JPS60172839A - Optical transmission system - Google Patents

Abstract

PURPOSE:To decrease the scale of a circuit and to reduce the deterioration of transmission by using the optical wavelength multiplex transmission technology, transmitting all signals at each terminal device or service unit while using a light source of different wavelength and separating the wavelength at a transmitter at the station side and a transmitter at the subscriber. CONSTITUTION:Electric signals from terminal devices 11-1n are converted into optical signals by electrooptic converting circuits 71-7n, the optical signals are coupled to an optical fiber 9' by an optical synthesizer and branching filter 8 through optical fibers 911-9n1 and transmitted. The optical signal through the optical fiber is extracted by the optical synthesizing and branching filter 8', converted into electric signals by an optoelectric converting circuit 10' and inputted to an intra-office transmitter or exchanges 131-13n . On the other hand, the signal outputted from the intra-office transmitter or the exchanges 131-13n is transmitted to the terminal device through the opposite path to the path above. Since the wavelength of the light source of the electroptic converting circuits 71-7n, 71'- 7n' is different entirely, the wavelength of the signals is synthesized or separated by the optical synthesizer and branching filter and transmitted through one optical fiber 9'.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an optical transmission system using optical wavelength division multiplexing transmission technology.

(Background Art) FIG. 1 shows the configuration of a transmission system using conventional optical wavelength division multiplexing transmission technology. This will be explained using FIG. 1.

The signals from the terminals 11 to 11 and the local area network 2 are passed through the electrical cables 31 to 37+ to the electrical interface circuits 4□ to 4+1, where they are processed and converted into a signal format that is easy to carry by the electrical multiplexing/demultiplexing circuit 5. , is combined with the signal from the monitoring control circuit 6, multiplexed by the electrical multiplexing/demultiplexing circuit 5, converted from the electrical signal to an optical signal by the electro-optic conversion circuit 7, and then sent to the optical fiber 9 by the optical multiplexer/demultiplexer 8. Optical signals are combined and transmitted. The optical signal after being transmitted through the optical fiber 9 is taken out by an optical multiplexer/demultiplexer 8', converted into an electrical signal by an opto-electric conversion circuit 10', and sent to a subscriber by an electrical multiplexing/demultiplexing circuit 5'. Electrical multiplexing/demultiplexing circuit 5 of side transmission device 11
On the contrary, the signals are separated into signals from each terminal 1 to 1 and the local area network 2 or into signals that can be processed by an exchange, and further, the respective signals are outputted from the station-side transmission device 12.

This signal undergoes signal format conversion in the electrical interface circuits 1 to 4, and is transmitted to the required exchanges or in-office transmission devices 13, to 137 via the 3□' to 3-core electrical cables. On the other hand, in-office transmission equipment or exchanges 131 to 13n+1
The signal input from the terminal is transmitted to the terminal by following the reverse route to that described above. Here, since the wavelengths of the light sources of the electro-optical conversion circuits 7 and 7' are different, the two wavelengths are combined and separated by an optical multiplexer/demultiplexer 8.8' and transmitted through a single optical fiber 9. There is.

FIG. 2 shows another configuration of a transmission system using conventional optical wavelength division multiplexing transmission technology. The basic operation is the same, but in FIG. 2, the electrical interface circuit 4 of FIG.
Electrical-optical/optical-electrical conversion circuit 1 in place of I+41' to 4I□
4,~14n+1,14,'~14I.

14,'~147:+14fi~14mu1, the subscriber side transmission device 11 and the terminal 11~1? The optical fibers 9□-- and l191'-971' are used to connect between the local area network 2 and the station-side transmission equipment 12 and the local transmission equipment or exchanges 131-13n+1. This is because electric cables cannot transmit long-distance unrepaired signals if the band of signals transmitted between them is wide, the transmission loss increases in high frequency bands, so cable equalization is required, and external electrical system noise It is used to avoid contamination.

FIG. 3 shows an example of the analog signal multiplexing format executed by the electrical multiplexing/demultiplexing circuits 5, 5' in the configuration example shown in FIGS. 1 and 2. From one terminal 1□, a video signal 16 and an audio signal 17. ．． 172 and starting, stopping the terminal,
A narrowband signal 181 necessary for selecting a channel is
The other terminal 1fL outputs a narrowband signal 18□ such as a telephone signal or a fax signal. The audio signals 17□, 17□ are multiplexed into the video signal 16 by FM modulation, and the narrowband signals 18□, 18□ are multiplexed into the video signal 16 by, for example, FSX or PSK modulation in an electrical multiplexing/demultiplexing circuit 5. On the other hand, the electrical multiplexing/demultiplexing circuit 5' of the station-side transmission device 12 performs reverse separation.

FIG. 4 shows another example of the analog signal multiplexing format executed by the electrical multiplexing/demultiplexing circuits 5, 5'. one terminal 1
From 1, there is a video signal 16 and an audio signal 17□.

