| 摘要 |
<p>The invention provides a method of detecting the presence of a moving object (30) in a monitored zone (28) of an electronic identification system in which transponders (32) are activated by a transmitted interrogation signal and then transmit reply signals. The method includes illuminating the monitored zone (28) with said interrogation signal or beam, receiving a reflected and/or reply signal from the monitored zone (28), and separating out a Doppler component, if present, from the received signal. The Doppler component, if present, is investigated. The method further includes determining if a moving object (30) is present in the monitored zone (28) depending on the presence or absence of the Doppler component and, if the Doppler component is present, the characteristics of the Doppler component.</p> |
