Car
Alarms
are usually suitable for all cars equipped with 12V voltage and
a negative ground. Ones that are remotely controlled use RF communication,
protected by a FLOATING digital code and by an ANTI-SCAN feature.
Some alarms come with built-in ultrasonic and vibration detectors.
Usually, arming and disarming of the system is confirmed by the
turn indicators blinking and by a siren chirp. While the ignition
key is on, the system can not be armed. This protects the car
from having the alarm accidentally activated while driving. A
visual warning of the presence of the alarm is provided by an
LED indicator.
Depending
on the type of alarm, door lock outputs allow the central locking
system to be controlled by the remote control (programmable output
pulse duration). A signal to close electrically powered windows
is also offered. A built-in current sensor will trigger the alarm
if any electrical equipment is switched ON while the alarm is
armed. The current sensor activates 10 minutes after arming. This
prevents the cooling fan from triggering the alarm. Arming of
the current sensor is optionally selected when arming the car
alarm, and can also be disabled completely in the setting mode.
A built-in
ultrasonic detector can protect the passenger compartment. It
detects any movement in the protected airspace. When the alarm
is not armed, the ultrasonic generator is turned off. This protects
the passengers from unnecessary ultrasonic bombardment. Arming
of the ultrasonic sensor is optionally selected when arming the
car alarm.
A good built-in
vibration detector has a digital filter which can provide immunity
to false alarms. This detector has selectable functions for warning
or alarm triggers. Arming of the vibration detector is optionally
selected when arming the car alarm.
An automatic
Dome light control is provided by an extra door switch input/output
(negative trigger). It turns ON the dome light after disarming
and the opening of any door. The light will remain ON until you
switch ON the ignition (max. 60 sec.).
Typically,
when the armed system is triggered, there can be two different
reactions. Warning - a short siren and blinkers signal (0.5 sec.)
or ALARM - siren sounds for up to 30 seconds and the turning indicators
flash for 60 seconds. Panic alarms can also be triggered by remote
control.
A built in
powerful immobilizer can also disable important systems (starter,
ignition, electrical fuel pump etc.).
Car alarms
can be confusing. Here's a list of things to consider when shopping
for one.
Security
Features
- How long
does the car alarm sound for?
- Do the
indicator lights flash when the car alarm goes off?
- Is there
a flashing LED to deter potential thieves?
- Does it
come with warning stickers?
- When arming
and disarming the alarm does the siren beep and if so can it
be switched off?
- Does the
unit come with two antiscan remote controls? (very important
as it stops the thief copying and retransmitting the code to
your car)
- Is there
any form of interior protection should someone enter through
a window?
- Are the
doors, boot & bonnet covered by the alarm?
- Does the
car alarm have a vibration detection device (generally this
should be turned down to a minimum or switched off to avoid
false alarms)?
- Is the
car alarm capable of immobilizing the vehicle (i.e. stopping
the starter or the fuel system or the ignition from operating)?
- Does it
have a battery back-up siren?
- What kind
of warranty comes with the alarm?
- Is there
an override feature (should the unit fail or the remote control
cease to function)?
Modern cars
are getting more and more difficult to steal, which is causing
a problem with a new type of car crime called car jacking. Basically
the only way a thief can get your car is to apprehend you when
you’re in possession of the vehicle keys. Again some modern
alarms come with anti-carjack features which when a door is opened
a hidden switch inside the vehicle must be operated or the alarms
system will cut in and the car will be immobilized.
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