RU82505U1 - SINGLE-FIBER OPTICAL INTERFACE FOR NETWORK JOINTS OF DIGITAL ATE AND ASC - Google Patents

Abstract

A single-fiber optical interface for network interfaces of digital automatic telephone exchanges (ATS) and subscriber digital hubs (ACC), including a linear encoder, an adjustable modulator, a laser module, an optical receiver, a linear decoder, a clock selector, and the linear encoder has an input interface for information and the clock signals “Inf” and “cycle” towards the equipment of the network interface, and the output of the linear encoder is connected to one of the inputs of the adjustable modulator, the second input of which is connected n with the feedback output voltage of the laser module OS, and the output of the adjustable modulator is connected to the input of the laser module, while the output of the optical receiver is connected to the inputs of the linear decoder and the clock selector, the output of the clock selector is connected to the clock input of the linear decoder and output to the interface towards the equipment of the network interface with an external “clock” output, and the output of a linear decoder is also output to this interface with an external “Inf” output, characterized in that it contains a multiplex p wavelengths, the optical output of the transmitter being connected to the input of the wavelength multiplexer having a unidirectional bi-directional interface towards the line, and the output of the multiplexer being connected to the optical input of the receiver, while the laser modules on both sides of the line should have different wavelengths of 1.3 μm (1.55 μm), and the receivers should provide the required sensitivity threshold at the wavelengths emitted by the laser modules at the opposite end of the 1.55 μm (1.3 μm) line.

Description

The proposed utility model relates to telecommunication technologies and, in particular, to digital automatic telephone exchanges (ATS), subscriber digital hubs (ASC) and other telecommunication devices using optical interfaces.

On its basis, it is proposed to improve the optical interfaces of the network interface devices of digital telephone exchanges, ACCs and others, so that instead of the traditionally used two optical fibers, only one optical fiber is used for signal transmission in both directions, and thereby reduce the volume of linear structures used for the construction of optical access networks doubled. In addition, using the proposed utility model, it is possible to free up to half of the fibers in the optical cables of optical access networks already built and in operation in order to use these fibers to organize an overlay data network and provide subscribers with broadband Internet access on an ongoing basis .

The device KLT-2C, described in the book: Fiber-optic transmission systems and cables: Reference book / I.I. Grodnev, A.G. Muradyan, R.M. Sharafutdinov and others, was chosen as a prototype. - M .: Radio and communications, 1993 .-- 264 p.: Ill. On page 152 of this book, see fig. 7.10.

This device includes a PD board, a PR board, and a PC board, on which equipment that supports a dual-fiber optical interface, referred to in the indicated literature as “KLT-2C Kit”, is located.

This device is intended for the organization of a linear light guide path of a secondary digital transmission system for urban telephone networks. This equipment includes functional units that perform the following functions:

- conversion of the butt code into a linear code;

- control of the pump current and modulation of the radiation of a semiconductor laser;

- converting the electrical signal into an optical one, and inputting the optical signal into one of two optical fibers used for bi-directional transmission of optical fibers of an optical communication cable;

- receiving optical radiation from a second optical fiber, converting it into an electrical signal, amplifying, regenerating and decoding, as well as restoring the clock sequence of the received signal.

The disadvantage of this prototype device is that its fiber-optic linear termination (fiber-optic interface) involves the use of two optical fibers for transmitting signals in opposite directions.

The purpose of this utility model is to create such an optical interface for network interfaces of digital telephone exchanges, ACCs and other telecommunication devices, which instead of two fibers would have one fiber, and would ensure the transmission of information along this fiber in both directions.

To achieve this goal, it is proposed to use a single-fiber optical interface, supplemented by a wavelength multiplexer and using optical radiation transmitters at different wavelengths at opposite ends of a single-fiber optical line that fall into different transparency windows of the optical fiber (1.3 μm and 1.55 μm). In this case, the receivers must have satisfactory sensitivity thresholds in the used wavelength ranges. In this case, the wavelength multiplexer should have attenuation in the direction between the transmitter and the receiver of the interface located on each side of the line, at least the value at which the influence of the transmitter on “your” receiver would not trigger an alarm about the presence of a signal at the input of the receiver, and when a single-fiber line is broken, when the transmitters are working at both ends of the line, the “reception alarm” alarms (signal about the decrease in the power level at the receiver input below a predetermined threshold) should be activated.

On the basis of the proposed utility model, it will be possible to double save the fibers in optical communication cables (OX) on the basis of which linear structures of optical access networks are constructed using PBX and ACC with network interface devices that use this utility model.

In addition, the use of such a useful model in the reconstruction of already constructed access networks that used up to this point the network interface of the PBX and the ACC with traditional dual-fiber interfaces, will release up to half the fibers in the ACS, on the basis of which were built

linear structures of these networks. The released fibers can be used, for example, to organize Ethernet broadband optical paths using media converters. Such paths can be used on the backbone sections of access networks (connecting switches), for example, using ADSL technologies or laying cabling of category 5 cabling to the premises for permanent access of subscribers to the Internet.