17° and a narrowband signal 181, and from another terminal 12, a video signal 16' and an audio signal 17. ', 17□' and a narrowband signal 18□', and a narrowband signal 182 is output from another terminal 13. Among them, video signal 16.16' audio signal 17. ,17□,17□′,
17□' is frequency multiplexed by multiplexing similar to that shown in FIG. These multiplexed signals are FM-modulated onto separate carrier waves, and are further FM-modulated into terminals 1. ．． All of the narrowband signals 18, 18□' and 18□ outputted from 12.13 are frequency-multiplexed with two FM-modulated signals, for example, by Fsx modulation or PSK modulation.

The multiplexed signals shown in FIGS. 3 and 4 are converted into optical signals by the electro-optical conversion circuit 7 and transmitted through the optical fiber 9. Also, the reverse demultiplexing is performed in the electrical multiplexing/demultiplexing circuit 5'. In each example, an example of multiplexing of analog signals has been described, but in the case of digital signals as well, time division multiplexing or time division demultiplexing is performed in electrical multiplexing and demultiplexing circuits 5 and 5'.

In this configuration, signals coming from multiple terminals are converted into one electrical signal by frequency multiplexing or time division multiplexing, and converted into an optical signal by one electro-optical conversion circuit, so fewer light sources are used. However, the station side transmission device 1
2. The subscriber-side transmission device 11 must include an electrical multiplexing/demultiplexing circuit 5,
5' is required, the transmission quality deteriorates because the subscriber side transmission device 11 and the terminal or the station side transmission device 12 and the local transmission device or exchange are connected by the electric cable 3, and there is no need for relayless transmission over long distances. In order to solve these problems, an optical cable 9□ is used instead of the electric cable 3 as shown in FIG. 2.

When 9.7-9A is used, an electro-optical/optical-electrical conversion circuit is necessarily required, resulting in problems such as an increase in circuit scale and an increase in price.

(Problems to be solved by the invention) In order to eliminate these drawbacks, the present invention uses optical wavelength division multiplexing transmission technology to transmit all signals for each terminal or service using light sources with different wavelengths, and to transmit the signals at the station side. The equipment and subscriber side transmission equipment separate these wavelengths,
The optical signal is transmitted directly to a terminal and an intra-office transmission device or exchange, and optical-electrical conversion or electro-optical conversion is performed there, and will be described in detail below with reference to the drawings.

(Structure and operation of the invention) FIG. 5 shows an embodiment described in claim 1. Signals from the terminals 11 to 11 are converted into optical signals by electro-optical conversion circuits 71 to 7n, and then sent to optical fibers 9□, to 9. r
The optical signal is coupled to an optical fiber 9 by an optical multiplexer/demultiplexer 8 through L1 and transmitted. The optical signal transmitted through the optical fiber is extracted by the optical multiplexer/demultiplexer 81, converted into an electrical signal by the opto-electric conversion circuit 10', and inputted to the local transmission equipment or exchanges 13□ to 13n.

On the other hand, the signals output from the intra-office transmission devices or exchanges 13□ to 13n are transmitted to the terminals along the reverse route to that described above. Here, the electro-optical conversion circuits 7□ to 7n.

7□′〜7? Since the wavelengths of the light sources I' are all different, the wavelengths are combined and separated using an optical multiplexer/demultiplexer and transmitted through a single optical fiber 9. In this configuration, the subscriber-side transmission equipment is divided into 11 and 11□~1 beam, and these are connected by optical fibers without photoelectrical and electro-optic conversion. 11. can be placed near the terminal or inside the terminal, the electrical cables 3□ to 3n+1 shown in FIG. Since the signals to the terminal are carried on optical signals of different wavelengths, the system has features such as eliminating the need for electrical multiplexing and demultiplexing. Furthermore, for the configuration shown in FIG.
44-+-+ and optical fibers 9□ to 9n+1 are not required, and the electrical multiplexing/demultiplexing circuit 5 is not required.

FIG. 6 shows an embodiment described in claim 2. Since the basic operation is the same as that shown in FIG. 5, only the different points will be described.

FIG. 6 shows the subscriber side transmission device 11. The optical multiplexer/demultiplexer 8, ~8n is inserted into ~11n, and the optical signals with different wavelengths carrying the uplink and downlink signals of the terminals 11~ln are wavelength-multiplexed, so the subscriber side transmission equipment 11 and 11. ~1
1n can be connected by one optical fiber 91 to 9n. The features of this configuration are similar to those in FIG. Station side transmission device 1 in both configurations shown in FIGS. 5 and 6
2, 12. ~12n is similar to the subscriber side, so the effect is also the same.

In Fig. 7, the usage diagram for the configuration of Fig. 5 and Fig. 6 is shown in Fig. 6.
Corresponds to the diagram. In FIG. 7(α), two optical fiber sets 91□ and 91□ to 9n1 and 9n□, which connect subscriber-side optical transmission equipment 11 and 111 to 11n, each have a different wavelength. Optical signal λ1. ~ transport, and λ1r to λnr are transmitted to realize bidirectional transmission. In FIG. 7(b), subscriber side transmission equipment 11 and 11□~1
1. Optical signals λ1° and λ1r to λ7 .
and λnr are wavelength-multiplexed to achieve bidirectional transmission.

