Nippon Telegraph and Telephone Corporation

Shinichi Aoyagi

Noriki Miki

Kiyomi Kumozaki

Ryuichi Watanabe

Seiichi Yamano

Yasuyuki Okumura

Yoshihiro Takigawa

A point-to-multipoint communication system is presented to enable a reliable, high quality communication using multiplexed optical signals between a central office equipment and a plurality of subscriber's equipment. The system is provided with a plurality of office transceivers in the central office equipment, and the each of the subscribers is provided with at least one subscriber transceiver. The system is designed so that a redundancy system is built-in by providing one of either the office transceivers, a plurality of subscriber's transceivers or the optical connection device, to connect the two sets of transceivers at all times. One of these redundancy systems provides an operating connection between each of the office transmitters which are connected to the office transceivers and each of the subscriber transmitters which are connected to the subscriber transceivers. Therefore, when a malfunction occurs somewhere in the optical network, the least number of the malfunctioning components need to be switched over the the normally functioning system to maintain continued communication services. The present communication system is designed with the least number of active components, therefore, the failure probability is significantly decreased, and repairs if necessary can be preformed quickly. The overall effect of the present system is that interactive point-to-multipoint communication services of high quality and reliability are provided at reasonable cost.

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Tokyo, Japan

Shinichi Aoyagi