800 Mbit/s Digital Transmission System Over Coaxial Cable

800 Mbit/s digital transmission systems, using nonredundant three-level and four-level codes, have been studied as a means of providing an economically attractive digital transmission system. These systems have been designed to be compatible with a 60 MHz analog system in repeater spacing and repeater size, so as to be easily introduced into the existing network. These systems with 11 520 telephone channels, exceed the 60 MHz analog system in both capacity and economy. Due to repeater construction factors, it became clear that the three-level code is more suitable. This paper describes the design and performance of 800 Mbit/s digital transmission systems and repeaters.     

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.     

An 800 Mbit/s optical transmission experiment using a single-mode fiber

It has been confirmed by a preliminary transmission experiment that a repeater spacing at 800 Mbits/s can be lengthened up to 7.3 km, by using a combination of a low-loss single-mode fiber and a well designed AlGaAs laser. The laser is modulated by a signal current superimposed on a dc bias current above the threshold. This modulation scheme avoids the spectrum broadening of the laser at the cost of extinction ratio degradation. A discrepancy of about 13 dB exists between the measured and the calculated error-rate performance curves. The major part of the discrepancy, 10 dB, is due to the extinction ratio degradation.     

565Mbit／s光中继器插分方式

本文叙述了565Mbit/s光中继器插分方式,并进行了计算机电路模拟和实验。     

An Experimental 50 Mb/s Fiber Optic PCM Repeater

An experimental repeater for amplification and regeneration of 50 Mb/s fiber-optical pulses has been built and tested. For the receiver either Si p-i-n or avalanche photodiodes are used in conjunction with a high impedance FET input amplifier. The high voltage for the avalanche photodiode is generated internally and controlled by the received signal. This AGC circuit is capable of compensating for temperature changes of the avalanche gain over the range of-40 - +60degC. The optical transmitter consists of either a GaAs light emitting diode or a GaA1As laser diode coupled to optical fibers and directly modulated by a current driver with 30 percent electrical efficiency. For 10^-9error rate, the required average optical signal power for a pseudorandom signal is p-i-n diode: -41.5 dBm; avalanche diode: -56.6 dBm. The optical output power into a fiber with 1 percent index difference is LED: -17 dBm; GaAlAs laser: 0 dBm. The repeater power requirement is about 2 W.     

800 Mbit/s optical transmission experiments with dispersion-free fibres at 1.5 ?m

By using dispersion-free single-mode fibres at 1.5 ?m, where silica fibres have minimum loss, an optical transmission experiment was successfully carried out at 800 Mbit/s with 20 km repeater spacing. Error rate against receiving optical level characteristics showed that the optical power penalty caused by fibre dispersion is negligible after long line transmission at 1.5 ?m.     

140 Mbit/s全光波长转换的实验研究

对基于半导体光放大器交叉增益调制的波长转换进行了实验研究。实现了速率为１４０Ｍｂｉｔ／ｓ 信号的１．３１５２ μｍ 和１．３０１４ μｍ 间的波长转换。并对实验结果作了解释     

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。     

A High-Reliability 565 Mbit/s Trunk Transmission System

A high-reliability 565 Mbit/s trunk transmission system capable of operating over a 25.5 dB fiber section loss at 1.3 μm is described. Details of the line terminal and repeater design are presented, together with an outline of the integrated circuit design and process. Aspects of the line code and interface choice are also discussed in relation to the optical receiver, transmitter, and supervisory circuits. Finally, systems design aspects are considered and field experience resulting from a system installation spanning 77 km between Birmingham and Derby is reported.     

400 Mbit/s Digital Repeater Circuitry Provided by a New Design Method and Beam Lead GHz Transistors

A stable, compact, and high-performance regenerative repeater circuitry, suitable for digital transmission systems up to several hundred Mbit/s, has been provided through utilization of new devices, such as 7 GHz beam lead shielded junction transistors, and through a new computer-aided design method, and has been successfully applied to the 400 Mbit/s experimental coaxial cable PCM system. Major features of this repeater circuitry are: (1) an equalizing amplifier with low noise figure (7.6 dB), small intersymbol interference (12%), and automatic line equalization of 21 dB tracking range at 200 MHz; (2) a regenerative output circuit with bipolar pulses of 2.4 Vop amplitude and 700 ps rise time; and (3) total performance with sufficient noise margin (10 dB for error rate 10^-11over a line of 56 dB loss at 200 MHz), small static pattern jitter (20°pp), smaller size (270 times 160 times 52mm), and lower power (5.8 W). These have been achieved by use of: (1) new devices such as beam lead transistors with fTof 7 GHz,Leof 0.2 nH andCobof 0.4 pF and tantalum thin film hybrid integrated circuits; and (2) a new CAD system including block simulation, network design/ simulation, layout design subsystems which use transmission quality (error rate and jitter) as a design criterion, and which can also be directly connected to the manufacture automation systems, e.g., for mask preparation, and transistor mounting by bonding.     

An Interframe Coding System for Video Teleconferencing Signal Transmission at a 1.5 Mbit/s Rate

This paper describes the interframe coding system (TRIDEC 1.5) used for NTSC color television signal transmission at a 1.5 Mbit/s rate. TRIDEC 1.5 is developed with the intention of making video teleconferencing service more economical. The system utilizes the following highly efficient coding techniques: 1) interframe combinational difference coding 2) temporal subsample coding 3) noise reduction 4) demand refreshing to protect against channel errors, which makes periodic forced refreshing unnecessary. In addition, new coding parameter control methods have been devised to prevent buffer memory overflow. The subjective evaluation test results make it clear that the encoded picture quality is good enough for teleconferencing use.     

