Modern vehicles are equipped with keyless entry systems operated through key ring remote controller. The centralized door lock system and the alarm system can be operated through the same remote. This system is used as a safety measure to protect the vehicle from theft and also useful to lock / unlock the vehicle from a distance of 25 meters or more. In the remote, a tiny chip generates codes which are transmitted as Radio frequency signals and the receiver in the vehicle responds to the codes and act accordingly.
The remote controller uses the Hopping code or Rolling code which can be used to create thousands of codes applicable to each vehicle. For each remote, a particular sets of codes is used which is applicable to only that remote. So the vehicle cannot be unlocked using another remote. When we press the button in the remote, the transmitter sends a bit code with a function code to perform a particular job such as lock, unlock etc.
The receiver in the vehicle is programmed to receive the particular codes of its transmitter and when it receives the desired code, it performs the function. All the doors, bonnet, etc are controlled through relay operated levers. The system uses battery power continuously to maintain its functions so that severe battery drain occurs. So it is necessary to start the vehicle daily even if it is not using. The Car alarm system uses a number of sensors like vibration sensor, leaf switches etc to wail the siren if there is an attempt of theft.
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