JPS6133030A - Repeating branch device for optical fiber transmission system - Google Patents

Abstract

PURPOSE:To attain a repeating branch device which is capable of long-distance transmission via an optical fiber by converting an optical signal into an electric signal to branch the electric signal into a desired number of signals and converting the branched electric signals into optical signals again for transmission. CONSTITUTION:The optical signal sent from a control station MS via an optical cable is supplied to terminals A1 and A2 of a repeating branch device RD and converted into the electric signals by optical/electric O/E converters 10a and 10b respectively. The electric signal is branched toward a slave station LS via the device RD of the next stage and a switch 20. Then the electric signal is converted again into the optical signal by E/O converters 11a and 11b in the direction of the RD and transmitted to an optical cable via terminals B1 and B2. While the electric signal is converted into the optical signal by E/O converters 11e-11h in the direction of an LS and transmitted to LS1-8 via terminals X1-X8 and the optical cable. The optical signals sent from an RD of the next stage and the LS are converted into electric signals by O/E converters 10c and 10d and 10e-10h via terminals C1 and C2 and Y1-Y8. These electric signals are converted again into optical signals by E/O converters 11c and 11d and sent to the MS through terminals D1 and D2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a relay branching device for an optical fiber transmission system, and particularly to a relay branching device for an optical fiber transmission system that branches optical fibers without reducing the transmission level of light. Regarding a branching device.

[Conventional technology and problems] The circuit configuration methods of data transmission systems can be classified into 1-bodies: bus type (branching type), star type (switching type), and ring type (routine 16 type). are categorized. In a data transmission system using a twisted pair cable or a coaxial cable as a transmission medium, one of the three types of circuit configurations mentioned in Section 41 above is adopted depending on the content and scale of the system. However, compared to twisted pair cables and coaxial cables, Qeit! has superior MS-free properties and transmission capacity. In a data transmission system that uses optical fiber as a transmission medium, where t is right, it is essentially difficult to adopt a bus-type data transmission system arm because light is used as a data carrier wave, and a ring-type or A star type transmission system is mainly used.

FIG. 2 is a diagram showing the configuration of a bus-type optical data transmission system using a conventional branching device. However, here we consider unidirectional communication. In FIG. 2, data transmission is from a transmitter 1 to a receiver 3a via a branching device 2 with a branching ratio of 1:1.
, 311.

Between receiver 1 and branch 2 and between branch 2 and receiver 3a
, 3b is used as a data transmission medium. Now, set the optical transmission level of transmitter 1 to -17d13m.
, reception l13a, 3b optical transmission 1 novel - 27dr
3 m, the input loss of the splitter 2 is -3 dB, and the optical fiber loss (attenuation mark) is 2.5 dB/Inn. These days,
) from the transmitter 1 to the receiver ll3a, 31), since the light is split 1:1 by the splitter 2, the distance is >”A (R
The level is reduced by about 3 dB, which is large -5 = (-17-(27>-3-31/2.5-1.6k
In! - Become. Therefore, when the conventional branching device 2 is used, long-distance transmission becomes impossible. Furthermore, if more receivers are installed, the transmission level from the branch to the receiver decreases in proportion to the number of receivers, so the distance over which data can be transmitted from the transmitter to the receiver becomes even shorter.

[Summary of the Invention] An object of the present invention is to provide a relay branching device that eliminates the drawbacks of the conventional branching device described above and enables a communication system using optical fibers capable of long-distance data transmission. be.

In summary, this invention is a relay branching device that converts a given optical signal into an electrical signal, branches the signal as many times as necessary in the electrical signal state, and after branching, converts it back into an optical signal and transmits it. .

The objects and other objects and features of the present invention will become more apparent from the detailed description given below in conjunction with the drawings.

[Embodiment of the Invention] FIG. 3 is a configuration diagram of a bus-type two-way communication system to which a relay branching device is applied, which is an embodiment of the present invention. In FIG. 3, a mask station (control station, hereinafter referred to as MS) 5 and a local station (dependent station, hereinafter referred to as L) are shown.
S) 78 to 71) are relay branching devices (hereinafter referred to as RD).
and mark 'l'> 6a.

