Patent ID: 7456747

Claim:
A method for operating an RFID read/write unit with transmitting signal suppression, the method comprising: providing the RFID read/write unit, the RFID read/write unit comprising a radio frequency part including a transmitter and a receiver, and a baseband part based on digital signal processing; producing an amplitude and phase weighted copy of a transmitting signal, namely a compensation signal, with the baseband part; and after linear modulation of the compensation signal, subtracting in an addition stage a resultant signal at an input of the receiver from a spurious coupling signal between the transmitter and the receiver, the transmitting signal having an auxiliary signal impressed upon a carrier signal from the RFID read/write unit with a frequency offset fd, for the purpose of processing without any DC voltage in the receiver downstream of an RX converter; wherein the input of the receiver comprises a turn-on and turn-off attenuation element which, when turned on, protects the radio frequency part against overdrive or against intermodulation in the RX converter so that weights can be ascertained for the copy of the transmitting signal and direct rejection of the coupling signal is achieved, the attenuation element subsequently being turned off and the RFID read/write unit changing to an operating mode and performing permanent readjustment of the transmitting signal suppression.