| 摘要 |
<p>In a system for the registration of the passage of articles through a previously determined field the transmitter (2) and the receiver (3, 4) are connected to a common aerial (1). A marker (18) on the articles receives and transmits electro-magnetic signals by the passage of a transmitter-and receiver bracket. In order to achieve the greatest possible security from incorrect registration the transmittance-and receiving function changes at a suitably high frequency, and an analytical circuit (7) monitors the number of received signals from the marker (18), and compares the frequency of these to that of the signals which are transmitted by the transmitter (2). The marker (18) consists of an inductive and a capacitive component, and the aerial (1) is shaped like a figure eight. </p> |
