An Experimental 560 Mbits/s Repeater with Integrated Circuits

The bandwidth penalty of digital systems is very obvious in the case of transmission over coaxial cables because of the exponential increse of cable attenuation with square root of frequency. From capacity point of view, it is only at very high information rates (> 500 Mbit/s typically) that a digital system might be competitive with an analog system, because the disadvantage of noise accumulation in an analog system ultimately cancels the bandwidth penalty of the digital system. In addition, it is, however, difficult to realize common functions, such as amplification, equalization, regeneration, clock extraction, etc. with electronic components having a frequency range comparable to the frequency range of the information signal, which extends from zero frequency to the microwave range. Besides, the complexity of a regenerative repeater should be kept to a minimum for reliability reasons. It is shown in the paper that with present-day technology a 560 Mbit/s repeater can be constructed, operating in sections of 1.5 km coaxial cable (2.6/9.5 mm). Also, we demonstrate that new technologies exist which may lead to repeaters with a high degree of monolithic integration, even at such a speed, which is important from the reliability viewpoint. The constructed and described repeater is characterized by unconventional and economic design of amplifier/equalizer and clock extractor and by monolithically integrated decision circuits.     

Transmission experiments through 101 km and 84 km of single-mode fibre at 274 Mbit/s and 420 Mbit/s

Four transmission experiments through low-loss single-mode optical fibre at 1.3 ?m have been performed at 274 Mbit/s and 420 Mbit/s with different objectives. The first demonstrates transmission through 101 km of single-mode fibre at 274 Mbit/s with negligible dispersion penalty. The second experiment at 274 Mbit/s and 84 km uses only components suitable for use in an undersea cable system. Two additional experiments, both at 420 Mbit/s, accomplish a bitrate × distance product of 35 GHzkm with 84 km of fibre and show no dispersion penalty with 63 km and 2.4 ps/km nm dispersion.     

An Experimental 800 Mbit/s Four-Level Repeater Compatible with the 60 MHz Analog System

The design and performance of an experimental 800 Mbit/s repeater for four-level digital transmission over a coaxial cable is described in this paper. The 800 Mbit/s digital system exceeds the 60 MHz analog system, both in capacity and in economy. The repeater is designed to operate in repeater housings located at 1.6 km maximum spacing to be compatible with the 60 MHz analog sytsem. A nonredundant four-level line code has been employed, using a newly developed quantized feedback dc restoration technique. The most important item in realizing the high-speed multilevel repeater is the reduction of intersymbol interference. A simple quantized feedback scheme and an adjustable three-tap transversal equalizer have been used to compensate for intersymbol interference. The experimental repeater has been tested for 1.1-1.7 km repeater spacings using 2.6/9.5 mm coaxial cable. The results show that an 800 Mbit/s repeater with 1.6 km maximum repeater spacing is feasible.     

Optical Fiber Transmission System Demonstration Over 32 km with Repeaters Data Rate Transparent Up to 2.3 Mbits/s

An initial optical fiber transmission system under development for Army long haul tactical communications is described and evaluated. The system interfaces with the 2.304 Mbit/s data input and output of an Army inventory multiplexer and its orderwire. The system includes transmitter and receiver end terminals, three data rate transparent repeaters, 8 km of graded index optical fiber, plus three optical attenuators and various optical connectors for simulating transmission up to 32 km. Long repeater spacing is achieved using low loss fiber, semiconductor lasers stabilized using optical feedback, and avalanche photodiodes. The system met all of the specified requirements and shows that optical fiber transmission systems have excellent prospects of meeting full military specifications. The versatility of data rate transparent repeaters is achievable even for transmission up to the 64 km distance desired for Army long haul tactical communications.     

