| 摘要 |
A vehicle location system incorporating a plurality of ground enhancement stations (10) and at least one satellite (8) to receive encoded transmissions from a radio transmitter aboard a user vehicle (2). The satellite (8) transmits the signals received directly from the user and those relayed by the ground enhancement stations (10) to a base station (14) where a computer (88) calculates the position of the user on the basis of the time difference between the time of arrival of the signals. The use of the ground enhancement stations (10), located throughout the area in which the user is to be located provides lower geometric dilution of precision than purely satellite or purely ground base system, and in combination with the relatively simple transmitter (44) aboard the vehicle (2) and transponders at the ground enhancement stations (10) and satellite (8), substantially reduces the cost of deployment of such a system. |
