Nec Corporation

Ihi Aerospace Co., Ltd.

Shoji Endo

Motoya Iwasaki

Susumu Otani

Seiji Kachi

Ichiro Yamaguchi

Shinichi Kono

Shuji Hagiwara

Hiroyuki Kawadu

Tokuichiro Ojima

A pulse rocket motor has a hollow cylinder-like first grain situated in a rear section of a pressure vessel; a first igniter for igniting the first grain; a hollow cylinder-like second grain situated in a front section of the pressure vessel; a second igniter for igniting the second grain; and a dividing sheet member that covers the second grain within the pressure vessel. The dividing sheet member includes a dividing sheet expanding at least along the inner circumferential surface of the second grain and holders formed integrally with the dividing sheet at both ends of the dividing sheet by cure adhesion and attached to the pressure vessel. The dividing sheet includes a brittle portion that expands along the inner circumferential surface of the second grain through a rear end face of the second grain and is more brittle than other portions.

Pulse rocket motor including a dividing sheet for separating the first grain propellant from the second grain propellant

A transmitting and receiving apparatus for satellite communications, whose sizes of signal processing and apparatus are not made to be large, and which can make the transmission delay minimum caused by retransmission and is easy to be carried and installed, is provided. The transmitting and receiving apparatus for satellite communications provides a transmitting data collision detector, a first random access controller and a second random access controller. When the transmitting data collision detector detects collision of a transmitting packet data signal &ldquo;Sb&rdquo; transmitted through the first random access controller and a transmitting packet data signal &ldquo;Sd&rdquo; transmitted through the second random access controller, the transmitting data collision detector outputs a collision detecting signal to the second random access controller. The second random access controller retransmits the transmitting packet data signal &ldquo;Sd&rdquo; by making the transmitting timing of the transmitting packet data signal &ldquo;Sd&rdquo; delay without waiting for reception of an arrival confirmation signal for the transmitted data from a hub station.

Transmitting and receiving apparatus for satellite communications

A satellite packet communication system comprising a central station and VSAT stations. The central station generates chip-rate clock pulses and transmits a series of data on timeslots of a frame to a satellite transponder, and a plurality of terminal stations. Each VSAT station receives the frame from the transponder and recovers the chip-rate clock pulses from the received frame. A pseudorandom number (PN) sequence generator, provided in the terminal station is synchronized with the recovered chip-rate clock pulses for generating bits of a PN sequence with which packetized data bits are pseudorandomly modulated and transmitted in burst form to the transponder. The central station includes a correlator which is synchronized with the central station's chip-rate clock pulses to detect correlations between the pseudorandomly modulated data bits a sequence of pseudorandom numbers corresponding to the PN sequence bits of the terminal stations.

Spread packet communication system

Growing community of inventors

Tokyo, Japan

Shoji Endo