JPS6087546A - Optical transmission system - Google Patents

Abstract

PURPOSE:To increase the number of terminal devices to be connected to an optical transmission line by using an optical branching device to form an optical transmission of a return path into plural optical transmission lines thereby decreasing the number of optical branching devices per one optical transmission line. CONSTITUTION:The ruturn optical transmission line is formed into two return optical transmission lines 33, 34 by using the optical branching device 35 and optical branching devices 21-30 are connected dividedly to the return optical transmission lines 33, 34. In transmitting light of 0dB from a U-turn point (b) with a loss of 5dB each branched into two directions by the optical branching device, a reception level of each receiver of optical data transmitters 1-10 is as shown in a B row. In comparison with conventional data as listed on a row A, the reception level on the row B is higher when 4 sets of the optical data terminal devices are used, 8 sets of optical data terminal devices are connected at a receivable enable level of -28dB and two sets more devices are increased than the conventional system.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to an optical bus network in which a large number of original data links are connected, and is capable of increasing the number of original data terminal devices connected to an optical transmission line. Regarding transmission methods.

(b) Technical background A data link is a pair of two data terminal devices controlled by a link protocol and a data line interconnecting each other, and is used to transfer data from a data transmitting device to a data receiving device. It is possible.

(C) Prior art and problems Figure 1 is a block diagram of a conventional U-shaped source data path network, Figure 2 is a block diagram of the ODB source from point A. A diagram showing the input level of the device is shown in FIG. 1.

In the figure, 1 to 10 are original data terminal devices, 11 to 20 are original couplers, 21 to 30 are optical branchers, 31 is an outgoing optical transmission line, and 3
2 indicates a return optical transmission line.

For example, in the case of communication between the original data terminal devices 5 and 6, when the transmitting device of the original data terminal device @5 sends data with the address of the original data terminal device 6 attached. , passes through the original coupler 15° 14.13, 12.11 and the outgoing optical transmission line 31, reaches point A, passes through the incoming optical transmission line 32 and the optical splitters 21 to 26, and reaches the optical splitter 26.
The signal is branched at , and input to the receiving device of the original data terminal device 6 . The original data terminal device 6 sends response data to this data from the transmitting device with the address of the optical data terminal device 5 attached. The transmitted data is branched at the optical branching device 25 via the same route as above and inputted to the receiving device of the original data terminal device 5. Communication between the data terminal devices of each party is performed as shown in C.

Assuming that the loss of the residual light splitters 21 to 30 is 3 db in the passing direction and 13 db in the branching direction, and that Qdb of light is transmitted from the U-shaped point A, the signal level of each party's data terminal device 1 decreases. In this case, if the receivable level is -28db, for example, only six original data terminal devices can be connected. First, the conventional system has the disadvantage that the number of connectable source data terminal devices is small.

(di) Purpose of the Invention In view of the above drawbacks, the purpose of the present invention is to provide an optical transmission system that can increase the number of original data terminal devices connected to an optical transmission line.

(e) Structure of the Invention In order to achieve the above-mentioned object, the present invention uses an optical branching device to form a plurality of optical transmission lines on the return path, and the receiving data terminal equipment of each party is connected to the plurality of optical transmission lines. The present invention is characterized in that the optical branching devices connected to the device are inserted in a distributed manner to reduce the number of optical branching devices on one original transmission line, thereby reducing optical attenuation.

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

FIG. 3 is a block diagram of a U-shaped optical data bus network according to an embodiment of the present invention.

Components in the figure that have the same functions as those in FIG. 1 are indicated by the same symbols.

33 and '34 are return optical transmission lines, and 35 is an optical branching device.

The difference between FIG. 3 and FIG. 1 is that the return optical transmission line is an optical splitter 35) and two return optical transmission lines 33° and 34, and the optical splitters 21 to 30 are connected to the return optical transmission line 33.゜34 points are distributed and connected.

The loss of splitting the source into two directions at the after-light splitter 35 is 5d each.
b, and if the source of Qdb is transmitted from the U-shaped point, the damage level of the receiving device of each source data terminal device 1 to IO will be as shown in line B of FIG. Comparing line B in Figure 2 and line A in Figure 2, the power in line B is that if the original data terminal device has 4 or more colors, the reception level will be high, □ Receivable level '&-28db. Then, the number of optical data terminal devices can be connected to 8G, which increases the number of optical data terminal devices by two compared to the case shown in FIG. Furthermore, the third
The figure shows a case where there are two optical transmission lines for the return route, but if the number of optical transmission lines is increased to 3 or 4 using an optical splitter, the original data terminal can be connected to more optical transmission lines. The number of devices can be increased.

(g) Effects of the Invention As explained in detail above, according to the present invention, the original attenuation caused by inserting an optical splitter can be reduced, so that more original data terminal devices can be connected to the optical transmission line.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional U-shaped optical data bus network, Fig. 2 shows the input level of the receiving device of each source data terminal device when QdbO source is transmitted from the U-shaped point, and Fig. 3 1 is a block diagram of a U-shaped optical data bus network according to an embodiment of the present invention; FIG. In the figure, 1 to 10 are optical data terminal devices, 11 to 20 are optical couplers, 21 to 30.35 are optical branchers, 31 is an outgoing optical transmission line, and 32 to 34 are incoming optical transmission lines.

Claims (1)

[Claims] In an original data bus network () work that connects a large number of original data links, the return optical transmission line is made into multiple optical transmission lines using a 1-way splitter, and a 6-way data terminal equipment is connected to the multiple optical transmission lines. An optical transmission system characterized by distributing and inserting optical splitters connected to receiving devices.