Zebra Technologies Corporation
Method, system and apparatus for radio-frequency echo cancellation

Abstract:

An RFID echo cancellation assembly includes: a circulator defining a transmission path from a transmit module to an antenna module, and a reception path from the antenna module to a receive module; a combiner on the reception path between the circulator and the receive module; a variable reflector for applying a cancellation signal to the combiner; a controller for setting an operational parameter at the variable reflector according to an attribute of a transmitted signal from the transmit module; and a coupler defining a segment of the transmission path between the transmit module and the circulator, and a cancellation path between the variable reflector and the combiner. The coupler couples a portion of the transmitted signal to the variable reflector, whereupon the variable reflector generates the cancellation signal based on the operational parameter, for transmission to the combiner via the cancellation signal path.