JPH0454410B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention provides a method for connecting a low-speed meeting line to a high-speed main signal.
The present invention relates to an economical method for transmitting meeting line signals between two stations having a plurality of parallel end station devices that insert and transmit OW signals.

(b) Technical Background Figure 1 is a block diagram of an optical fiber transmission system.

In the figure, 1 and 2 are optical terminal equipment, 3 and 4 are meeting line (hereinafter referred to as OW) units, 5 is an optical fiber cable, 6 and 12 are input interface circuits,
7, 13 are code conversion circuits, 8, 14 are electrical/optical conversion circuits, 9, 15 are output interface circuits, 1
0 and 16 are code demodulation circuits, 11 and 17 are optical-to-electric conversion circuits, 18 and 21 are analog-to-digital converters (hereinafter referred to as A/D converters), and 19 and 22 are digital-to-analog converters (hereinafter referred to as D /A converter), 20 and 23 indicate telephones.

In the optical fiber transmission system, since the optical fiber is an insulator, it is less susceptible to the effects of earth potential differences, various electromagnetic inductions, lightning, etc.
The signal is also often superimposed or inserted into the main signal using techniques such as code conversion, and then transmitted through the optical fiber cable 5.

(b) Prior art and problems Main signal transmission between stations is not limited to just one line, but may include multiple lines placed in parallel. FIG. 2 shows its block diagram. Conventional OW signal transmission and reception will be explained below using FIG.

FIG. 2 is a block diagram of a system showing transmission and reception of OW signals between offices having a plurality of conventional optical terminal equipment.

In the figure, 24 to 29 are optical terminal equipment, and 30 to 35 are
OW unit, 36 indicates an optical fiber cable.

As shown in FIG. 2, each station has a plurality of optical terminal equipment 24.
In a system having OW units 30-32, 33-35 for each line, it is uneconomical to have OW units 30-32, 33-35 for each line. That's enough. However, if the OW signal is transmitted using only one specific line, if that line happens to become a failure, the OW signal will not be able to be transmitted. For this reason, conventionally, as shown in Figure 2, each line
Since it has OW units 30-32 and 33-35, it has the disadvantage of being uneconomical.

(d) Object of the invention In view of the above-mentioned drawbacks, the object of the invention is to
The goal is to provide an OW signal transmission system.

(e) Structure of the invention According to the present invention, in a configuration in which three or more pairs of terminal station devices connecting a main signal line for transmitting high-speed main signals between two stations are arranged in parallel, each station can The system is equipped with one meeting line unit that encodes a telephone signal for a meeting with the opposite station and transmits and receives it as an OW signal, and one switching circuit for selecting the received OW signal. The signal is inserted into the high-speed main signal between all end station equipment and transmitted, and the switching circuit at the opposite station receives a signal indicating that the main signal line from the previous end station is normal. failure of the main signal line from the terminal station that was sending the OW signal to the meeting line unit and blocking OW signals from other terminal stations that have a normal main signal line. and a signal indicating that the main signal line of the terminal station in the next order is normal, sends the OW signal from the terminal station in the next order to the meeting line unit, and has a normal main signal line. This is achieved by a meeting line signal transmission system characterized by having a function of blocking OW signals from other terminal stations.

(f) Embodiment of the invention An embodiment of the invention will be described below with reference to the drawings.

FIG. 3 is a system block diagram showing OW signal transmission and reception between two stations A and B having a plurality of optical terminal devices according to an embodiment of the present invention, and FIG. 4 is a normal transmission line according to an embodiment of the present invention. FIG. 2 is a block diagram mainly consisting of a circuit that selectively receives one of a plurality of OW signals received from a plurality of OW signals.

Components with the same functions as those in FIG. 2 are indicated by the same symbols, 37 and 38 are switching circuits with the same functions, 39 is a D/A converter, 40 is a telephone, 41 to 43 are AND circuits, 44 is an OR circuit, Reference numerals 45 and 46 indicate knot circuits, and r1 ₁ to _{r1 3} indicate ALM contacts of alarm relays that issue an alarm when the receiving state becomes abnormal.

The contents of the OW units 30 and 33 and the contents of the optical terminal equipment will be explained using FIG. 1 and the case where an OW signal is transmitted from station A to station B in FIG. 3.

The analog OW transmission signal from the telephone 20 of the OW unit 3 shown in FIG. The signal is sent to the code conversion circuit 7 shown in FIG. 1, and is transmitted to station B along with the main signal by means of service bits inserted into the high-speed main signal. At the B station, the OW signals are extracted from the code demodulation circuits 16 shown in FIG.
Send to 8. The switching circuit 38 selects one of the OW signals extracted from the normally transmitted signals and sends it to the OW unit 33. In OW unit 33, Figure 1
The D/A converter 22 shown in the OW unit 4 converts it into an analog signal and sends it to the telephone 23.

