How Keyless entry is possible in Car? Tech Focus 10


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.

Both in the transmitter and receiver, Pseudo random number code generator is used. When the transmitter sends a bit code, it uses the pseudo random number generator to pick up the code and stores in the memory.

When the receiver gets the code from the transmitter, it also uses the pseudo random number generator to pick up the code. In this way, the transmitter and the receiver will be always synchronized so that the receiver opens the door only when it gets the code it expects. If the synchronization is lost through pressing the button continuously more than its codes, the receiver will ignore the transmitter and is necessary to synchronize the system again. The resetting method is different in different makes, so follow the procedure available in the hand book supplied by the manufacturer.

Receiver

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. The alarm system typically consists of

1. Sensors that can include switches, pressure sensors and motion detectors

2. Siren, often able to create a variety of sounds so that you can pick a distinct sound for your car

3. Radio receiver to allow wireless control from a key fob

4. Auxiliary battery so that the alarm can operate even if the main battery gets disconnected

5. Computer control unit that monitors everything and sounds the alarm

The brain of the alarm system is actually a small computer. Its job is to close the switches that activate alarm devices such as horn, headlights or an installed siren when certain switches that power sensing devices are opened or closed. Security systems differ mainly in which sensors are used and how the various devices are wired into the brain.

The Alarm system is wired to the car’s main battery, but they usually have a backup power source as well. This hidden battery kicks in when somebody cuts off the main power source .Since cutting the power is a possible indication of an intruder, it triggers the alarm

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