The sensors are no good without an effective alarm. Alarm components are responsible for the visual and audible warning signals that a car has been compromised. They include:

Interior Light - activated to display intruder activity and may flash to create attention
Crossover Unit - a cross over unit picks up various sound frequencies, and sends certain frequencies to the car sound system.
Exterior Lights - external lights flashing are a common indication of alarm activation
Alarm Speaker - although car security systems generally come with their own horn speaker, more advanced systems can be wired into the car stereo system
Valet Switch – a hidden switch that allows valets to park the car without setting off the alarms.

A basic car alarm systems will sound the horn and flash the headlights.

Engine Immobilisers

Engine immobilisers can be fitted on their own, as part of a car alarm system or your existing car alarm system can be upgraded to include one. It is also important that the car alarm and engine immobilising systems are fitted properly to your car.

Remote Activation - Key Chain Transmitter

Most car alarm systems use a portable keychain transmitter to remotely communicate with the control unit to do things like locking and unlocking doors, turning on lights and setting and disarming the alarm or to manually set off the siren.

In most systems, the control unit will flash the lights and tap the horn when you arm and disarm your car. This lets you, and anyone in the area, know the alarm system is working.

More advanced systems have a central computer and built-in pager system. When an intruder disturbs your car, the central computer pages your keychain remote and informs which sensors were triggered. You can then return a signal to shut down the engine, effectively acting as a car key.

Alarm System Codes

For a particular line of transmitter devices, there are millions of different pulse codes to ensure your alarm system unique. Sophisicated car thieves can use code-grabbers to intercepts your "disarm code, and make a copy of your "key." using another transmitter. To avoid this, advanced alarm systems establish a new series of codes every time you activate the alarm. These rolling code algorithms mean a thief cannot use the code you previously used to arm or disarm to gain access to the vehicle.

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