système d'alarme passif à ultrasons

OBS: Anti-Theft Standards. Definitions. Passive: An anti-theft device or system which is activated automatically when the operator removes the ignition key and leaves the vehicle.
OBS: Whenever a person needs help he can send an alarm signal ... by pushing a button on a miniature bodyworm transmitter. These alarm systems are called ""active"" alarm systems because an action is necessary from the person in need. However, there are situations in which the person in need is not able to activate an alarm. For that reason there is a need to develop an alarm system which automatically monitors the [situation]. The alarm system must detect an alarm signal automatically.