Method for ultra high frequency continuous communication with and location of a portable device for “hands-free” access to a motor vehicle

A system for ultra high frequency communication with, and location of, a portable device for “hands-free” access, the system comprising an ultra high frequency locating device on-board a motor vehicle and comprising:

• an electrical power supply source;
• an ultra high frequency transceiver, comprising a printed circuit connected to:
• an antenna by a first communication line;
• a computer;
• the ultra high frequency locating device further comprising:
• a second communication line, wherein on the second communication line, at least one attenuation module, located at a predetermined distance from the transceiver, comprising a switching means, and an impedance of predetermined value, is connected to ground;
• means for controlling the at least one attenuation module;
• means for determining the location of the portable device, electrically connected to the transceiver and to the means for controlling the attenuation module;
• the switching means having:
• a first position, in which the transceiver is disconnected from the antenna and is electrically connected to the impedance associated with said switching means via the second communication line;
• a second position, in which the switching means electrically connects the transceiver to the antenna via the first communication line;
• wherein the computer is configured to alternate the switching means between the first position and the second position according to a predetermined ratio between an activation duration of the first position and an activation duration of the second position, to establish at least one dedicated data channel between the motor vehicle and the portable device.

A system for ultra high frequency communication with, and location of, a portable device for “hands-free” access, the system comprising an ultra high frequency locating device on-board a motor vehicle and comprising:

• an electrical power supply source;
• an ultra high frequency transceiver, comprising a printed circuit connected to:
• an antenna by an electric power line;
• a computer:
• the ultra high frequency locating device further comprising:
• on the electric power line, at least one attenuation module, located at a predetermined distance from the transceiver, comprising a switching means, and an impedance of predetermined value, is connected to ground;
• means for controlling the at least one attenuation module;
• means for determining the location of the portable device, electrically connected to the transceiver and to the means for controlling the attenuation module;
• the switching means having:
• a first position, in which the transceiver is disconnected from the antenna and is electrically connected to the impedance associated with said switching means;
• a second position, in which the switching means electrically connects the transceiver to the antenna;
• wherein the computer is configured to alternate the switching means between the first position and the second position according to a predetermined ratio between an activation duration of the first position and an activation duration of the second position, to establish at least one dedicated data channel between the motor vehicle and the portable device,
• wherein, after the at least one dedicated data channel is established between the motor vehicle and the portable device, and a connection on the dedicated channel is kept active, the system is also configured for:
• the motor vehicle to send, over at least one predetermined frequency, at least one status request message to the portable device and for the motor vehicle to receive at least one status confirmation message from the portable device;
• and
• for the portable device to receive the at least one status request message and for the portable device to send the at least one status confirmation message to the motor vehicle in response to receiving the at least one status request message, and
• wherein the motor vehicle is also configured to send the at least one status request message in a frame selected between an advertising frame and a data frame.