“Hands-free” access and/or engine starting system for automobile vehicles

Authentication device (1) for automobile vehicles (V1, V2) that controls door locking and/or engine starting and is able to interchange data over a certain distance with an identifier (3, 10-12), intended to be carried by a user, when said identifier lies within the emission/reception coverage zone of said authentication device, to enable control of a requested function including “hands-free” vehicle access and/or engine starting by corresponding determined actions of a user on the vehicle, when said identifier has been authenticated by said authentication device,

• wherein said authentication device (1) is connected to a single antenna (2) inside the vehicle passenger compartment (H) and is able to emit via said antenna at least two distinct emission powers,
• a first emission power enabling said antenna to cover a first zone (Z1, Z′1) including at least part of said passenger compartment (H), and
• a second emission power greater than said first emission power enabling said antenna to cover a second zone (Z2, Z′2) including at least the whole of said passenger compartment and a coverage zone outside said vehicle,
• for proximity detection of the identifier by interrogation of a location of the identifier in or outside specific zones according to said user's requested function and checking if the location of the identifier allows the requested function.