JPH0622349B2 - Optical signal return method in U-shaped optical transmission line - Google Patents

Description

DETAILED DESCRIPTION [Overview] Carrier Sense Multiple Access / Collision with Collision Detection Function by Optical Signal
Detection (hereinafter referred to as CSMA / CD communication method), a small-scale system can be configured at low cost by adding a bidirectional loopback function to the optical repeater in order to reduce the system cost particularly in a small-scale configuration. It is the one.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an optical signal folding method of a U-shaped optical transmission line in a transmission system using a CSMA / CD communication system by an optical signal.

At this time, in terms of system cost, it is desirable that the system be capable of connecting and using more terminals with a smaller number of optical repeaters.

[Conventional technology]

FIG. 3 is a block diagram showing the configuration of a system using the conventional optical signal folding method.

FIG. 3 shows 15 optical couplers on the transmission side transmission line of the optical transmission line 10.
(5-1, ~, 5-15) are inserted, and 15 optical couplers (5-16, ~, 5-30) are also inserted in the receiving side transmission line. Then, the electric signal output from the terminal device (7-1, ..., 7-15) is converted into an electric / optical conversion unit (hereinafter referred to as E / E) in the optical transceiver (6-1, ..., 15).
It is converted to an optical signal by O) and added to the optical couplers (5-1, ..., 5-15) on the transmitting side.

On the other hand, in the optical coupler (5-16, ~, 5-30) on the receiving side, the optical signal transmitted through the optical transmission line 10 is branched, and the optical transceiver
The optical / electrical converter (hereinafter referred to as O / E) in (6-1, 6-, 6-15) converts the electric signal into an electric signal, and the terminal device (7
-1, ~, 7-15) is received.

Due to the transmission loss of the optical fiber of the optical transmission line 10 and the insertion loss of the optical coupler, the pulse waveform of the optical signal to be transmitted is deteriorated, and the error rate is prevented from increasing in the receiving terminal device. The optical repeater 3 ″ is inserted in.

In this case, a pair of O / E35 and E / O36 inserted in the transmitting side
It is assumed that 10 optical couplers (5-11, ~, 5-20) can be supported (the number of terminal devices is 5). Similarly, with the E / O37 and O / E38 inserted on the receiving side, 10 optical couplers (5-2
1, ~, 5-30) (10 terminal devices are supported).

In other words, one optical repeater 3 ″ supports 15 terminal devices.

Next, the operation of the system shown in FIG. 3 will be described.

For example, assume that the terminal device 7-1 desires to exchange signals with the terminal device 7-15. In this case, when the terminal device 7-1 detects that there is no received data from the optical transceiver 6-1, that is, that the optical transmission line 10 is empty, the terminal device 7 on the transmission side.
-1 outputs transmission data, and E / O of optical transceiver 6-1
Is converted into an optical signal by and is added to the optical transmission line 10 via the optical coupler 5-1. And with O / E35 of optical repeater 3 ″,
The pulse waveform of the optical signal is converted into a pulse waveform of an electric signal by, for example, a PIN photodiode, and after the waveform is shaped and amplified, it is converted into a pulse waveform of the optical signal again by the light emitting diode or the like in the E / O 36 and output. Then, it is returned to the reception side transmission line in the return section, branched by the optical coupler 5-16, converted into an electric signal by the O / E in the optical transceiver 6-15, and received by the terminal device 7-15.

When a signal is sent from the terminal device 7-15 to the terminal device 7-1, it is performed by following a path similar to the above path.

When receiving an optical signal, the optical coupler (5-16,
~, 5-30), any terminal device can receive it if desired.

[Problems to be solved by the invention]

However, in the above optical signal folding method, 1
The number of terminal devices that can be supported by one optical repeater is small, and in particular in a small-scale system, there has been a problem that the system cost rises.

[Means for solving problems]

The above-mentioned problem is, as shown in FIG. 1, two sets of optical transmission lines 1 and 2 in which the transmitting side and the receiving side are separated by a folding part,
Optical couplers 5-1, 5 -n for inserting or dropping optical signals into the optical transmission lines 1 and 2, and an optical coupler 5-1,
~, 5-n, an optical transceiver 6-having a function of converting an electric signal into an optical signal and converting an optical signal into an electric signal 6-
1, ..., 6-m and terminal devices 7-1, which are connected to the optical transceivers 6-1,-, 6-m, monitor the usage status of the optical transmission lines 1 and 2, and send and receive signals. , 7-m of the optical transmission system consisting of the optical transmission lines 1 and 2 are opposed to each other, and the optical signal of the optical transmission line 1 or 2 is amplified by the folding part of the optical transmission lines 1 and 2. A common optical repeater 3 is inserted into the transmission lines 1 and 2, and a logical sum circuit 4 for obtaining a logical sum of two inputs and outputting the logical sum is provided in the optical repeater 3, and This is solved by the optical signal folding method in the U-shaped optical transmission line of the present invention configured to output a signal to the receiving side of the optical transmission lines 1 and 2 via the logical sum circuit 4.

