760 Mbit/s Serial MSK Microwave Modem

Serial modulation and demodulation provide a significant simplification in the hardware realization of high data rate MSK systems. The serial MSK (SMSK) technique results in theoretical performance charateristics identical to conventional MSK. A 750 kbit/s low data rate system and a 760 Mbit/s high data rate system were constructed to evaluate the feasibility of the design concepts. The low data rate system had an overall BER performance degradation of 1.3 dB at a 10^-6BER. The 760 Mbit/s system had a corresponding degradation of 2.0 dB and used direct modulation and demodulation at the 14.7 GHz carrier.     

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.     

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.     

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.     

1.544-Mbits/s Transmission of TV Signals by Interframe Coding System

As a powerful tool for economizing on the digital transmission of videotelephone signals, interframe coding techniques have drawn increasing attention, and various interframe coding schemes have been proposed recently. However, many problems remain to be studied in establishing technical feasibility for these techniques and schemes. This concise paper reports on field trial in which a 1.544-Mbits/s digital transmission of videotelephone signals was conducted over Nippon Telegraph and Telephone Public Corporation's (NTT's) PCM100M digital repeatered line between Tokyo and Yokohama, Japan. The experimental interframe codec is based on the well-understood conditional picture element replenishment algorithm. The object of the field trial was to demonstrate, not the validity of the algorithm itself, but the technical feasibility of the interframe coding system as an entity. Experimental results are satisfactory enough to assure us of the system's practicality in the near future.     

Application of Coded Modulation to 1.544-Mbit/s Data-in-Voice Modems for FDM FM and SSB Analog Radio Systems

The technical issues relevant to providing high-quality digital service over analog radio using 1.544-Mbit/s DS-1 data-invoice modems operating through analog supergroup channels with 256-QAM modulation are reviewed. By means of a typical example, the desirability of increasing the fading margin when operating over FM radio systems is demonstrated. This motivates the consideration of coded modulation as a means of extending the threshold of the modem System, so that operation of the modem can be achieved in supergroup channels located higher in the radio baseband. It is found that trellis coded modulation provides better improvement of threshold performance than lattice coded modulation when the actual coding gain realized near the R0channel bound is used rather than the high signalto-noise-ratio (SNR)asymptotic coding gains. Using Ungerboeck's eight-state trellis code [3], a coding gain of approximately 2 dB is found for operation at 28 dB SNR (1 dB from the R0bound). Furthermore, it is found that even at this low operating SNR (where error events at the coded modulation receiver ouput can be long), high-rate, interleaved Reed-Solomon codes, used for burst noise protection at high SNR, still provide over 2 dB of additional coding gain.     

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.     

Transmission of eight channels×622 Mbit/s and 15channels×155 Mbit/s using spectral encoded optical CDMA

A spectral optical code division multiple access transmission system using forward error correction is demonstrated. Matching channels are recovered error-free with 15 channels operating at 155.52 Mbit/s and up to eight channels operating at 622.08 Mbit/s     

European Collaboration on Picture Coding Research for 2 Mbit/s Transmission

COST 211-a European collaborative research project in redundancy reduction techniques for visual telephone signals-has involved laboratories in Belgium, France, Holland, Italy, Sweden, the United Kingdom, and West Germany since 1977. A broad review is offered of progress made in the empirical optimization of conditional replenishment coding and the parallel development of subjective test and computer simulation techniques with which to assess this and other picture coding methods. An international network of 2 Mbit/s transmission is provided by the European satellite OTS and interest is being generated in further collaboration for a European Videoconference Experiment under the auspices of the CEPT.     

A Highly Integrated Regenerator for 295.6 Mbit/s Undersea Optical Transmission

The requirements of high-speed transoceanic transmission on optical fibers dictate that the line regenerators exhibit an unusual combination of high performance and high reliability. We describe the design and the measured performance of the regenerators developed for a transatlantic system targeted for deployment in 1988.     

