Everything You Need to Know About Car Alarm Sensors
A car isn’t truly secure unless it has car alarm sensors. There are a number of different sensors available. They include:
- Shock Sensors
- Glass Breaking Sensors
- Microwave Sensors
- Motion Sensors
- Infrasonic Sensors
The first shock sensors featured a screw with a sharp pointed tip and a metal cup on a spring. The cup was located at the end of the tip of the screw. When the car was attacked, the vibration would cause the screw to move and make contact with the cup and it would trip the alarm. Later came shock sensors that monitored the vehicle in different ways. The piezo shock sensor included metal materials that adhered to each other, an electronic circuit and a processor. Laser or reflective shock sensors featured a light emitting diode or LED. A light from the LED would shine off of a reflective surface. As the reflective surface moves, the signal is analyzed and if the motion passed a pre-determined parameter, the sensor would trip. Infrared shock sensors included an infrared beam and the sensor tracked its movement. There were also electro-magnetic shock sensors. These sensors include a suspended magnet that moves in front of a coil when there is impact to the vehicle.
Glass breaking sensors were created to “listen” for the breaking of glass. It included a microphone and it sensed sound frequencies.
Microwave sensors bathe the interior of the vehicle with radio waves forming a bubble around the device. It would trip when it sensed movement within the bubble.
There were two types of motion sensors—one that featured a pendulum and one that included mercury. When the car was attacked, the vibration would cause the pendulum or mercury to move and trip the alarm.
Infrasonic sensors featured two microphones, one mounted inside the vehicle and one mounted outside. If there is an impact on, say, the window, then the window pushes in and causes a change in the air volume inside the car. The interior microphone measured the change in air pressure while the exterior microphone allowed the device to monitor air pressure outside the vehicle.
Today all these types of sensors are miniature computers and digitally measure changes. This assures that there are no false alarms as was the case when non-digital sensors were used.
Most alarm systems come with a glass breaking sensor or some form of shock sensor. However, each type of sensor has its own advantages and disadvantages. For example a glass breaking sensor may not be right if the owner of the car keeps the windows slightly rolled down. It also doesn’t work as effectively as designed in a convertible car when the top is down. Most alarm manufacturers include shock sensors in their alarms because they cover the car as designed under most circumstances.
Microwave sensors are ideal for covering the interior of a convertible vehicle and some styles of Jeeps. These sensors can be adjusted to cover a little bit of area around the exterior of the car and thus sense someone before they have even touched the vehicle.
The sensitivity of most sensors can be adjusted and even turned off via the remote.