6b and 6c form a bus type communication system.

Each of RD6a, 6t) and 6c has eight 1s7a~
71] is connected. Also M S 5 and l-S 7 a
-7b, bidirectional communication is performed using a polling selection method. Also, between MS5 and RI) 6a, between RD6a and RD6b, and between RD6t) and RD6
Data is transmitted between 4 C and 4 C using 4-core optical fiber cables. Further, data is transmitted between the RDs 6a, 6b, ('ic and the respective subordinate l-37a to 71) using a two-core optical fiber cable 4d.

FIG. 1 is a diagram showing the configuration of a relay branching device that is an embodiment of the present invention. In Figure 1, a relay branching device (RD
) is divided into a sending loop and a receiving loop.

The transmission loop is further divided into a trunk system loop (MS-relay branching device-relay branching device loop) and a dependent station loop (relay branching device-dependent station). First, the main line loop is the receiving terminal △3. Δ, an optical-to-electrical converter (hereinafter referred to as 0/]3 converter '1) 10a that converts an optical signal from the MS5 or any of the preceding relay/branching devices 5a, 6b, and 6C into an electrical signal; , 10b, and an electro-optical converter (hereinafter referred to as E10) that receives this electrical signal and performs electro-optical conversion to transmit the optical signal from the transmission terminal B+, [32 to the next stage relay/branch device (61) or 6C). Converter and description 1) 11a, 11
It consists of b. The dependent station loop is composed of an O/E converter 10a, a 10br converter 7j, and E10 converters 110 to 1111 that convert an electrical signal into an optical signal and transmit it to each dependent station 81 to LS8. This dependent station loop selects a normal signal from among the signals given from the O/E converters 10a and 10b and sends it to the E10 converter 11e.
A selection switch 20 is provided to select h. The selection switch 20 receives the signals from the O/E converters 10a and 10b, and disconnects the optical signal carrier and disconnects the O/F converters 10a and 10b.
Detector (K1) 1 that always detects high level output of 0b
Switching is controlled by 2.

Next, consider the reception loop divided into two loops: the trunk system and the dependent station system. The trunk system loop includes an O/E converter 10c that converts optical signals given from the subsequent relay/branch device to the receiving terminals C1 and C2 into electrical signals.

10d, and an O/E converter 10c, an E10 converter 11c that receives the signal from 10d and converts it into an optical signal.

11d. This loop is provided with switches 21a and 21b that conduct or cut off this path depending on the output state of the O/E converters 10c and 10d. The switches 21a and 21b are controlled by the 0/E converters 10c and 1
An output constant high level detector (K2) 13a that detects the output state of 0d and turns off the switches 21a and 21b only when the output state is always high level.
, 13b.

On the other hand, the dependent station loop includes O/F converters 108 to 10h that convert optical signals received from the dependent stations L S 1 to 1-88 (tji terminal -Y8) into electrical signals, and O/E
It is composed of E10 converters 11C and 11d that convert electrical signals from converters 10e to 10h into optical signals. This slave station loop has a detector (K2) as well as the main line loop.
Switches 21c each controlled by 13c to 13f
−21f h<provided.

Additionally, a monitoring device is provided which has a function of monitoring the status of the IC% detectors 12.13c-131 and transmitting the status to the MS5. This monitoring device has a receiving terminal Δ,. A normal signal among the signals given to A2 is input, and the detector 12.13
A signal representing the state of c~13[ is sent to the E10 converter 11C,
Serial input/output interface (810
) 30 and a central processing unit (CPU) 3 that processes information.
1, and an input/output interface (Ilo) '32 that inputs signals indicating the status of the detector 12, 13G and 13f. This monitoring device has a detector (K2) 139
and switch 21 (l) are provided to prevent the transmission of information that could result in a malfunction of the monitoring device itself.The state of this switch detector (K2) 13() is also monitored by the monitoring device, so 81030 to E10 converter 11c,
If no signal is output to 11d, this indicates that the monitoring device itself is out of order.