建设穗深SDH 622Mbit/s光缆传输系统试验网的设想

本文叙述利用穗深地区现有光缆路由(粤港、榕穗光缆路由)建设穗深同步数字系列(SDH)622Mbit/s传输系统环形网的设想。对PDH、SDH设备进行了比较,对线形传输、环形传输方式进行了比较并用曲线图对环形网两点间最长传输距离的经济性进行了估算。列出了设备的主要技术指标。     

32 Mbit/s Transmission of NTSC Color TV Signals by Composite DPCM Coding

A composite DPCM coding System was developed, which is capable of coding and transmitting an NTSC color TV signal without component separation at a 32.064 Mbit/s rate. The DPCM prediction method used is based on the algorithm that a luminance component prediction valuehat{y}and a carrier chrominance component prediction valuehat{c}are calculated individually, and then the composite signal prediction valuehat{x}is determined byhat{x} = hat{y} + hat{c}. In order to utilize horizontal blanking (HBL) intervals for transmitting active video signals,HBL signals are not transmitted in each line but their representative signals are transmitted once a frame during a vertical blanking interval. A dual word-length coding and quantizing method is adopted, which uses 4 bit and 8 bit words with average word-lengths of 4.4 bits/sample. Codec equipment was fabricated, and coding and transmitting experiments were conducted, using NTT's PCM-100 M digital repeatered line. Experimental results show that this composite DPCM coding system can be employed for digital transmission of NTSC color TV signals, such as color ITV signals, at a 32.064 Mbit/s rate.     

100-channel optical FDM transmission/distribution at 622 Mbit/s over 50 km utilising a waveguide frequency selection switch

100-channel optical FDM transmission/distribution at 622 Mbit/s is demonstrated for a fibre length of 50 km. A polarisation-insensitive waveguide frequency-selection-switch with 10 GHz intervals and an FSK/direct-detection scheme using a Mach-Zehnder filter type optical frequency discriminator are verified as feasible.<>     

Rockwell 135 Mbit/s lightwave system

A new intermediate-capacity digital lightwave system has been developed using digital gate array technology, hermetically sealed optical hybrids, and decision feedback equalization of the lightwave fiber. This paper reviews the technical characteristics and design considerations of the Rockwell LTS-135 lightwave transmission system.     

140 Mbit/s thick-film hybrid regenerator

A prototype integrated hybrid regenerator is described which includes amplifiers and decision and timing recovery circuit components mounted in a single package measuring 20×24.5 mm. Measured performance characteristics are also given.     

A multimode PCM transceiver chip for 1.544-Mbit/s digitaltelecommunications

A 1.25-μm CMOS VLSI device that converts the popular 1.544-Mb/s T1 format used in digital telecommunications to a 4.096-Mb/s system format is described. The transmit and receive functions are implemented with a RAM, a 3088-bit shift register, and 33 K transistors     

实用化565Mbit／s光发送机

本文介绍实用于565Mbit/s速率上的光发送机,并叙述其工作性能及指标。     

140 Mbit/s and 560 Mbit/s FSK heterodyne polarisation diversity receiver using nearly perfect square law demodulators

A new frequency discriminator concept with nearly perfect square law demodulation characteristics is described. The performance of the device is verified in a 140 Mbit/s and 560 Mbit/s FSK heterodyne polarisation diversity transmission experiment.<>     

大规模专用集成电路四次群复接和分接器

本文介绍一组专用集成电路的特性、应用、设计和工艺。     

Packet Reservation Window Multiple Access for Microcellular Voice/Data Transmission

We propose a new packet reservation multiple access (PRMA) scheme for the joint transmission of voice and data traffics in a microcellular medium. The collision resolution protocol within the system is based on a modification of the window random access algorithm, which has superior properties compared to the conventional slotted Aloha. The proposed algorithm, which we call packet reservation window multiple access (PRWMA), works in distinct modes for voice and data without prioritization, and the user performs slightly different operations depending on the information type. Simulation results show that PRWMA outperforms PRMA by a significant margin in terms of voice user capacity.