A Digital Hybrid Transmission System for 280 Mbits/s and 560 Mbits/s

This paper presents the development of repeaters and line equipment for an experimental digital long-haul transmission system using coaxial cable. A comparison, of different types of digital transmission systems indicates that the digital repeater hybrid system with binary transmission code is the most desirable. This development has resulted in digital pulse reshaping repeaters with very small dimensions, low cost, and good reliability. Both digital repeaters that are without timing and regenerators that include timing have been developed. Their circuitry and the corresponding signal shapes are described. The dc power-feeding system and the fault-location system are also discussed. An experimental field trial with the Deutsche Bundespost was performed over 10-repeater sections of the International Telephone and Telegraph Consultative Committee (CCITT) normal coaxial tube with a section length of 1/2 mi, The experiments confirmed that a long-haul digital transmission system of 560 Mbits/s, and later of 1100 Mbits/s using the described system concept and technology, can be established with relatively low cost and good reliability.     

Demonstration of 2.488 Gbit/s transmission on the UK—Channel Islands No 7 submarine cable system

The recently-installed UK—Channel Islands No 7 cable system is a 132 km unrepeatered, twelve optical fibre, 140 Mbit/s system. In February the cable was used for a series of tests to demonstrate new transmission and receiver equipment developed at British Telecom Research Laboratories (BTRL). The paper describes first the use of erbium fibre power amplifiers to achieve two-way transmission over the system at 2.488 Gbit/s, and then the testing of a novel semi-ruggedised laser PIN receiver.     

A single chip regenerator for transmission systems operating in the range 2-320 Mbits/s

Circuit and operational details of a single chip regenerator, developed by BTRL, are presented. The device is capable of operation over the entire span of currently agreed CCITT hierarchical transmission levels from 2 Mbit/s to 140 Mbits/s. Extension to 280 Mbits/s (320 MBd when coded by 7B8B for optical system applications) is also demonstrated to be possible.     

2488Mbit／s SDH系统与设备

由我国自行研制和开发的２４８８Ｍｂｉｔ／ｓ ＳＤＨ复接传输设备和再生中断设备已经成功地应用于从海口市至三亚市长途大容量光缆传输系统。其中还配有若干个１５５Ｍｂｉｔ／ｓ复用设备。本文将简要地介绍该系统的构成及设备特征等情况。     

British Telecom 565 Mbit/s lightline system

British Telecom is currently developing a 565 Mbit/s trunk optical fibre system which incorporates both multiplexing and line transmission. The system will operate at 1.3 μm over single-mode fibre with a 30 km repeater spacing. Extensive use is being made of ECL uncommitted logic arrays (ULAs) manufactured at British Telecom Research Laboratories (BTRL) and derived from the reliable ECL 40 process as used in submarine cable system integrated circuits. Details of the system design are presented together with the initial results of a laboratory system built out of commercially available components to establish confidence in the design.     

Transmission experiments at 560 Mbit/s and 140 Mbit/s using single-mode fibre and 1300 nm LEDs

Transmission at 560 Mbit/s has been demonstrated using single-mode fibre and LEDs at 1300 nm. Surface-emitting, edge-emitting and super-radiant LEDs were used to transmit over maximum distances of 4.5 km, 15 km and 25 km, respectively. At 140 Mbit/s, the corresponding distances achieved with the same set of LEDs are 7.5, 35 and 50 km. respectively.     

COS 2 Experiment in Turin: Field Test on an Optical Cable in Ducts

"COS 2" is the second Italian field trial with an optical cable. In this experiment about 5 km of optical cable were installed in normal telephone ducts of the Turin local network between two telephone exchanges. The cable has a capacity of 8 fibers, but, for cost reasons, in 4 of the 5 km of cable only 3 fibers were inserted. An installation procedure was developed, allowing the independent laying of several cables in one duct; it was possible to pull up to 1 km of optical cable in order to minimize the number of splices. A special splice (Springroove^®splice) and splicing technique, not requiring the use of a microscope or other intricate tools, were employed. Field measurements of transmission characteristics (attenuation and bandwidth) were performed by means of specially designed measurement equipment. An experimental 140 Mbit/s system was tested on a link about 9 km long (without intermediate repeaters) obtained using this cable.     

