| 摘要 |
A position alert system comprises a position logging unit (1 ) and a data retrieving unit (2). The position logging unit (1 ) comprises a receiver (12) for receiving information defining a position (Pi) of the logging unit (1 ), a storage medium (14) comprising pre-stored information defining a border (B2), and a first processor (13) for: (i) storing a sequence of positions (Pi) at predetermined sequential time instants (ti) defining a route (R) of the position logging unit (1 ), (ii) determining a distance (D1 ) between an actual position (Pi) of the logging unit (1 ) and the border (B2), and (iii) checking whether the distance (D1 ) is smaller than a threshold value (TH1 ), an alerting device (17) coupled to the processor (13) for alerting a user if the distance (D1 ) becomes smaller than the threshold value (TH1 ). The position logging unit (1 ) further comprises a first communication circuit (15). The data retrieving unit (2) comprises a second communication unit (21 ) for establishing a wired or wireless communication with the first communication unit (15), and a second processor for retrieving the sequence of positions (Pi) stored in the storage medium (14) of the position logging unit (1 ) via the second communication circuit (21 ) and for controlling an indicator to indicate whether the route (R) of the position logging unit (1 ) crossed the border (B2) or not. |
