| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and system where a position of a user terminal is quickly discriminated with high accuracy. SOLUTION: A communication satellite 10 sends a message with a user terminal 44 and an earth station 38 and evaluates a position of the user terminal 44 through Doppler shift and a propagation delay. In the case that two communication satellites 10 or over are recognized by the user terminal 44, a combination of propagation delays is used for pluralities of the communication satellites 10. In addition, the user terminal 44 measures an arrival time of a signal from a navigation satellite 142 and sends an identifier of the navigation satellite 142 and the arrival time of the signal to the earth station 38, where the delay signal from the navigation satellite 142 is processed. The earth station 38 calculates the position of the user terminal 44 and informs it to the user terminal 44. |