Figure 1 shows the structure of one of the options for a single-fiber optical interface for devices of a network interface of a digital telephone exchange and an ACC, where:

1. linear encoder (LC);

2. adjustable modulator (RM);

3. laser module (LM);

4. wavelength multiplexer (MDV);

5. optical receiver (ODA);

6. linear decoder (LD);

7. Highlight Clock (VTCH).

The purpose of these components is as follows:

- a linear encoder (LC) 1 is designed to convert a binary signal from a network interface equipment or from another in the NRZ code to a signal encoded by a binary linear code (for example CMI), suitable for transmission via a fiber optic line;

- an adjustable modulator (PM) 2 is designed to control the average power emitted by the laser module (stabilization of optical power, light feedback), as well as to modulate the emitted optical signal by changing the pump current of the laser emitter according to the law of the transmitted signal;

- a laser module (LM) 3 is designed to convert an electrical signal into an optical signal with a given wavelength of optical radiation (in this case 1.3 μm or 1.55 μm), to control the power of optical radiation through a feedback photodiode, to provide the necessary temperature laser emitter mode, for inputting power into the optical fiber of the optical communication cable;

- wavelength multiplexer (MDV) 4 is designed to block the signal from LM 3 to OPR 5, to transmit a signal with a wavelength of LM 3-1.3 μm (1.55 μm) to the line, to transmit the signal from the line 1.55 μm (1.3 μm) in ODA 5;

- an optical receiver (OPR) 5 is needed to convert an optical signal coming from the line into an electrical signal encoded by a linear code;

- linear decoder 6 (LD) is needed to convert a signal encoded by a linear code into a signal encoded by the NRZ butt code;

- a clock selector (VTCH) 7 is designed to restore a clock signal at the receiving end of the line.

The main advantages of the proposed single-fiber optical interface

- Ability to build single-fiber optical lines.

- Saving optical fibers when building optical access networks based on network interface devices of digital telephone exchanges and agribusiness equipped with the proposed single-fiber interface.

- The release of optical fibers in communication cables during the reconstruction of already constructed access networks using the proposed single-fiber interface. The ability to use the released fibers, for example, to expand the subscriber capacity of the Internet with the possibility of a permanent connection.

Implementation of single-fiber optical interface nodes

All nodes of the proposed single-fiber interface with the exception of LM 3 are implemented in FSUE LONIIS. The proposed equipment uses LM 3 as domestic laser modules POM-664 (1.3 μm), POM-674 (1.55 μm) manufactured by TELAZ CJSC.

Linear encoder (LC) 1, as well as decoder (LD) 6, can be implemented both on microcircuits of medium degree of integration, for example, 74ALS series, and on VLSI

programmable logic. Adjustable modulator 3 can be implemented, for example, on chips of operational amplifiers and transistors, or can be performed as part of a transmitting optical module (POM).

The wavelength multiplexer (MDV) 4 can be built on the basis of WDM-multiplexers AMP 107824-1, 1300/1500. To provide the necessary attenuation of the influence of the optical signal from LM 3 on OPR 5, a cascade connection of two multiplexers of the indicated type on each side of the line is used.

Optical receiver OPr5 is implemented on the basis of domestic optical receiving modules PROM-367 manufactured by CJSC TELAZ or others, designed for the used range of transmission speeds and providing a satisfactory sensitivity threshold in the ranges of 1.3 μm and 1.5 μm. The clock isolator (VTCH) 7 is implemented on the basis of monolithic quartz filters of domestic production, at a central frequency equal to the bit rate for which the interface is designed. All nodes of the proposed optical interface have been tested as part of model automatic telephone exchanges and ATsK at the factory stands of FSUE LONIIS. The positive results of these tests indicate the operability of the proposed complex of technical solutions and its suitability for serial industrial production.

Claims (1)

A single-fiber optical interface for network interfaces of digital automatic telephone exchanges (ATS) and subscriber digital hubs (ACC), including a linear encoder, an adjustable modulator, a laser module, an optical receiver, a linear decoder, a clock selector, and the linear encoder has an input interface for information and the clock signals “Inf” and “cycle” towards the equipment of the network interface, and the output of the linear encoder is connected to one of the inputs of the adjustable modulator, the second input of which is connected n with the feedback output voltage of the laser module OS, and the output of the adjustable modulator is connected to the input of the laser module, while the output of the optical receiver is connected to the inputs of the linear decoder and the clock selector, the output of the clock selector is connected to the clock input of the linear decoder and output to the interface in the direction of the equipment of the network interface with an external “clock” output, and the output of a linear decoder is also output to this interface with an external “Inf” output, characterized in that it contains a multiplex p wavelengths, the optical output of the transmitter being connected to the input of the wavelength multiplexer having a unidirectional bi-directional interface towards the line, and the output of the multiplexer being connected to the optical input of the receiver, while the laser modules on both sides of the line should have different wavelengths of 1.3 μm (1.55 μm), and the receivers must provide the required sensitivity threshold at the wavelengths emitted by the laser modules at the opposite end of the 1.55 μm (1.3 μm) line.