Motion Sensors detectors are home security system essentials. While door and window sensors notify you if someone actively enters your home, motion sensors will alert you if someone is prowling in or around your home.
Though there are a few different types of motion detectors, most rely on similar technologies to detect intruders: they pick up on tiny changes—in things like temperature, vibration, or radiation—in the spaces they cover.
Several types of security devices use motion sensors. Some of the most popular forms include driveway motion detectors, motion-activated floodlights, exterior motion detector cameras, and indoor motion detectors.
You can use motion sensors to automatically turn on a light when someone approaches your home, sound an alarm when movement is detected in your living room, or trigger a motion sensor camera to start recording when someone enters your home.
Main Types of Motion Detectors
There are several types of motion-detecting technology—active ultrasonic and passive infrared (PIR) are two popular options, though microwave, tomographic, and dual-technology detectors also get some market share.
Active ultrasonic sensors emit ultrasonic sound waves that reflect off objects and bounce back to the original emission point. When a moving object disrupts the waves, the sensor triggers and completes the desired action, whether this is switching on a light or sounding an alarm.
Motion detection cameras, lights, and sensors used in home security systems generally rely on PIR sensors. These detect infrared energy, which humans and animals release as heat. If the motion sensor detects an increase in infrared energy, meaning someone has approached the sensor or walked within its range, it notifies the home security control panel and an alarm sounds.
PIR sensors can be set to ignore small changes in infrared energy, so they won’t trigger an alarm if the family cat or dog walks by or if the household temperature fluctuates slightly.
Some other sensors use a microwave or tomographic technologies, both of which emit waves of radiation—microwave and electromagnetic, respectively. When someone or something disrupts the radiation waves, the sensor sounds an alarm.
Dual-technology detectors are, as their name implies, sensors that rely on two different motion-detecting technologies to watch for movement. These are a bit more impervious to false alarms, as both technologies have to be tripped for the alarm to sound.
Installing Motion Detectors
As motion sensors have a limited range—anywhere from 50 to 80 feet—you’ll want to place several around your home, especially in areas where people frequently walk, such as hallways, staircases, living rooms, and bedrooms.
As a motion sensor may have a harder time detecting someone walking directly toward it, it’s better to place the device alongside a hallway where a burglar would walk parallel to it.
When deciding where to place each sensor, make sure they are at least 10 feet away from bright windows, radiators, and heating vents, as abrupt changes in temperature or HVAC-related airflow may trigger false alarms.
Motion sensors play a major role in any home security system, but with so many options available, it’s easy to feel overwhelmed. We’re here to help with our comprehensive guides to motion sensor lights and motion sensors.
What Is a Motion Sensor?
A motion sensor is a special device that notices movement within a specified range. This range can be around the detector or just in front of it, depending on what you choose.
These are usually used to notice any movement around our buildings and to scare off and illuminate whoever is creeping around at night.
Basic motion detectors notice objects in and around 6.5 feet to 70 feet. You can even purchase ones that detect further than that if needed. Types include optical, infrared, and radio wave motion detectors, which each come in handy for different situations.
A motion sensor (or motion detector) is the linchpin of your security system because it detects when someone is in your home when they shouldn’t be. A motion sensor uses one or multiple technologies to detect movement in an area.
When a sensor detects motion, it sends a signal to your security system’s control panel, which connects to your monitoring center. This alerts you and the monitoring center to a potential threat in your home.
The role of motion sensors in home security
The main purpose of motion detection is to sense an intruder and send an alert to your control panel, which alerts your monitoring center.
Sensors work when you’re not home or when you tell the system you are not there. You can even program some security systems to record events via a security camera when there’s motion.
Motion sensors stand guard, ready to react to various situations, such as movement in your living room, windows or doors opening or closing, or a window breaking.
Here are some common uses of motion sensors:
- Alert you in the event that your teen breaks curfew
- Trigger a doorbell when someone approaches the front door
- Alert you when kids enter restricted areas in the home, like the basement, workout room, or medicine cabinet
- Save energy by using motion sensor lighting in unoccupied spaces
- Notify you if pets enter areas where they’re not supposed to be
What Are the Various Types of Motion Sensors?
A conventional way to categorize motion sensors is by using the receiving and emission detection mechanisms as criteria.
Passive motion sensor alarms are based on infrared technology and only observe movements by passive heat detection.
Active motion sensors are based on radar technology. They work by transmitting, as well as by receiving radio waves that boomerang when hitting a moving object.
Combined motion sensor alarms use several technologies, but are not applicable to all areas. Some work better outside than others, and vice versa. Many access control systems use a couple of them to provide better protection.
Here is how are motion sensors commonly categorized:
- Passive infrared sensors (PIR). These motion sensor alarms sit with a bird’s eye view of the room and detect changes in the IR signature of a room over time.
- Active infrared sensors. Also known as tripwires, these emit an IR beam from one side of the room to the other, that detects an intruder when it gets interrupted. Active infrared sensors, while still being used for security purposes, are especially used in robotics and for proximity detection.
- Ultrasonic motion detectors. A different paradigm, these works by emitting ultrasonic sound waves to detect motion.
- Tomographic motion detectors. One of the coolest innovations in motion sensor technology, these are comprised of a mesh of radio detectors around a room that detect changes in the ‘fabric’ of the mesh caused by people moving through them.
- Gesture detectors. These are a subcategory of IR or camera motion sensor alarms that detect specific motions.
