| 摘要 |
<p>A dual mode electronic identification system using a tag which has an RF receiver and transmitter contained therein. In the first mode the tag responds to an interrogation signal by transmitting an identification data to the interrogator. In the second mode the tag periodically transmits an identification beacon signal to a directional sensing antenna which uses the signal to compute the position of the tag. The power supply for the tag operates from an internal battery or from power received from a portal signal via a tag receiving antenna. The battery can be automatically turned off when the tag is in the portal area and the unit can be shifted into the battery operated beacon mode when the tag is removed from the portal area.</p> |
