Patent ID: 7839289

Claim:
A system for monitoring a container having an exterior surface with a closable opening therein that when closed defines a closable substantially electromagnetically shielded interior space, said system comprising: an RFID device disposed in the interior space of the container, said RFID device comprising: a memory having stored therein unique identifying information; an antenna for transmitting and/or receiving electromagnetic signals; a modulator coupled to said memory for modulating the unique identifying information stored in said memory; and a transmitter coupled to said modulator and to said antenna for transmitting messages via said antenna, wherein each of the messages includes the modulated unique identifying information; wherein when the closable opening of the container is closed said RFID device therein is substantially electromagnetically shielded and when the container is not closed said RFID device therein is not substantially electromagnetically shielded; and a receiving device exterior to the container, said receiving device comprising a receiver for receiving messages transmitted by said RFID device interior the container; wherein messages transmitted by the RFID device interior the container when the container is closed are received by the receiving device exterior to the container with certain respective power levels and messages transmitted by the RFID device interior the container when the container is not closed are received by the receiving device exterior to the container with different respective power levels; and wherein the power levels of the messages received by said receiving device exterior the container are processed for providing an indication of whether the container is closed, is not closed, has been closed, or has been not closed, or any combination thereof, whereby an opening of and/or tampering with the container may be detected.