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System for transmitting positioning signal

System for transmitting positioning signal description/claims

1. Field of the Invention

The present invention relates to a technique for transmitting a signal for positioning. More specifically, the present invention relates to system for transmitting synchronized signals for positioning.

2. Description of the Background Art

A method of positioning using a signal transmitted from a satellite has been known. By way of example, a GPS (Global Positioning System) signal transmitted from a GPS satellite is used for positioning. More specifically, an apparatus receiving GPS signals transmitted from three or more GPS satellites read data contained in each of the signals, executes a predetermined operation, and calculates positional information. Here, accuracy of time data contained in the data determines the accuracy of positional information, and therefore, a high-precision clock (for example, an atomic clock) is mounted on each GPS satellite. It is noted that the clocks must be synchronized with each other. Therefore, in order to maintain synchronization between each of the clocks mounted on GPS satellites, sometimes it becomes necessary to correct time of a clock on a satellite using time information of a master clock provided on the ground.

A system enabling positioning based on satellite signals, that is, a so-called satellite positioning system may include, in addition to GPS operated by the United States of America as mentioned above, Galileo of which operation is under consideration of the European Union, GLONASS (Global Navigation Satellite System) operated by the Russian Federation and the like.

In the foregoing, conventional art related to the present invention has been described based on general technical information known to the applicant. To the best of applicant's memory, the applicant does not have any information to be disclosed as prior art, before the filing of this application.

When positional information is to be calculated using radio signals as described above, the following problems arise. As it is necessary to mount a high-precision clock on each satellite or a ground-based transmitter as a pseudolite, the cost for building a system for transmitting positioning signals increases.

The present invention was made to solve the above described problems, and its object is to provide a system for transmitting synchronized signals for positioning.

Another object of the present invention is to provide a system for transmitting synchronized signals for positioning using one clock in the system.

In order to attain the above described objects, according to an aspect, the present invention provides a system for transmitting a positioning signal to a receiving apparatus receiving the positioning signal for positioning the receiving apparatus. The system includes one transmitting apparatus transmitting the positioning signal. The one transmitting apparatus includes time keeping means for keeping time, storing means for storing data as an object to be encoded, generating means for generating the positioning signal containing the time, by encoding data stored in the storing means, using a code for identifying a transmission apparatus of the positioning signal, and transmitting means for transmitting the positioning signal generated by the generating means. The system further includes a plurality of relay apparatuses relaying the positioning signal, and supplying means for supplying data specifying positional relation between the transmitting apparatus and each of the plurality of relay apparatuses to the receiving apparatus. Each of the plurality of relay apparatuses includes receiving means for receiving the signal transmitted from the transmitting apparatus, and transmitting means for transmitting the signal received by the receiving means.

Preferably, the supplying means includes output means for outputting the data specifying the positional relation to the generating means.

Preferably, the supplying means includes transmitting means for transmitting the data specifying the positional relation through a path different from a communication path of the transmitting apparatus.

Preferably, the transmitting apparatus and each of the plurality of relay apparatuses are mounted on each of a plurality of artificial satellites.

Preferably, at least one of the plurality of artificial satellites stays space above a predetermined region.

Preferably, each of the artificial satellites navigates maintaining a predetermined positional relation between each of the plurality of artificial satellites.

Preferably, the generating means generates the positioning signal by encoding using a code for identifying an artificial satellite on which the transmitting apparatus is mounted.

Preferably, the time keeping means is an atomic clock.

Preferably, the transmitting means of the transmitting apparatus transmits the positioning signal by wireless. The receiving means of the relay receives the positioning signal by wireless.

Preferably, the generating means of the transmitting apparatus generates the positioning signal by encoding based on spread spectrum system.

Preferably, the signal generated by encoding has a period between one millisecond and one week.

Preferably, the signal generated by encoding has a period between one second and one hour.

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