1.5 ?m optical heterodyne system operating over 30 km of monomode fibre

A 1.52 ?m wavelength 8 Mbit/s system using heterodyne detection is demonstrated over 30 km of installed monomode fibre cable. Sensitivity improvements of 14 dB over direct detection were obtained at the remote receiver with only ?27 dBm local oscillator power. It was not necessary to use special polarisation-maintaining fibre to obtain these results.     

Adaptive quantised feedback equalisation for FSK heterodynetransmission at 150 Mbit/s and 1 Gbit/s

An adaptive quantised feedback equaliser has been used in an FSK heterodyne receiver to overcome the nonuniform frequency modulation response of a DFB laser transmitter in FSK transmission experiments at 150 Mbit/s and 1 Gbit/s with fibre spans of 121 km and 136 km, respectively     

Coherent lightwave transmission over 150 km fibre lengths at 400 Mbit/s and 1 Gbit/s data rates using phase modulation

We report coherent lightwave systems experiments over 150 km employing phase modulation at speeds of 400 Mbit/s and 1 Gbit/s. Bit error rates lower than 10?9 were attained with no evidence of an error rate floor. Receiver sensitivities of ?53.3 dBm and ?44.5 dBm (10?9 BER) achieved at 400 Mbit/s and 1 Gbit/s with a new balanced mixer receiver correspond to improvements of 10.7 dB and 7.5 dB over the best previously published direct detection results.     

1064 nm, 565 Mbits/s PSK transmission experiment with homodyne receiver using synchronisation bits

An optical 565 Mbit/s transmission system at 1064 with phase shift keying and homodyne detection using a new carrier recovery technique is presented. The phase error signal in the receiver is obtained by means of synchronisation bits. This method combines the advantages of the Costas loop with the simplicity of the pilot carrier technique.<>     

155Mbits/s大气传输光通信系统及其测试

研制了通信速率达 155Mbits/ s的大气传输光通信系统 ,传输距离为 2 km,采用光纤输入、光纤输出方式。介绍了该系统的设计考虑、基本原理、系统组成等 ,总结了长期外场实验的结果 ,该系统具有一定的实用价值与市场潜力。     

Injection-locked 1.5 ?m InGaAsP/InP lasers capable of 450 Mbit/s transmission over 106 km

The fluctuation of longitudinal modes of a high-bit-rate modulated 1.5 ?m InGaAsP/InP laser is greatly improved by injection-locking technology. A 106 km transmission at 300 Mbit/s and 450 Mbit/s was achieved with tolerable transmission losses of 37.2 dB and 36.2 dB, respectively, which implies a potential transmission distance of over 145 km.     

500 Mbit/s transmission experiment using 1.3 ?m wavelength InGaAsP/InP high-speed surface-emitting DH LEDs

A 1.3 ?m-wavelength high-speed surface-emitting DH LED, with 0.6 ns rise time and 1.3 ns fall time, has been developed by optimal design of both the LED parameters and driving circuit. A 500 Mbit/s RZ pseudorandom pulse transmission experiment using the high-speed DH LED has been performed with a 5.7 dB level margin over a 2.7 km optical fibre. The 500 Mbit/s LED system feasibility has been confirmed.     

Design and Performance of WDM Transmission Systems at 6.3 Mbits/s

One- and two-way 6.3 Mbit/s optical transmission systems employing wavelength-division-multiplexing (WDM) are designed for application to telephone networks. Multiplexing at two wavelengths, 1200 and 1300 nm, as well as that at 810 and 890 nm, is found to be effective after taking the application fields and present fabrication techniques for optical multiplexers into account. Requirements for optical multiplexers are clarified through SNR design in which crosstalk is dealt with effectively. Optical multiplexers composed of newly developed dielectric multilayer thin-film filters are designed to meet the systems' requirements, and good transmission quality is confirmed for the systems by experiments.