Repeater spacing of 280 Mbit/s single-mode fiber-optic transmission system using 1.55 µm laser diode source

This paper describes an attainable repeater spacing for a high bit-rate single-mode fiber-optic transmission in the 1.55 μm wavelength region where laser mode partition noise comes to be significant. An expression for evaluating mode partition noise is given as the form involving the influence of laser spectral fluctuations under high bit-rate modulation, together with the intersymbol interference and the equalized pulse shape in tile optical receiver. After the validity of its numerical results is confirmed experimentally, the resulting evaluation of laser mode partition noise is connected to a systematic discussion on the attainable repeater spacing of a 280 Mbit/s fiber-optic transmission system operating at 1.55 μm, along with fiber loss versus dispersion tradeoffs. This discussion permits the attainable repeater spacing to be 60-70 km for the combination of a laser diode with 1.5-2.0 nm spectrum broadening and a fiber with the loss of 0.5 dB/km and the dispersion of 4-6 ps/km - nm.     

Performance of a 400 Mbit/s System over a Line-of-Sight Path

During November 1971, a 400 Mbit/s quadriphase-shift-keyed system was operated at 13.3 and 14.9 GHz over a 22.8-km line-of-sight path. This path was chosen because of its high incidence of meteorological conditions favorable to anomalous propagation. Performance of the system during fading periods is reported here. Additional information from extensive meteorological measurements near midpath is presented to identify the source of the fading. The dual frequency measurements for spaced receiving antennas indicate that diversity reception, properly implemented, would have provided an effective fading remedy.     

基于FPGA的百兆级联以太网系统设计

本文介绍了一种低成本、高效能的工业以太网传输系统，可广泛应用于道路监控、电力监控系统、安防系统、通信系统等。本设计核心芯片采用高性价比的FPGA，主要实现视频数据的采样、复用，解复用、IP打包，解包，以及网管信息的处理。     

400-Mb/s QPSK Repeater for 20-GHz Digital Radio-Relay System

This paper describes the design and performance of a repeater for a 20-GHz high-speed digital radio-relay system with a transmission capacity of 400 Mb/s. The repeater is totally solid state for miniaturization, high reliability and economy with the adoption of microwave IC's, monolithic lC's, and direct oscillation by Gunn diodes in the 20-GHz band. The modulation and demodulation techniques of the repeater employ QPSK, which has a theoretical advantage over FSK, DPSK, or ASK in error rate performance, considering spectrum utilization. The error rate performance is further improved by using a simple digital equalization for intersymbol interference. The error rate performance of this system was measured. From the test results, it became evident that the equivalent carrier-to-noise ratio (C/N) degradation of error rate performance at a 10/sup -6/ error rate was about 5 dB under fixed temperature conditions and that the equivalent C/N degradation due to a -10/spl deg/C to +45/spl deg/C temperature variation was only 1 dB. The experimental 13-hop system employing the repeaters has been operating stably since April 1973.     

140Mb/s宽带交换网络的设计

本文论述了宽带交换机里的关键部件——宽带交换网络的基本原理,着重讨论了在使用中规模高速集成电路设计宽带交换矩阵的过程中应注意的一些问题,并力图给出了基本的解决方法。本设计方案的指导思想之一是全部采用国内组件,这无疑对宽带网的国产化有着极重要的意义。     

Quantized Feedback in an Experimental 280-Mb/s Digital Repeater for Coaxial Transmission

A 280-Mb/s digital coaxial repeater employing two-level transmission with quantized feedback for dc-wander control has been designed and constructed. The linear channel forward path includes a 10-MHz low-frequency cutoff, and the missing low frequencies are supplied by a filtered signal from the repeater output. This approach effectively removes dc wander without use of code restriction, making it possible to use two-level rather than three-level transmission without loss of information transmission. Eye margins are consequently significantly greater than for previously designed 280-Mb/s three-level repeaters. The bandwidth ratio, or ratio of upper to lower 3-dB down points of the signal transmission path, is only 10 for this approach compared to several hundred for the three-level bipolar approach (and more for codes with higher transmission efficiency). This results in greatly reduced susceptibility to interference from lightning and power surges, elimination of preamplifier overload, and simplified repeater design.     

565 Mbit/s optical PSK transmission system with endlesspolarisation control

A 565 Mbit/s optical PSK transmission system incorporating automatic endless polarisation control is reported. A receiver sensitivity of -49.8 dBm was achieved, and the randomly varying polarisation state of the received signal was tracked with no observed degradation in system performance     

Experimental assessment of a 140 Mbit/s coherent optical receiver at 1.52 ?m

Homodyne detection has given a 10 dB improvement in receiver sensitivity over direct detection at a wavelength of 1.52 ?m and a data rate of 140 Mbit/s. This result was achieved with a local oscillator power of only ?32 dBm.     

Transmission of 622 Mbit/s spectrum-sliced WDM channel over 60 kmof nondispersion-shifted fibre at 1550 nm

The transmission of a spectrum-sliced WDM channel at 622 Mbit/s over 60 km of nondispersion-shifted fibre using an optical bandwidth of only 0.23 nm is reported. This is the highest single channel bit rate-length product (40 Gbit/s·km) and smallest channel bandwidth reported to date for spectrum-sliced WDM systems. The bit error rate performance is theoretically predicted and experimentally confirmed and limits on the bit rate-length products of spectrum-sliced WDM channels using nondispersion-shifted fibre in the 1550 nm window are given