Here, O/E installed in the trunk system (both transmission and reception)
The reason why the converters 10a to 10d, the E101 converters 11a to 11d, and the optical fiber/IC are duplicated is to cope with malfunction of one optical fiber or one E10 converter or 0/E converter. This is to provide a backup function that can be used.

The operation of data transmission using this relay/branch device will be described below.

First, let's talk about transmission. M for receiving terminals A, A2
An optical signal from S5 or the preceding relay/distribution device (RD) is given. This optical signal is transmitted to 0/F converters 10a and 10b.
is converted into an electrical signal by The signals converted into electrical signals are again converted into optical signals by the E10 converters 11a and 11b, and transmitted from the transmission terminals [3, , 82 to the next stage relay/branch device. During normal operation, receiving terminal A1. The same signal is applied to A2, and the same signal is output and transmitted from the transmission terminals B+ and Bz. On the other hand, if optical signals are input to the receiving terminals Δ1 and A2, are carriers disconnected?) or the O/E converter 10a.

A detector (K1) 12 detects whether the output of the output terminal 10b is always at a high level.

The switch 20 is controlled by the detector 12, and any normal signal is selected and applied to the 81030 and the 10 converters 11e to 11h.If both are normal, one of the signals (predetermined Furthermore, if both O/E converters 10a and 10b are abnormal, communication becomes impossible (addressing of dependent stations is impossible). The electrical signals given to the E10 converters 11e to 111) are converted to optical signals here and sent to the transmission terminals X, to x8.
is given to each subordinate station from each of them.

Next, let's talk about reception.

Optical signals are applied to the receiving terminals CI and C2 from the next-stage relay/branch device. This optical signal is transmitted to O/E converters 10C and 10d.
is converted into an electrical signal by
It is sent to the lt converters 11G and 11d.

At this time, if the output level of the 0/E converters 10G and 10++ is always high, all communication will be impossible (
The communication method is a polling selection method), and the states of the O/E converters 10a and 10b are constantly monitored by high level detectors (K2) 13a and 13b. O/E converter 1
When the outputs of 0a and 10b are always at high level, the detectors (K2) 13a and 13b detect the corresponding switch 2.
1a or switch 211) enters the cutoff state, and the circuit is cut off. Also, dependent station 1. ,, the optical signals given from 81 to l-88 to each receiving terminal Y, to Y8 are O, /E.
Each is converted into an electric signal by converters 10e to 10h,
Normally, the signal is sent to the E10 converters 11C to 11d. If at least one output of the O/E converters 130 to 13f is always at a high level, all communication will be impossible, so a constant high level detector (K2) 13cm13f provided in each circuit O/E converter 1
The output status from 0t3 to 10f is monitored. Detector (K2
) 130 to 13f detects a constant high level output, the corresponding detector (K2) 130 to 13f turns one of the corresponding switches 210 to 21f into a cutoff state, and the circuit is cut off.

Furthermore, the detector (K1) 12 and the detector (K12) 1
The status of 3a to 13f is the input/output interface of the monitoring device: [
The signal is applied to the chair (Ilo) 32, processed by the CPU 31, and transmitted to each detector (K1) 12 and the detector (K2).
The electrical signals corresponding to the states of 13a to 13f are 5I030.
The signal is then applied to E10 converters 11c and 11d. At this time, if the monitoring device itself is malfunctioning, the detector (K2
) 13 (+ causes switch 21 (+ to be cut off and the monitoring
No monitoring signal is output from the pA device. The electrical signals given to the E10 converters 11c and 11d are converted into optical signals and sent to the transmission terminal7. It is transmitted from D2 to MS5 or the preceding relay/distribution device @, (RD). As described above, communication is performed between the MS 5 and the dependent station selected by the MS 5 (the relay/branch device serves as a dependent station).

