How Car Alarms Work

Car alarms are an electronic device which is designed to prevent burglary and warn the owner if a theft attempt is being made. Usually a car alarm will output a high pitched sound when the system is triggered by vibration, close or open of trigger switches, sensing of small and fast change in battery voltage. Today's car alarm also monitors sensors like infrared, microwave, ultrasound or tilting of the vehicle in case of unauthorized towing. Some cars have alarm systems which send out SOS signal in case of breakdown or theft. Alarm systems are also incorporated with navigation system to increase the security of the car. If the car is stolen, it can be traced by an embedded navigation system. This functionality can also be used to locate lost cars in large parking lots by giving out a chirping sound.

Many times a car alarm can give out a false alarm when it feels vibrations of thunder or a passing truck. Sensors need to be adjusted properly otherwise it can trigger the device even when a person accidentally touches the automobile. There is an increase in the crimes related to theft of vehicles. For people who want security for their cars and want to avoid false alarms you can have a police tracking system installed, many newer cars have this tracking capability built in to the operation of the help/navigation system, like On Star. This system comes with an additional cost which is to be paid on a regular basis. Most alarm systems utilize a remote controller (key fob); this way a user can disable the alarm from a distance. The remote control feature is very convenient if the system is triggered by a false alarm. Key fob's can integrate a variety of functions, controllers that have the LCD option which can project the image of the part of the vehicle that is under threat by a thief is one example.

Source by: http://www.2carpros.com/how_does_it_work/car_alarm.htm