Optical fiber telecommunication networks are growing larger and larger today. Optical fiber cables with high-fiber-count are needed, and related technologies on all over the telecommunication field, such as maintenance, connection, etc. In this paper, some recent reports mainly from NTT (Nippon Telegragh and Telephone Corp) are reviewed, and the trend on optical fiber and optical cable is described.

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In order to broadcast HDTV programs via broadcasting satellite. MUSE digital transmission system has been developed and utilized for the first time. It transmits HDTV signals from studios in Tokyo to Shobu-Kuki earth station. The 129.6Mb/s bit rate is realized in H4 channels in broadband ISDN, which will be used generally In the near future. This system is using STM-1 of the B-ISDN. and also network terminal CODEC for this system has been developed.

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When using wireless diffused optical channel to form computer network system within a room, a real office room or shop-floor environment represents complex reflective properties. In order to establish guide lines for the design of wireless in-house optical communication sistem via diffused channel, we must describe effects of multipath dispersion upon data transmission performance. In this paper, we theoretically derive a impulse response of diffused optical channel and numerically analyze the time-spread and average power of the impulse response. It is showed that they will limit the attained maximum bit rate without Intersymbol interference in subcarrier DPSK/IM optical communication system(BER = 10^<-9>).

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Japanese broadcasting satellites, currently, are operating with smaller EIRP than that planned at the WARC-BS. Moreover home dishes are also smaller than those planned. Koreasat program which has been recently developed implies possible interferences to the Japanese system. Required cross-polar characteristics for the Japanese home dishes are studied. A 23dB cross-polar discrimination would be required at northern Kyushu area, if the WARC-BS-planned EIRP and orbital position are adopted to the Koreasat. Farther study should be required when the precise system parameters of the Koreasat are revealed.

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As a wide aspect EDTV system, NIV has developed and experimented EDTV hardware systems of "L-mode" (Letter box mode) and "W-mode" (Window mode) which is an intermediate sheme between the letter box method and the side panel method. This paper reports on the satellite transmission experiment using these hardware systems to transmit encoded signals through international satellite transmission lines from Tokyo and Montreal to Las Vegas in the NAB'91 exhibition held in April 1991.

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ISDB is a new infrastructure for broadcasting taking advantage of advanced electronic technologies. It can not only integrate and transmit a large variety of 'services but also This paper describes the concept of ISDB provide services using a number of different media. and discusses the signal transmission system using one satellite broadcasting channel of the 12GHz band. In one satellite channel, it may become feasible to transmit more than two television programs and many data services by means of lately developed efficient coding methods.

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