Hybrid motion sensors apply several technologies. Case in point, a motion sensor camera can be integrated into inside and outside access control systems, and the technology in use will depend on whether it is dark or light.
Types of motion sensors
Passive infrared (PIR)
Passive infrared sensors detect body heat (infrared energy) by looking for changes in temperatures. They are the most widely-used motion sensor in home security systems.
Optical Motion Sensors
An optical motion sensor is equipped with a light source that will illuminate a spot of light on something called the surfacer. When this light is reflected back to the lense and photosensors array, it will follow that target as it moves around in the specific field of view.
Infrared Motion Sensors
Infrared sensors can detect differentiation in heat (such as body heat) within the covered area. They detect the heat and turn on the light, security camera, and an alarm when any changes are detected within the spectrum.
Radio Wave Motion Sensors
Radio Wave, or “Radiofrequency”, motion sensors will cast out microwave signals to protect a room or building. When tripped, they will also turn on the light, security camera, and alarm if that’s the type you have. Your security camera will know the time that your alarm was set off and show you the corresponding images or video.
Where Is a Motion Sensor Used?
Motion sensors are very useful when they operate in conjunction with other devices like security alarms, lights, and security cameras. The most common use, in fact, is to catch trespassers around or within a home. These are also used for commercial properties.
These detectors, when used together with said devices, can successfully catch an unwanted guest before they get close enough to cause harm to the property or people within the property. Not only that, but the photos or videos taken by the security cameras can be used in court.
Motion sensors are also built into several new technologies these days, like automatic doors, certain smartphones, gaming consoles, robotics, and more. Today we’ll tell you about their security uses.
Security and Safety Lighting Systems
Motion detectors are used with lights or systems of lights for safety and security reasons. If a person walks by a monitored area the light will automatically turn on right away. Your security camera will catch that person in a photo or video.
Motion-activated floodlights are the most popular type of light used with a motion sensor. They’re used for security as they light up the outdoor area at night. You can have a system that activates all floodlights around your home and garage when only one sensor is tripped.
For safety purposes, these are helpful and convenient when walking outdoors to a destination in the dark, such as the garage, for example. It can save you money on energy as they’re only turned on as you’re detected. You can turn off the alarm system for these types of uses.
Occupancy sensors are used indoors to protect you and your family and detect any movement in the home or specified room.
The corresponding light will turn on if motion is detected, and it will turn back off when no motion is detected for a certain amount of time. These can save you lots of money each year, and companies are using these for the same purposes as well.
How Do Motion Sensors Work?
There are three main types of motion detectors, each playing a role in different security or safety situations. These three categories are active, passive infrared (PIR), and combined.
How do motion sensors work and what are the differences between the different types? How could each of these types benefit you?
These sensors have a mechanism that sends waves or signals across an area such as a room, etc. When the monitor senses a change in the response time of the wave, it is activated. These waves, as we mentioned above, can detect movement and respond extremely fast.
These can even detect branches moving in the wind depending on the sensitivity range set on the detector itself. You’ll have to adjust this range if you don’t want these small movements to activate your light or lighting system. This is the type of sensor used in shopping malls and other places to activate automatic doors.
A Passive Infrared sensor, also commonly known as a PIR sensor, is used to sense and detect motion. PIR motion detection lights will turn on whether the person or moving object is inside or outside of the range.
These are less expensive than active sensors, are easy to operate, and use less power than active sensors.
These are commonly built into gadgets and appliances in businesses or homes. They’re also known as “IR motion” or “Pyroelectric” sensors.
Also known as “Dual Technology” sensors. These will use multiple types of motion sensing technology at once in order to reduce false alarms. Both types of sensors would need to be tripped in order for the alarm or light to be activated. This narrows down the source, but they aren’t always perfect. So you may get a few false alarms along the way.
Less Common Types
These motion detectors are less commonly used, but are still worth discussing:
- Ultrasonic motion sensors reflect pulses of special ultrasonic waves off of moving objects
- Vibration motion sensors work by sensing even the smallest vibration in a room; you can make these yourself, however, homemade vibration detectors are unreliable
It’s best to stick with what is popular and proven to work reliably. Consistently when your safety and security are on the line.
Why Do I Need Motion Sensors?
Your entire property should have motion sensor coverage. So whoever or whatever is out there is promptly frightened away by the activation of your floodlights. If you have a large yard, they can be set up far away from your building. The authorities are notified before they get to your door or window.
Lights that are high-powered and on all night will take a lot of power. Resulting in huge electricity bills for you and your family. But normal floodlights are constantly on will create a lot of lumens, which means they’re very bright and energy-consuming. These could bother your neighbors at night if continuously on.
Outdoor motion sensor lights only come on when tripped. By using a motion sensor with your floodlights, you’re only paying for the lumens you need to use. In an emergency situation or when you choose to use them.
With solar-powered lights, you don’t have enough lumens to scare someone away. Plus they’re not going to work all night. To solve your problem, you’ll need something called a motion detector or motion sensor. This device will work in conjunction with your light fixture.
Stay Safe With High-Quality Motion Sensors
Now you know the answer to, “How do motion detectors work?” So, give yourself and your family peace of mind with the right one. Whether you choose a PIR sensor or an infrared sensor, or another type altogether. You can rest assured ADT will help scare off unwanted intruders.
Motion sensor security technologies have come a long way over the years and continue to be improved exponentially. Keep your home or business safe this year and into the future with new ADT home security sensors today.