System for providing location-specific data to a user

摘要

An FDMA/TDM satellite-based digital broadcast system is used to provide digital maps and other types of data to users at remote locations. User selection of the desired data is achieved by monitoring the TDM downlink channels of the broadcast system in accordance with a predetermined schedule or until a specific identification code is detected. The user terminals are equipped with Global Positioning System (GPS) receivers which allow the positions of the users to be determined. Based on the user positions, the user terminals are able to convert general data to location-specific data tailored to the needs of the user. The general data may comprise a digital map covering a wide geographic area, and the location-specific data may comprise a map covering a portion of the geographic region where the user is located.