Fiber-optic access system integration is the key to providing various kinds of services to home users. The combination of ATM- and SCM-PON systems is essential to support a high-speed data service and analog/digital video distribution services. From this viewpoint, a frequency-division- multiplexing technique for digital baseband and subcarrier multiplexed signals is required to achieve system integration. However, system integration for these two access systems has not been fully investigated yet. The SCM-PON system, which uses a super wideband optical FM converter, will enable these two different kinds of access system (ATM and SCM) to be integrated. In this paper, we describe experimentally obtained results for frequency- division-multiplexed signals consisting of digital baseband and subcarrier- multiplexed signals. The experiments were carried out using a 622-Mb/s baseband signal and an FM-converted signal containing AM and 64QAM signals. The experimental results reveal that the inter-channel interference between the digital baseband and FM-converted signals restricts the number of subcarriers for AM and 64QAM. With an intermediate frequency of 3 GHz for the FM-converted signal, an FDM signal consisting of 622-Mb/s baseband, 30 carriers of 64QAM, and 11 carriers of AM was successfully transmitted.

The information communication service vision for the 21st century -"Visual", "Intelligent" and "Personal" or VI&P- was proposed by NTT, and efforts to develop the techniques necessary to realize this service vision on time are now being accelarated. Among VI&P, visual communication services are expected to play major roles in this future vision. Particularly, visual telephone and related services will become very attractive services. This paper gives an evolutional perspective of visual communication services and the technologies to support them and presents the clear prospect of our 21st century service vision.

This paper discusses research trends in high-speed LANs, which are leading the way to private networks. It also mentions issues that need to be solved to achieve high-performance seamless networks.

This paper describes designing on required signal to crosstalk power ratio of symmetrical cable for bipolar pulse transmission. Error rate in bipolar pulse transmission is discussed taking into account average signal to far-end crosstalk power ratio, average signal to near-end crosstalk power ratio and their standard deviation. Experiments were conducted with regard to the relation among average signal to crosstalk power ratio, its standard deviation and error rate. Calculated and measured results show good agreements. From these results, designing on required signal to crosstalk power ratio and its standard deviation in dB for required error rate is clarified.

This paper proposes a new approach to the problem of efficient digital coding of the NTSC composite color TV signal. First, a new method, named Comb-Filter Integration method", of deriving a prediction function effective for the NTSC composite signal is introduced. This method is based on the technique of integrating a simple comb-filtering operation into an arbitrary linear prediction function tailored for monochrome TV signals, and thus coverting it to a prediction function effective for the NTSC signal. Practical examples of such composite prediction functions are shown. Then, 32 Mb/s and 44 Mb/s DPCM systems, using one of these prediction functions, are described along with their simulated performances. The results show that these systems are promising for the high-quality transmission of the NTSC signal.