| 摘要 |
An EOT unit periodically reports its position to an EOT unit tracking station using wireless communication. The location message preferably includes an EOT identifier and a time associated with the position. Optionally, the EOT units are configured to periodically reawaken from a low power state (which may be entered when the EOT units are tipped over while installed on a train or laid on their sides along a wayside or elsewhere) in order to transmit the location message. Optionally, the EOT unit includes a cellular modem and periodically transmits the location message using a cellular network. Optionally, the EOT units are equipped with transceivers and have the ability to receive a query message and transmit a location message in response, and further have the ability to receive a disable message and respond by entering a "no service" state until a special command is entered.
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