Nonlinear phase distortion and its compensation in l.e.d. direct modulation

Differential phase distortion of the light-emitting diode is measured and analysed. An effective technique is proposed to compensate the d.p. distortion. An experimental result shows that 2.8° d.p. distortion has been reduced to within 1°.     

Speckle Noise Reduction in Fiber Optic Analog Video Transmission Using Semiconductor Laser Diodes

This paper investigates the effects of speckle noise on analog video transmission systems using semiconductor laser diodes. The system linearity degradation due to speckle noise is examined using different fiber types. Then this paper proposes a new modulation technique employing a superimposed pulse scheme to reduce speckle noise. It is experimentally confirmed that the proposed modulation method is effective in reducing speckle noise. Based on the above investigations, analog video transmission experiments are performed using single-mode fibers, step-index multimode fibers, and graded-index multimode fibers in the 0.8 and 1.3 μm wavelength regions. The results of the transmission tests have confirmed the feasibility of analog video transmission using semiconductor laser diodes.     

A Review of Broad-Band Fiber System Activity in Japan

In the future information society, various kinds of services will be required in offices, factories, homes, and communities. Fiber optic broad-band systems will play the most important role in the integrated services networks that will provide such services. This paper reviews field trials of fiber optic broad-band systems in Japan, focusing on subscriber loop system technology.     

Trends in standardization on multimedia communications

The authors describe the activities of telecommunication and information standardization organizations, such as the ITU-T, ISO/IEC JTC1, and ISO/IEC related to multimedia communications. Achievements of the related fora and consortia, such as the ATM Forum, IETF, and DAVIC, which play important roles in standardizing multimedia applications, are also described     

Standardization on multimedia communications:computer-telephony-integration-related issues

Computer-telephony integration (CTI) has been developed since the 1960s. It is one of the major emerging multimedia communications applications. It provides enhanced telecommunications services controlled by a computer, that is by integrating the call handling capabilities of PBXs and the data processing capabilities of computers. CTI applications have become more popular and widespread with the rapid and deep penetration of personal computers and the dramatic growth of the Internet since the mid-1990s. CTI applications are being enhanced by means of more integration with Internet capabilities. Several standardization organizations and fora/consortia are developing standards/specifications for CTI in order to cope with the growing demand for multimedia communications. This article describes a brief historical sketch and the state of the art of CTI-related standards and specifications, which are still being developed     

A Field Trial of Fiber Optic Subscriber Loop Systems Utilizing Wavelength-Division Multiplexers

Future subscriber loops will provide various services including broad-band video. Fiber optic technology is the key for introducing these services. The Electrical Communication Laboratories (ECL) of Nippon Telegraph and Telephone Public Corporation (NTT) have been promoting research and development on basic technology of fiber optic subscriber loops, and studying the ways to use fiber optic subscriber loops for new services. As one of the programs, a field trial of fiber optic subscriber loops was planned and conducted in the Yokosuka area from April 1980 until May 1981. This paper first describes fiber optic transmission technologies for subscriber loops. Then, the system configuration and experimental results of the Yokosuka field trial are presented.     

Telecommunications standardization for the new millennium: ITU-T'sstrategies

After reviewing the environmental changes in telecommunications and the market trend toward global convergence, this article examines the evolution of the standards-making process, especially from an ITU's perspective. Projects on IP-based networks and their interworking with the telecommunication networks and MEDIA-COM 2004 are then treated from the viewpoint of the final convergence toward a worldwide global information infrastructure