[Action]

In FIG. 1, for example, a signal output from the terminal device 7-1 is converted into an optical signal by the optical transceiver 6-1 and the optical coupler 5-1
Is transmitted to the transmission side of the optical transmission line 1 via. Then, the optical / electrical converter of the optical repeater 3 connected to the folded portion of the optical transmission line 1 converts the electric signal into an electric signal, which is input to the logical sum circuit 4. The output of the logical sum circuit 4 is transmitted to the receiving side of the optical transmission lines 1 and 2 via the electric / optical conversion unit of the optical repeater 3.

As a result, the other terminal device (for example, the terminal device 7-m of the optical transmission line 2) that desires to receive the signal receives this signal via the optical coupler 5-m + 1 and the optical transceiver 6-m.

〔Example〕

FIG. 2 is a block diagram showing the configuration of a system using the optical signal folding method according to the embodiment of the present invention.

The same reference numerals denote the same objects throughout the drawings.

In FIG. 2, the present invention is different from the conventional example in that the folded portions of the optical transmission lines 1'and 2'are made to face each other and an optical repeater 3'is inserted between the transmitting side and the receiving side. By providing the OR circuit 4 in the repeater 3 ', one optical repeater 3'combines two optical transmission lines 1'and 2'.

The operation will be described below.

For example, it is assumed that the terminal device 7-1 wishes to exchange signals with the terminal device 7-10 '. In this case, if the optical transmission line 2'is in use, the output of the logical sum circuit 4 provided in the optical repeater 3'is branched, and the terminal device is branched through the optical coupler 5-20 and the optical transceiver 6-1. In 7-1, it can be detected that the optical transmission line 2'is in use.

The optical transmission line 1'can be detected in the same manner.

In this way, after confirming that the optical transmission lines 1 ', 2'are vacant, the terminal device 7-1 outputs the transmission data and transmits the optical data via the optical transceiver 6-1 and the optical coupler 5-1. A signal is sent to the transmission line 1 ', converted into an electric signal by O / E31 in the optical repeater 3', and sent to the logical sum circuit 4. In the logical sum circuit 4, the input signal is branched to the optical transmission lines 1'and 2 ', and output. In this case, the E / O 34 converts it again into an optical signal, and the optical coupler 5'of the optical transmission line 2'is used. 11. It is sent to the terminal device 7-10 'via the optical transceiver 6-10'. Terminal device 7-10 ′ to 7-
The same applies when sending a signal to 1.

That is, the signal output from the terminal device 7-10 'is converted into an optical signal by the optical transceiver 6-10', and the optical signal is transmitted from the optical transmission line 2'to the optical repeater 3'and the logical sum circuit via the optical coupler 5-10. The optical transmission line 1'is provided as one output of the outputs branched via
From the optical coupler 5-20 and the optical transceiver 6-1 to the terminal device 7-1.

In this way, for example, communication is performed between the terminal devices 7-1 and 7-10 '.

As a result, in the case of this embodiment, one optical repeater 3'provides 20
One terminal device can be connected and used.

〔The invention's effect〕

As described above, according to the present invention, it is possible to increase the number of terminals that can be supported by the repeater, so that there is an effect of reducing the system cost.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention, FIG. 2 is a block diagram showing a configuration of a system using an optical signal folding method according to an embodiment of the present invention, and FIG. 3 is a system using a conventional optical signal folding method. 3 is a block diagram showing the configuration of FIG. In the figure, 1, 2, 1 ', 2', 10 are optical transmission lines, 3, 3 ', 3 "are optical repeaters, 31, 32 are optical / electrical converters (O / E), 33, 34 are electrical. / Optical converter (E / O), 4 is a logical sum circuit, 5-1, ~, 5-n are optical couplers, 6-1, ~, 6-m are optical transceivers, 7-1, ~, 7- m indicates a terminal device.

Claims (1)

[Claims] 1. A pair of optical transmission lines (1) and (2) separated from each other by a folded portion at a transmitting side and a receiving side, and an optical signal inserted into the optical transmission lines (1) and (2). Is connected to the optical coupler (5-1, ..., 5-n) for branching or inserting the optical signal, and the electrical signal is converted into an optical signal. An optical transceiver (6-1, ~, 6-m) having a function of converting an optical signal into an electrical signal, and an optical transmission line connected to the optical transceiver (6-1, ~, 6-m)
(1) and (2) of the optical transmission line (1) and (of the optical transmission system consisting of the terminal device (7-1, ~, 7-m) for transmitting and receiving signals and monitoring the use state The folded portions of 2) are opposed to each other, and the folded portions of the optical transmission lines (1) and (2) are connected to the optical transmission line (1) or (2).
A common optical repeater (3) is inserted into the optical transmission lines (1) and (2) for amplifying the optical signal of, and the logical sum of two inputs is obtained and output in the optical repeater (3). A logical sum circuit (4) is provided for the optical transmission line.
The signal on the transmission side of (1) or (2) is configured to be output to the reception side of the optical transmission lines (1) and (2) via the logical sum circuit (4). A method for returning an optical signal in a U-shaped optical transmission line.