ACTIVE TRANSPONDER EQL PROVIDED WITH MEANS FOR MAKING MAXIMUM COMMUNICATION DISTANCE VARIABLE

摘要

PROBLEM TO BE SOLVED: To provide an active transponder operating in various applications or an operating mode for requesting a security of a different level. SOLUTION: Security is controlled by changing a maximum communication distance, in particular the distance to a reader. The active transponder comprises a battery used for supplying a power to various electronic circuits. The transponder further comprises an amplifying means 8, a module 4 for forming a demodulator for an arrival signal, a means for verifying validity of data contained in the signal, and a data processing unit 10. The unit includes a circuit 12 for controlling the maximum communication distance between the transponder for transmitting the signal via a predetermined power and the reader. This circuit is used to control a reference value of a validity verifying means or to change the gain of the amplifying means to enable an alteration of the maximum communication distance.