| 摘要 |
A system for tracking objects outdoors. Tags (202) attached to objects such as trailers include GPS receivers (203). Tags transmit uncorrected position and satellite data to a base station (205), where differential corrections are applied, providing 2-5 meter accuracy of the position of the tag and object. Tags are on a low duty cycle. When a tag powers on, it receives accurate tim e and current satellite data from the base station, enabling the tags to acqui re the satellite signal quickly and with minimum power consumption. When a tag is out of base station range, the tag periodically calculates and archives its position. The tag may also include Real Time Locating Systems technology, to enable tracking to continue when the tag moves indoors and becomes inacessib le to GPS satellite signals.
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