A power management circuit for a system that has combined power supplies from an inductively coupled circuit and from a battery comprises voltage sensing circuitry for sensing the voltage of each of the power supplies. A switching arrangement selectively c...

The invention relates to a procedure for the authentication of a first transceiver unit with respect to a second transceiver unit, located at a distance to it, whereby by means of the first unit a first signal is transmitted via an aerial connected to it; ...

The method for enabling authenticated access of an individual (10) to a security area (12) by means of a transponder (14) carried by the individual which on receiving an interrogation signal outputs an ID code group, and a control unit (18) located in the ...

A security system to prevent unauthorised starting of the engine of a vehicle, comprises a remote control unit (18) equipped with a transponder which, on reception of an interrogation signal by means of at least one reception aerial (20), transmits an iden...

A security system to enable access to a protected area, comprising a remote control unit (22) with a transponder (28), carried by an individual, which transmits an identification code on reception of an interrogation signal. A control unit, located within ...