected, the other line is used. Order wire method of configuration. 3. In the ring-configured order wire system according to claim 1, the transmission line is composed of a first line and a second line, and when both the first and second lines are disconnected, the disconnection occurs. A switching unit (70
0) Howling prevention part (350-1 to 350-n)
Order wire system with ring configuration.