FIG. 8 shows the configuration examples shown in FIG. 5 and FIG. 7. This is an example of an analog signal multiplexing format that is implemented in the system.

From one terminal 11, a video signal 16 and an audio signal 171,
17□ and narrowband signal 18. However, the baseband,
The signals are multiplexed by FM modulation, FSK modulation, or PSK modulation and converted into an optical signal of one wavelength. From other terminal nodes, narrowband signals 18□ are transmitted to the baseband as shown by the solid line or 1. FM modulation, FSX modulation, A
The signal is M-modulated and PSK-modulated, converted into an optical signal of a different wavelength from that used by the terminal 11, and transmitted.

Figure 9 is an example of a multiplexing format different from that shown in Figure 8, and corresponds to Figure 4, which shows the configuration of a multiplexing format in a conventional configuration. The signals are multiplexed for each terminal, converted into optical signals with different wavelengths, and transmitted.

In Figures 8 and 9, we have described the case of frequency multiplexing analog signals, but in the case of digital signals, all signals coming from each terminal are similarly time-division multiplexed to convert them into optical signals with different wavelengths. and transmitted.

In addition, in FIGS. 5 and 6, the station-side transmission device 12□
12n can be installed in completely different locations from each other or from the station-side transmission device 12. This also applies to the subscriber side transmission devices 11, 11□ to 11n.

(Effects of the Invention) As explained above, according to the present invention, the circuit scale of the device is reduced, there is less deterioration in transmission quality6, and the cable is thinner and the number of fibers is reduced, making in-home wiring simpler. In addition, since signals can be added and dropped at the optical signal point, there are advantages such as a degree of freedom in network configuration, and it can be applied to subscriber-based optical transmission systems.

[Brief explanation of drawings]

Figure 1 is a diagram showing a configuration example of a conventional optical transmission system, Figure 2 is a diagram showing another configuration example of a conventional optical transmission system, and Figure 3 is a diagram showing an example of a signal multiplexing configuration in a conventional optical transmission system. FIG. 4 is a diagram showing another configuration example of signal multiplexing in a conventional optical transmission system. FIG. 5 is a diagram showing a configuration example of an optical transmission system according to the present invention. FIG. 7 is a diagram showing an example of how wavelengths are used according to the present invention. FIG. 8 is a diagram showing an example of a signal multiplexing configuration according to the present invention. FIG. 9 is a diagram showing an example of a signal multiplexing configuration according to the present invention. FIG. 7 is a diagram showing another configuration example of signal multiplexing. 11~Tamaha terminal, 2 is local area network, 3
1-3? L+I + 31""" 奥+1 is an electric cable, 41~4n+1+4,'~4I+1 are electric interface circuits, 5, 5' are electric multiplexing/demultiplexing circuits, 6,6
' is a monitoring control circuit, 7, 71 is an electro-optical conversion circuit, 8, 8
' is an optical multiplexer/demultiplexer, 9.9□~gn, g11-g/ are optical fibers (, 10, 10' are opto-electrical converters, 11 is a subscriber side transmission device, 12 is a central office side transmission device, 13. ~13n+,
is an in-office transmission device or switch, 14□~14n+1+1
4□/~14i, 14□#~1461゜147'~1v
, 1 is an electro-optical/optical-electric conversion circuit, 16.16' is a video signal, 17. , 17. □, 171', 17゜l are audio signals, 18□, 18□, 18. ' is a narrowband signal. Patent Applicant Nippon Telegraph and Telephone Public Corporation Patent Application Agent Mu Heng "Yama + Kichi - Book 7 fO 1st Qin 7 (b) Figure Bottom 8 Figure" - 11 Uwo Yupsi! 5゜

Claims (1)

[Claims] (1) After converting multiple electrical signals of the same type or different types necessary for providing multiple terminals or multiple services into optical signals of different wavelengths, they are combined or optical signals of different wavelengths are converted into optical signals of different wavelengths. After separating the optical signals into electrical signals, the optical signals are converted into electrical signals, and the plurality of terminals or the plurality of services are transmitted in one direction, two directions, or a combination thereof using at least one optical fiber. All electrical signals transmitted in the same direction among the electrical signals necessary for providing the service are classified and multiplexed for each terminal or service, and each multiplexed electrical signal is converted into an optical signal with a different wavelength. At the same time, the part that combines and separates optical signals of different wavelengths, the part that converts electrical signals to optical signals, and the part that converts optical signals to electrical signals are connected using separate optical fibers. An optical transmission method characterized by (2. In the optical transmission system described in claim 1, when bidirectionally transmitting electrical signals necessary for providing terminals or services, optical signals consisting of different wavelengths and lengths are combined and separated. A part that combines and separates two optical signals with mutually different wavelengths for bidirectional transmission, and a multiplexing part of multiplexed optical signals in which the two optical signals with mutually different wavelengths are multiplexed. An optical transmission system characterized by dividing an optical signal into parts to be combined and separated, and connecting each part with at least one optical fiber.