Abstract: The active transponder is intended for several applications or to operate in various modes requiring different levels of security. Security is controlled by varying the maximum communication distance to a reader. The active transponder includes a battery (2) powering the various electronic circuits amplifying component (8), a module (4) forming a demodulator for the incoming signals, and a component for validating the data comprised in the signals, and a data processing unit (10). The unit includes circuit (12) for controlling the maximum communication distance between the transponder and a reader transmitting signals at a determined power. Circuit (12) sends a security signal (S1, S2) respectively to the data validating component and/or to the signal amplifying component. This signal is used either to control the value of the reference value of the validating component, or to vary the gain of the amplifying component to vary the maximum communication distance.

Abstract: The active transponder is intended for several applications or to operate in various modes requiring different levels of security. Security is controlled in particular by varying the maximum communication distance to a reader. The active transponder includes a battery (2) used for powering the various electronic circuits. It further includes amplifying means (8), a module (4) forming a demodulator for the incoming signals and means for validating the data comprised in said signals, and a data processing unit (10). The unit (10) includes a circuit (12) for controlling the maximum communication distance between the transponder and a reader transmitting signals at a determined power. This circuit (12) sends a security signal (S1, S2) respectively to the data validating means and/or to the signal amplifying means. This signal is used either to control the value of the reference value of the validating means, or to vary the gain of the amplifying means to vary the maximum communication distance.