Method and device for remote monitoring of objects placed in a room

摘要

The receiver (12) is a label with a micro-circuit behind it, and mounted in a holder (14). A loop antenna (16) receives interrogation coded signals (17) from a remote transmitter via another loop aerial (32). The receiver has a coded response (28) which is derived from a look-up table (24) and matches the interrogation signal sent. The coded signal is transmitted from the label loop antenna on a second carrier frequency (F2) and received by a loop antenna and received by a loop antenna in the transmitter area, and analysed to determine if it is the correct response.