Hitachi, Ltd.

Hitachi Industrial Equipment Systems Co., Ltd.

Takamasa Kawaguchi

Tomoichi Ebata

Takayoshi Fujioka

Hitoshi Ogasawara

Yutaka Shimogaki

Nobuyoshi Ando

Shinya Yoshihara

The present invention provides a transmitter comprising: a plurality of antennas; and a radio transmitting part transmitting from each of the antennas a positional information signal containing the same positional information, the positional information being transmitted from the antennas through channels which are different between the antennas. The transmitter enables prevention of the positioning error and the positioning time from increasing by solving problems of null points and signal interferences, problems relating to a positional information transmitter disposed indoors, in a positioning system for acquiring a current position both indoors and outdoors.

Positional information transmitter, communication terminal, and positioning system using position data

The present invention provides a positional information transmitter, a positional information receiver and a position measuring system capable of measuring a position under moving circumstances. The positional information transmitter transmits positional information for specifying the current position. The positional information transmitter comprises a memory unit which stores therein a plurality of first positional information indicative of the latitude of the current position and a plurality of second positional information indicative of the longitude of the current position, a transmission unit which generates a first positional information signal corresponding to a wireless signal including the first positional information stored in the memory unit and a second positional information signal corresponding to a wireless signal including the second positional information stored therein, and transmits the generated first and second positional information signals, and a timing controller which controls the transmission unit in such a manner that the transmission unit repeatedly transmits the first positional information signal in different periods and repeatedly transmits the second positional information signal in different periods.

Positional information transmitter, positional information receiver, and position measuring system

A GPS signal transmitter configured with a reduced number of components and achieving low cost, space saving, and low power is provided. A GPS signal transmitter of the present invention includes: a crystal oscillator; a carrier wave generator that outputs a first carrier wave and a second carrier wave whose phase is inverted to the phase of the first carrier wave, using a clock output by the crystal oscillator; a microcomputer that is driven with the clock output by the crystal oscillator and outputs a control signal based on a C/A code which is a pseudo random code; a switch that switches over between the first carrier wave and the second carrier wave according to the control signal from the microcomputer and generates a modulation wave; and an antenna that transmits the modulation wave by radio.

GPS signal transmitter and signal transmission method thereof

A position information transmitter including: a digital processing device including a CPU and a position information database storing position information of the position information transmitter and information of channels used by other position information transmitters; and a radio transmitting device executing a signal modulation, wherein the digital processing device generates spread spectrum signals from the position information of the position information transmitter and information of channels used by other position information transmitters, by using the C/A code, and the radio transmitting device modulates the spread spectrum signals and transmits modulated signals as a radio signals.

Positioning system, position information transmitter, communication terminal, and control method of the positioning system

In a positioning system comprising a position information transmitter that transmits a position information signal containing position information indicative of a position as a signal compatible with a satellite positioning signal transmitted from an artificial satellite and a communication terminal that when receiving the satellite positioning signal, finds a current position of the communication terminal by finding a position of the artificial satellite and that when receiving the position information signal, finds a current position of the communication terminal based on the position information, the position information transmitter transmits the position information signal containing a boundary flag that determines which of the satellite positioning signal or the position information signal each of correlators of the communication terminal is to receive, and the communication terminal sets which of the satellite positioning signal or the position information signal each of the correlators is to receive based on the boundary flag.

A wireless device according to the present invention minimizes the need for changing a communication route in an ad hoc network including wireless devices used for base stations, fixed stations, and mobile stations that are turned on/off or moved, wherein, when wireless devices cannot directly send or receive radio waves, data can be transmitted between them by relaying data via other wireless devices that can directly send or receive radio waves (multi-hopping). In selecting a communication route, a communication route that includes wireless devices that are turned off or moved least frequently is selected.

Growing community of inventors

Yokohama, Japan

Takamasa Kawaguchi