| 摘要 |
PURPOSE: A DOWNLINK GPS system of a positioning terminal and a method thereof are provided to reduce a base station constructing cost by separating the base station into a main base station having accurate time synchronization member and auxiliary base stations. CONSTITUTION: A downlink GPS system includes a base station having a main base station(22) and auxiliary base stations(24a,24b,24c) and a terminal(10). The main base station includes a time synchronization member, an information storage, a modulator, and an RF transmitter. The time synchronization member includes an internal reference clock generator and synchronizes times in base stations with the reference clock. The information storage stores information to be transmitted as positioning signals. The modulator modulates the positioning signals to transmitting signals in synchronization with the reference clock. The RF transmitter wireless transmits the transmitting signals via an antenna. The terminal receives the wirelessly transmitted signals, calculates arrival timings of the received signals to determine its position. |
