| 摘要 |
Identification tags are used to distinguish a unique tagged item from among a plurality of items. Tagged items are searched by scanning the items with an interrogation signal. The tag emits an observable signal when it receives an identification that matches the identification contained in the tag. When an interrogation signal is not present, the tags sleep at a very low power level or are passively unpowered. A quasi-passive wake-up function employs a continuous low power standby mode, comparing a received signal to a predetermined signal and waking up the device when the predetermined signal is received. The tags can talk back to the interrogator, permitting them to respond with an identification code or to be remotely programmable. The tags can be powered by alternative power sources, including by solar cells or photocells capturing ambient light or a signal received from the interrogator.
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