By doing this, only one OW unit is required for both A and B stations, and even if one of the lines becomes abnormal, the OW signal can be transmitted and received without any problem.

Next, the switching circuit 38 will be explained using FIG. 4. The optical terminal devices 27 to 29 constantly monitor whether optical signals are being received normally using detection circuits for detecting frame synchronization signal deviations, code errors, optical input interruptions, etc., and if an abnormality is detected, an alarm signal is relayed. is operated to close ALM contacts r1 ₁ to _{r1 3} . Signal lines from the ALM contacts r1 ₁ to r1 ₃ are connected to AND circuits 41 to 43 in the switching circuit 38. The signal lines from the ALM contacts r1 ₁ to _{r1 3} are at H level when normal, and are at L level when abnormal. Therefore, when the optical terminal equipment 27 to 29 are normal, only the OW signal via the optical terminal equipment 27 is sent to the D/A converter 39 of the OW unit via the AND circuit 41 and the OR circuit 44, and is converted into an analog signal. It is then sent to telephone 40. This is because the other AND circuits are blocked by the inverted signal of the normal signal via the NOT circuit 45.

Now, for example, if the optical terminal equipment 27 becomes abnormal, the ALM
The contact r1 ₁ is closed and the AND circuit 41 is closed. Therefore, in this case, the AND circuit 42 is opened by the inverted signal of the abnormal signal from the optical terminal device 27 and the normal signal from the own terminal station, and the OW signal via the optical terminal device 28 is connected to the AND circuit 42 or The signal is sent to the D/A converter 39 via the circuit 44, where it becomes an analog signal and is sent to the telephone 40. Further, the AND circuit 43 is blocked by a NOT circuit 46 with an inverted signal of the normal signal. That is, the switching circuit 38 selects one of the OW signals extracted from the normally received signals.
Send to OW unit.

As explained above, in the method of the present invention, both A station and B station,
By providing only one OW unit, the OW signal can be transmitted and received without any problem even if one of the circuits becomes abnormal, and although switching circuits 37 and 38 are required, the system is economical overall.

(g) Effects of the Invention As explained in detail above, according to the present invention, when transmitting an OW signal between stations having a plurality of terminal equipment that inserts an OW signal into the main signal and transmits it, each station can transmit an OW signal.
Since the OW unit can send and receive OW signals without any problem even if one of the transmission lines becomes abnormal, it has the effect of making OW signal transmission economical.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an optical fiber transmission system, Fig. 2 is a system diagram showing communication line transmission and reception between offices having a plurality of conventional optical terminal equipment, and Fig. 3 is an optical terminal equipment according to an embodiment of the present invention. A block diagram of a meeting line signal transmission/reception system between stations having multiple devices,
FIG. 4 is a block diagram mainly showing a circuit for selectively receiving one of the meeting line signals received from a normal transmission line according to an embodiment of the present invention. In the figure, 1, 2, 24 to 29 are optical terminal equipment, 3,
4, 30-35 are meeting line units, 5, 36
is an optical fiber cable, 6 and 12 are input interface circuits, 7 and 13 are code conversion circuits, and 8 and 14 are
9 and 15 are output interface circuits, 10 and 16 are code demodulation circuits, and 11 and 1 are electrical/optical conversion circuits.
7 is an optical/electric conversion circuit, 18 and 21 are analog/
Digital converters; 19, 22, and 39 are digital-to-analog converters; 20, 23, and 40 are telephones; 37 and 38 are switching circuits; 41 to 43 are AND circuits; 44 is an OR circuit; 45 and 46 are NOT circuits; r1 ₁ to _{r1 3} indicate contacts of alarm relays.

Claims (1)

[Claims] 1. In a configuration in which three or more sets of terminal station equipment are arranged in parallel to connect a main signal line that transmits high-speed main signals between two stations, each station receives telephone signals for meetings with the opposite station. One meeting line unit is provided to encode and transmit and receive the OW signal as an OW signal, and one switching circuit is provided for selecting the received OW signal.The OW signal from the meeting line unit is
This is a signal that is inserted into the high-speed main signal between all end station equipment and transmitted, and the switching circuit at the opposite station indicates the normality of the main signal line from the terminal station in the previous order, and the OW signal from that terminal station. and send it to the meeting line unit,
from other terminal stations with a normal main signal line.
This is done by blocking the OW signal and by a signal indicating a fault in the main signal line from the terminal station that was sending the OW signal to the meeting line unit, and a signal indicating that the main signal line of the next terminal station is normal. The OW signal from the terminal station in the next order is sent to the meeting line unit, and the OW signal from the other terminal station with a normal main signal line is sent.
A meeting line signal transmission system characterized by having a function of blocking OW signals.