Airport dating protocol
considerable research and development work has to be done before the remaining basic problems in reflected-power communication are solved, and before the field of useful applications is explored." Mario Cardullo's device, patented on January 23, 1973, was the first true ancestor The initial device was passive, powered by the interrogating signal, and was demonstrated in 1971 to the New York Port Authority and other potential users.
RFID tags can be either passive, active or battery-assisted passive.
An active tag has an on-board battery and periodically transmits its ID signal.
A battery-assisted passive (BAP) has a small battery on board and is activated when in the presence of an RFID reader.
An early demonstration of reflected power (modulated backscatter) RFID tags, both passive and semi-passive, was performed by Steven Depp, Alfred Koelle, and Robert Frayman at the Los Alamos National Laboratory in 1973.
A radio-frequency identification system uses tags, or labels attached to the objects to be identified.