Hitachi, Ltd.

Masahiko Ikeda

Shigeki Nakamura

Masahiro Ito

Tomiharu Yoshida

Nobuo Hamano

Takashi Yabutani

Masataka Owada

Toshihide Maeda

A transmission or communication system, wherein plural individual elliptical orbits are so defined that an individual right ascension of a north-bound node is established with a designated angle. An artificial satellite is travels on a respective ones of the plural individual elliptical orbit and a group of artificial satellites arranged on respective ones of the plural individual elliptical orbits are used so that at least one of the artificial satellites having a communication system is always viewable within a pre-defined range of operational elevational angle in a zenith direction from a service area. The group of artificial satellites are on respective orbits obtained by combining an inclination angle and an eccentricity squared of the individual elliptical orbit so that a right ascension of north-bound node is a designated angle and a time period during which respective ones of the group of artificial satellites is viewable from ground is substantially identical.

Artificial satellite with an orbit having a long staying time in a zenith direction, an orbit control method and a communication system therewith

A communication terminal for communicating through an artificial satellite, wherein the artificial satellite is placed into an orbit in which an individual satellite orbits on an elliptical orbit so that at least one of the artificial satellites is always viewable within a pre-defined range of operational elevational angle in a zenith direction from a service area. A group of the artificial satellites are satellites on respective orbits obtained by combining an inclination angle and an eccentricity squared of said elliptical orbit so that a time period during which an artificial satellite is viewable from ground is substantially identical and the communication terminal has a transmitter and receiver for transmitting and receiving a signal through the group of artificial satellites.

Communication system, communication receiving device and communication terminal in the system

A broadcasting or transmitting system using an artificial satellite. The artificial satellite is placed into an orbit in which individual artificial satellites orbit on an elliptical orbit so that at least one of the artificial satellites is always viewable within a pre-defined range of operational elevational angles in a zenith direction from a service area. A group of the artificial satellites are satellites on respective different orbits obtained by combining an inclination angle and an eccentricity squared of said elliptical orbit so that a time period during which one artificial satellite of the group of the artificial satellites is viewable from ground is substantially identical to a time period during which another artificial satellite of the group is viewable from the ground.

An information providing method and apparatus for providing information to a moving body via an artificial satellite. Information for selecting a desired information and position information of the moving body is transmitted, from the moving body. Information is provided to the moving body from the artificial satellite depending upon the position information of the moving body and the desired information, on the basis of information from the moving body.

Satellite, satellite control method and satellite communication system

A system and method for a group of artificial satellites. The artificial satellite is placed into an orbit in which an individual satellite orbits on an elliptical orbit so that at least one of the artificial satellites is always viewable within a pre-defined range of operational elevational angle in a zenith direction from a service area. The group of the artificial satellites are satellites on respective different orbits obtained by combining an inclination angle and an eccentricity squared of the elliptical orbit so that a time period during which one artificial satellite of the group of artificial satellites is viewable from ground is substantially identical to a time period during which another artificial satellite of the group of the artificial satellites is viewable from ground.

In order to establish the communication lines among the movable bodies and/or fixed stations and to configure communication system with a small number of satellites, present method has the steps of determining six orbit-related parameters by using a input conditions including a geographical condition of the service area, a desired service time and the tolerance of an ascending vertical angle within which the satellite can be viewed from the service area, and establishing the satellite communication with one or more satellites, an individual satellite being arranged on the orbits selected and combined among plural elliptical orbits corresponding to the determined six orbit-related parameters on which the satellites stay for a sufficiently long time that they may come successfully into sight in the zenith direction.

A communication system, wherein plural elliptical orbits in which an apogee is located on a specified service area are so defined that an individual right ascension of north-bound node may be established with a designated angle. A satellite is made to travel on an individual elliptical orbit and a group of satellites to be arranged on said elliptical orbits are used so that at least one of artificial satellites having a communication system may be always viewable within a pre-defined range of ascending vertical angle in a zenith direction from the service area.

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Hitachi, Japan

Masahiko Ikeda