| 摘要 |
A location system in a cellular communication network has a first set of base stations which transmits and receives signals in a first communication format. The second set of base stations transmits and receives signals in a second communication format. All the base stations transmit known signals at predetermined times for use in deriving location data. A transmitting and receiving unit of the known location determines the times of arrivals of these signals from each base station in each set of base stations. Similarly, a mobile unit at an unknown location determines the times of arrival of the signals from each base station. By comparing timing differences between signals received at the unknown location and signals received at the known location, it is possible to determine the unknown location therefrom. This can then be transmitted back to either of the sets of base stations. In a situation where two communication networks are used, the mobile units will be dual mode transmitting and receiving units.
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