A high end home security set up may involve one or more components (video surveillance, electronic locks, and alarms). And usually, a burglar cannot make his way past so many obstacles. But if, some of these security components were inactive due to some reason and the burglar is able to make his way into your home, then he definitely cannot get past the motion detector. Motion detectors are sensors that detect movement in its path. They are often combined with cameras and lights to enhance their effectiveness and also to provide an added security blanket. If a motion detector is installed in your home while you are asleep and there is movement in the home, then it can be customized to trigger an alarm.
It can even be customized to switch on the lights or to activate a video surveillance system. Motion sensors can also be installed in your lawn, by the pool or even near your garage. But what if my pet is moving around the home? Will the alarm be triggered even then? No. There are different types of motion sensors which are apt for different locations around the home. While some of the models are ideal to be installed outdoors, there are other specific models that detect only human movement and are ideal for indoor installation. Let us take a look at some of them.
Types of motion sensors
Driveway Motion Sensor: The driveway motion sensor is used to detect large and metallic objects (typically vehicles) in and around your driveway. The IR beam can detect movement up to 80 feet away and then alert you according to the security settings chosen by you. The receiver can be placed within your home or just about anywhere that you choose. However, there have been cases where a large animal has caused a false alarm and hence, driveway motion sensors are equipped with a driveway probe. This probe is buried at the base of the driveway and only detects vehicles. Driveway motion sensors are usually combined with external locks and intercom systems. Once the motion sensor detects a vehicle, it locks the gate by itself and the intercom system gets activated. This way, you can verify the identity of the person before letting him in. Driveway motion sensors are the commonest of them all.
Recessed lighting motion sensor: Lighting motion sensors are extremely popular for their versatility and their effectiveness in preventing burglary attempts. Picture this - A burglar is sneaking around your home and suddenly all the lights in the lawn come on and an alarm sounds. He will make a frantic and desperate attempt to escape thereby ending any chances of a burglary. Also, he will be extra cautious to avoid entering the same house again. The recessed lighting motion sensor uses the PIR (Passive Infra red) technology that requires both heat and motion in order to be triggered. This filters out any false alarms that may be caused by movement of trees and pets. Also, these motion sensors can also be used in areas within your home. The lights will automatically switch on when motion is detected and switch off when no body is in the room.
Microwave motion sensors: These are among other types of sensors that detect movement and then send a signal back to the receiver. The system emits microwave energy that completely fills the area of detection and any disruption in this field of energy triggers an alarm. Contrary to what most people feel, microwave motion detectors do not harm human beings. No, the microwaves emitted are not going to cook or burn you. Typical models contain a gun diode that emits energy in the X range. A microwave motion sensor may either be bi static or mono static. (the transmitter and receiver in one unit or separate ones). Microwave beams cannot penetrate through metal and hence, the presence of any large metallic object in the area of detection creates a dead zone behind it. Any object behind the metallic object is undetected. On the other hand, if there are no metallic objects, then microwave motion sensors can even detect movement behind walls. Microwave motion sensors have a notorious reputation for triggering false alarms though. Even fluorescent lights which emit detectable light particles can trigger these systems. Hence, one must be extremely cautious while installing these systems at home.
Ultrasonic Motion sensors
The ultrasonic motion sensor detects movement using sound wave technology. The sensor emits a sound wave that is beyond the capacity of human ears and any disruption in this sound wave, triggers an alarm. There are two types of ultrasonic sensors, active and passive. Active sensors are the ones that emit sound waves while passive sensors only have a receiver that listens to sounds. Ultra sonic motion sensors are amongst the most sensitive type of motion sensors and hence, they are also the most expensive of them all. Ultrasonic motion sensors can cover a distance of up to 40 feet and any point within this coverage area falls within its detectable range. The detection however, weakens as the distance increases. Passive sensors are more of a sound detection unit, as they look for sounds like glass breaking or metal striking metal. However, since burglars are known to avoid making such sounds, most people use these sensors in conjunction with a Passive Infrared sensor.
While ultrasonic sensors are known for their efficiency, they also have their own share of disadvantages. Highly sensitive models are known to trigger false alarms even when an insect passes by in the field of detection. Even a strong gust of wind or a vibration caused by an airplane passing overheard is enough to trigger off an alarm. These sensors cannot pass through solid objects and hence have several dead zones in their detection area (incase of a fully furnished room). If you have a passive detector and the phone rings in the middle of the night, then be prepared for the wail of the siren.
Passive Infrared Sensors: These are the most commonly used motion sensors to detect movement. They detect heat emitted from animate forms. Now since all living things emit heat, a passive infrared sensor has a method of recording measurable changes in a specific area. This is then used to detect any unauthorized intrusion. If the unit senses or detects any changes in the temperature in its area of detection, then it immediately signals a processor which then analyzes the temperature change according to the set parameters.
If the change falls outside, then the processor instantly sends a signal to the alarm which is triggered. PIR sensors are ideal for indoor installations. Unlike ultrasonic sensors, they do not emit any kind of energy or signal. It consists of a lens which captures heat emitted from any living object and then captures and relays this to a solid state chip on a circuit board. It is this chip that records any changes. There are a wide range of lenses or mirrors that are available for different situations. For example, there is a lens that omits floor level movements. So if you have a pet that moves around in the home, the alarm will not be triggered off. The PIR motion sensor is amongst the most efficient and cost effective ones. They are also smaller and easier to install making them a perfect choice for home security.
The detection range for these sensors begins at the central point where the unit is located. So there are bound to be many gaps in the detection area. So, in high security areas, people use a combination of PIR sensors with microwave sensors to comb the detection area. It is also not a bad idea to install these sensors on the ceilings as they can provide a complete 360 degree view of the area. Since PIR sensors are highly sensitive to heat and cold, you should always be careful about the place where you install it, to prevent false alarms. It should not face heat vents, open windows (as the sunlight may trigger an alarm) or face wind or air conditioning vents. If the coverage area includes areas where the sensor may counter frequent temperature change, then special modifications may need to be made to avoid false alarms. Most companies offer a special tape to cover these areas.
Tips for Buyers
So you see, there are hundreds of models of motion detectors available in the market. You should always consider the size of your home, your budget and the kind of security you are looking for, before making your choice. Here are some tips if you are looking for motion detectors for your home.
- What is the level of security that you are looking for? Is it highly sensitive? Or will even, moderate sensitivity towards movement serve your purpose? Consider this as one of the most important factors that will determine your purchase.
- Do you have kids or pets at home? Then you would want to consider buying models that omit ground level movement.
- If you are planning to install the sensor outdoors, then it is a good idea to hide it to prevent any vandalizing attempts. Alternatively, you might combine it with other security systems like CCTV cameras and lighting systems.
- Always create a list of about 5 models and then compare amongst them. Choose a model that offers you the best of features at the most competitive rates.
- If you are unsure about which model to choose, then always consult the security company before choosing one. They will be glad to help you with suggestions and ideas.