In the above embodiment, the number of dependent stations belonging to one relay branching device is eight, but it goes without saying that it is not necessary to limit the number to eight.

Also, as shown by the broken line in Figure 1, the connection method is not one relay branching device to one relay branching device, but one relay branching device to one relay branching device.
The same effects as in the above embodiment can be obtained even if one relay branching device is configured to be a plurality of relay branching devices.

Further, in the first embodiment, a bidirectional bus type (multi-drop type) communication method is explained, but the same effects as in the above embodiment can be obtained even if other communication methods such as a unidirectional communication method are used. It will be done.

[Effects of the Invention] As described above, the present invention has a configuration in which an optical data signal is once converted into an electrical signal, branched into as many signal lines as necessary, and then converted back into an optical signal and transmitted. Therefore, unlike conventional branching devices, there is no loss of optical signals due to relay branching devices, and long-distance data communication becomes possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a relay branching device that is an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of a conventional communication circuit. FIG. 3 is a circuit diagram of a bidirectional bus type communication system according to an embodiment of the present invention. In the figure, 4G is a 4-core optical fiber, 4 (1 is a 2-core optical fiber, 5 is a master station 1 (control station), 6
a, 6b, 6-c are relay branch 1 straddle (RD), 7
a, 7b are dependent stations (L, S), 10a to 10h are optical to electrical converters, 11a to 11h are electrical to optical converters, 1
2 is a carrier disconnection and output constant high level detector, 13
a~130 is an output constant high level detector, 20.21a
-21o is a switch, 30 is 5IO131 is CPLJ,
32 is Ilo. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (6)

[Claims] (1) A relay branching device for an optical fiber transmission system that receives an optical signal transmitted via an optical fiber transmission line, branches the optical signal into at least two, and transmits the optical signal to two or more dependent stations. , first optical-to-electrical converting means for converting the optical signal into an electrical signal; and receiving the electrical signal converted by the first optical-to-electrical converting means and converting it into an optical signal, and for each of the dependent stations. and first electrical-to-optical converting means connected in parallel to each other. (2) The relay/branch device is a relay/branch device for a bidirectional optical communication system between a control station and a plurality of dependent stations, and converts optical signals transmitted from each of the plurality of dependent stations into electrical signals. second optical-to-electrical converting means connected in parallel with each other, and a second electrical converter for receiving each electrical signal converted by each of the second optical-to-electrical converting means and converting it into an optical signal. - optical conversion means, and transmits the optical signal converted by the second electrical-to-optical conversion means to the control station via an optical fiber transmission line. System relay branch device. (3) The transmission path between the control station and the relay branching device is double-wired, a plurality of the first optical-to-electrical conversion means are provided, and the plurality of first optical-to-electrical conversion means first detection means for detecting interruption of the optical signal applied to each of the means and the output level of each of the plurality of first optical-to-electrical conversion means; and the plurality of first optical-to-electrical conversion means. and a first selection means for selectively conducting the outputs of the plurality of first light-to-electric conversion means, in response to the output of the first detection means, the first selection means selects the outputs of the plurality of first optical-to-electrical conversion means. A repeating/branching device for an optical fiber transmission system according to claim 1. (4) Each of the second optical-to-electrical conversion means includes: a second detection means for detecting interruption of the applied optical signal and the output level of the second optical-to-electrical conversion means itself; cutoff means for conducting or cutting off the output path of the light-to-electrical conversion means in response to the output signal of the second detection means; 4. A repeating/branching device for an optical fiber transmission system according to claim 2 or 3, which enters a cutoff state when the output level of the converting means is always at a high level. (5) The relay/branch device itself is one of the dependent stations, and transmits the output states of the first and second optical-to-electric conversion means detected by the first and second detection means to the control station. A relay branching device for an optical fiber transmission system according to any one of claims 2 to 4. (6) A relay branch for an optical fiber transmission system according to any one of claims 1 to 5, wherein the signal transmission/reception path between the control station and the relay branch device is duplicated. Device.