Vehicle Security

Car Security Guide- Part II

When we talk about installing car alarm sensors, it's like installing 'eyes' and 'ears' into the car alarm brain to assist the module/car alarm brains to look after our car. As the name implied, the job of a sensor is to sense any break-in attempts by the auto-theft. Different type of sensors have different functions, for an example a shock sensor will only senses any vibration/shock and send the signal to the alarm brain to trigger the siren. Sensors can be categorized into 2 types, a single stage/zone sensor or a dual stage/zone sensor

• Single stage/zone sensor
  Single stage/zone sensor will not give a warning chirp when it senses some break-in attempts by auto-theft. It will trigger the full blaring of siren when it senses there is any break-in attempts by the auto-theft to the certain degree/severity.
• Dual stage/zone sensor
  Dual stage/zone sensor refers to the ability of the sensor to respond in 2 different way, it depends of the degree/intensity/severity of the violation sensed by the sensor. For an example, a shock sensor will give a warning chirp when it sense a soft vibration but when a strong vibration is detected, it will set the alarm to have full blaring of siren. This is good to serve as some kind of warning to potential auto-theft to warn them off. The alarm warning chirp, serve as the purpose of telling a potential thief that the vehicle is protected with an alarm too.

Type of Commonly Used Sensors

Door sensors
Door sensor is just a switch built-in to your car. Most modern car such as our WAJA is pre-installed with the door sensor/switch. The main function of the switch is to switch on your dome light, reading light or courtesy light when any of the door/hood/trunk is not closed properly. The switch mechanism works like those refrigerator light switch. Most car alarm systems utilize the switching mechanism that is already built into the doors as the door sensor. When the door is closed, it presses the door switch, which opens the circuit. When the door is opened, the door switch is in the 'closed circuit' state where it'll switch on your dome light, reading light and courtesy light. At the same time, the door switch/sensor will send signal to the alarm brain/module to trigger the alarm siren to full blaring. There is no dual zone/stage door sensors, only single zone/stage. A trigger on the door sensor will set a full blaring of the alarm siren.
Actions that will trigger the alarm: Open the door

Shock sensors/Impact sensors
The function of the shock sensor is when somebody hits, kicks, jostles, moves your car or any attempt of break-in by the auto-theft that creates vibration, the sensor sends a signal to the alarm brain/module indicating the degree/intensity/severity of the motion. Depends on the type of shock sensor you are using, if it is the single zone/stage shock sensor, the alarm will trigger the siren to full blaring when the vibration has exceeded a certain degree (Sensitivity is normally adjustable). If it is the dual zone/stage shock sensor, it depends on the severity of the shock. The brain signals a warning chirp/horn/beep or sounds the full-scale alarm according to the intensity/severity of the impact/vibration.
Actions that will trigger the alarm: Knocking/Hitting any body parts of the car, Breaking the windows glass, Remove the wheel/tyre (May or may not, depends on the degree of vibration and sensitivity of the sensor), Jack the car up to be towed away (may trigger if during the processing of jacking up the car, it creates enough vibration).

Tilt sensors/Anti-lift sensors/ Anti-tow sensors
When an auto-theft comes with a tow truck, they can just lift up your car and tow your car away without breaking your window glass or hotwire. To protect your car against those tow truck auto-theft, you need a tilt sensor. The main function of a tilt sensor (or sometimes it's called Anti-lift sensor, Anti-tow sensor or even motion sensor) is to detect a difference in the level of your vehicle (measured in degree). If someone tries to jack the car up, the level of your car will change and this will trigger the alarm siren.
Actions that will trigger the alarm: Jack up the car

Glass break sensors/Glass tampering sensors/Windows Sensors/Audio Sensors
Main function of this sensor is to detect frequencies produced by breaking glass. The built-in crossover circuit will filter the frequencies received. The sensor will ignore any other sounds except when it detects the frequencies of the breaking glass, it will trigger the alarm siren.
Actions that will trigger the alarm: Breaking the glass

Perimeter Scanner/Sensors
ost of the perimeter scanner/sensor is actually a basic radar system. It will monitor what happens within its perimeter. The perimeter scanner/sensor consists of a transmitter and receiver. The transmitter sends out signals and the receiver monitors the signal reflections that bounced back. Based on this information, the perimeter scanner/sensor can detect any attempts of break-in or any intrusion. The radius of the monitored perimeter is adjustable, or its sensitivity is adjustable. For a dual zone Perimeter Scanner/sensor, when the outer zone violated, the alarm will give a warning chirp. When the inner zone is violated or any intrusion detected at the inner zone, the alarm will set the siren to have a full blare. Some example of the Perimeter Scanners/Sensors are:- Proximity sensors, Microwave sensors, Ultrasonic sensors, Radar Sensors.
Actions that will trigger the alarm: Going too close to the car (warning chirps, depends on the sensitivity setting as well), Someone enters into the passenger/driver compartment or cockpit.

Prepared by MrNiceGuy

Car Security Guide- Part I