Abstract: A reader for identifying passive transponders includes an antenna for receiving a first signal (Tx) from the reader and for transmitting a second signal (Rx). The reader includes: a time base generating a sinusoidal signal, a control circuit, a modulator for transmitting to the control circuit data to modulate the sinusoidal signal so as to generate a signal carrying commands which, when it is received by the antenna of the transponder, forms the first signal (Tx), a demodulator, a decoder, a communication interface and an antenna. The demodulator, which is connected to the antenna to receive the second signal (Rx), includes two multipliers, one being of the inverter type, and an adder designed to combine the data derived from the multipliers. A system including first and second devices that communicate by way of a modulated transmitted signal is also described.

Abstract: A reader for identifying passive transponders includes an antenna for receiving a first signal (Tx) from the reader and for transmitting a second signal (Rx). The reader includes: a time base generating a sinusoidal signal, a control circuit, a modulator for transmitting to the control circuit data to modulate the sinusoidal signal so as to generate a signal carrying commands which, when it is received by the antenna of the transponder, forms the first signal (Tx), a demodulator, a decoder, a communication interface and an antenna. The demodulator, which is connected to the antenna to receive the second signal (Rx), includes two multipliers, one being of the inverter type, and an adder designed to combine the data derived from the multipliers. A system including first and second devices that communicate by way of a modulated transmitted signal is also described.

Abstract: The invention concerns a reader (10) for identifying passive transponders (12) comprising an antenna for receiving a first signal (Tx) from the reader and for transmitting a second signal (Rx). The reader comprises: a time base (54) generating a sinusoidal signal, a control circuit (64), a modulator (56) for transmitting to the control circuit (64) data to modulate the sinusoidal signal so as to generate a signal carrying commands which, when it is received by the antenna of said transponder, forms said first signal (Tx), a demodulator (58), a decoder (60), a communication interface (62) and an antenna (14). The demodulator (60), which is connected to the antenna (14) to receive the second signal (Rx), comprises two multipliers (76, 78), one (78) being of the inverter type, and an adder (70) designed to combine the data derived from the multipliers (76, 78).

Abstract: The invention concerns a radio-frequency transponder (12) for contact-free identification with a reader (10), comprising: an antenna (24), an analog circuit (25) including a capacitor (32) an AC-DC converter (34), a modulator (40) and a demodulator (38), a logic control circuit (26), a storage unit (27). Said transponder (12) is designed such that: the antenna (24) and the capacitor (32) form together a resonant circuit, the clock extractor (36) processes the first signal (Tx) to extract therefrom a clock signal addressed to said modulator (38) as long as the voltage of said signal (Tx) exceeds a first threshold value, the converter (34) transforms the first signal (Tx) into a rectified signal, to power the transponder (12). The performances of the transponder, and more particularly energy recuperation and data transmission rate, are improved by the fact that the analog circuit comprises two clock extractors, one of low level type (35), the other of the high level type (36).