SCREENING TRANSMISSIONS FOR POWER LEVEL AND OBJECT IDENTIFIER IN ASSET MONITORING AND TRACKING SYSTEMS
A method for communicating to a recipient transceiver from a plurality of transceivers located within the broadcast range of the recipient transceiver includes: transmitting a communication at a first power level such that only a first group of transceivers receive the broadcast, the communication including a command causing each of the first group of transceivers not to respond to a subsequent broadcast; and subsequent thereto, transmitting a communication at a second power level greater than the first power level such that a second group of transceivers greater than and including the first group of transceivers receive the broadcast, but such that only a limited number of transceivers of the second group respond to the broadcast, the limited number of transceivers excluding the first group of transceivers. Each of the plurality of transceivers is associated with a respective sensor for acquiring data and transmitting the data to the recipient transceiver.
1 . A method for monitoring a container having at least one RFID device interior thereto, said method comprising:
providing an RFID device interior to a container, the RFID device periodically transmitting messages;
wherein each of the messages includes information uniquely identifying the RFID device, and
wherein ones of the messages that are transmitted when the container is closed are substantially attenuated by the container, and wherein ones of the messages that are transmitted when an opening in the container is open are not substantially attenuated by the container;
receiving messages transmitted by the RFID device interior the container by a receiving device exterior the container;
whereby ones of the messages that are transmitted when the container is closed are substantially attenuated and/or are not received by the receiving device, and wherein ones of the messages that are transmitted when the container is tampered with and/or when the opening of the container is open are received by the receiving device; and
determining from the messages received from the RFID device whether the opening of the container has or has not been opened and/or the container has been tampered with,
whereby a container having an RFID device therein is monitored for being opened and/or tampered with.
2 . A method for monitoring a container having at least one RFID device interior thereto, said method comprising:
providing an RFID device interior to a container, the RFID device periodically transmitting messages, wherein each of the messages includes information uniquely identifying the RFID device;
receiving messages transmitted by the RFID device interior the container by a receiving device exterior the container; and
determining from the messages received from the RFID device status changes of the container;
whereby a container having an RFID device therein is monitored.
3 . The method of claim 2 , wherein ones of the messages that are transmitted when the container is closed are substantially attenuated by the container, and wherein ones of the messages that are transmitted when an opening in the container is open are not substantially attenuated by the container.
4 . The method of claim 2 , wherein ones of the messages that are transmitted when a status change occurs are received by the receiving device.