| 摘要 |
An electronic tag 10 receives a data message (18, Fig. 2) that has a wake-up section (20) followed by a session section (22). A power manager 28 decodes the wake-up section (20) using a low power decoder 34 that remains energised during a standby state of the tag 10. When an ID detector 40 in power manager detects a predetermined ID code (26, Fig. 3) in the wake-up section (20), a switch 32 is closed to connect a power source, such as a battery 17, to a controller/transceiver 30 which may then decode, process and respond to the information in the session section (22). A particular tag may be uniquely addressed by a combination of the ID code (26) in the wake-up section (20) and identification data in the session section (22). The power manager 28 includes a synchronizer 38 that produces a sync signal in response to a preamble (24, Fig. 3) in the wake-up section (22). The synchronizer 38 goes to a low power state when the sync signal is produced. The sync signal also enables the ID detector 40, which has been in a low power state previously. The interrogation signal carrying the data message (18) encodes the wake-up section (20) at a lower data rate than the session section (22), so that the power manager 28 operates at the lower data rate thus enhancing the low power consumption in the standby state. <IMAGE> |
