Kokusai Denshin Denwa Kabushiki Kaisha

Yotaro Yatsuzuka

Shu Yamamoto

Takaya Yamamoto

Katsuyuki Yamazaki

Katsuyuki Yamamoto

Chuichi Ota

An optical access system is disclosed in which subscribers' terminals and optical coupler-splitters of nodes are maintenance-free and required control is effected on the part of the central office alone. At a first position, down-link optical digital signals are generated, which are made '1s' every n bits (n being an integer equal to greater than 2). The optical digital signals, except a train of optical pulses every n bits, are sent as down-link information over a transmission line. At a second position, the optical digital signals, except the optical pulse train, are demodulated from the transmitted down-link optical digital signals, and in an optical gate circuit on which the down-link optical digital signals are incident, up-link optical digital signals based on up-link message data is formed in synchronization with the optical pulses corresponding to every n-th bits and is transmitted to the first position over the transmission line. At the first position, the up-link optical digital signals sent from the second position is received from the transmission line.

Optical access system

A bilateral optical transmission system for pulse information disclosed which can accommodate variations in the relationship between the down-link signal transmission rate and the up-link one. A single bilateral optical transmission line is laid between first and second positions. A transmission pulse train with pulse transmission time slots set therein at fixed time intervals is provided onto the transmission line from the first position. A return pulse train is retransmitted from the second position to the first position over the bilateral optical transmission line. The return pulse train is obtained by gating the transmission pulse train with up-link information pulses from the second position to the first position in synchronization with up-link pulse transmission time slots for the transmission of the up-link information pulses so that at least one predetermined transmission time slot in each unit transmission period defined by a predetermined number of pulse periods in the transmission pulse train is used as the up-link pulse transmission time slot. At the first position, at least one time slot other than the up-link pulse transmission time slot in each unit transmission period is used as at least one down-link pulse transmission time slot for the transmission of down-link information pulses from the first position to the second position.

Bilateral optical transmission system and optical transceiver for pulse

A wide-band hybrid network, in which a signal received from a four-wire section is applied to a first balanced amplifier and a second balanced amplifier. The output of the first balanced amplifier is applied to one opposed terminals of a main bridge circuit which has an arm including terminals connected to a wide-band two-wire transmission line. The output of the second balanced amplifier is applied to one opposed terminals of an auxiliary bridge circuit which has an arm substantially equivalent to the impedance of the wide-band two-wire transmission line. A differential amplifier is employed for receiving signals of respective other opposed terminals of the main bridge circuit and the auxiliary bridge circuit. The output of the differential amplifier is applied to another four-wire section.

Growing community of inventors

Yokohama, Japan

Yotaro Yatsuzuka