What A Motion Sensor Is, How It Works And What It Detects

What A Motion Sensor Is, How It Works And What It Detects

The motion sensor is one of the most purchased home automation devices in recent years. Its potential and the many integration possibilities make it a competent and reliable solution.

There are several types of sensors on the market. Depending on its use, it is preferable to opt for one kind rather than another. 

The technologies with which it works are different; therefore, it is advisable to know them to make a purchase in line with your needs. The leading electronics brands offer high-quality products capable of making very precise detections. The latest generation sensors perform continuous monitoring, immediately transmitting any cases worthy of attention. This makes their use convenient and widespread on a large scale worldwide.

What Is A Motion Sensor?

More and more people feel the need to strengthen the safety of their environments, from home to office. Motion sensors offer great help in this regard. They are considered a valid alternative to protect your property, but their functions are manifold. For this reason, before proceeding with their choice, they must know the technology they use in detail. Apartment thefts have increased attention around this type of device, which explains the increase in sales. The bad guys’ protection is causing more buyers to choose state-of-the-art motion and sensor models. 

Their primary characteristic is identifying each type of movement in a specific periment. They are usually integrated with an anti-theft system and are installed to protect against unwanted entry by people or animals. Inside an office, a house, or a commercial space, there can be valuables that attract the attention of criminals and can put the safety of those who live or work there at risk. Consequently, by adopting one or more motion sensors, it is possible to optimize the operation of the burglar alarm systems and put off or discourage thieves.

How Does A Motion Sensor Work?

The advantages deriving from this type of device are due to its operation, which is very simple.

When a minimum volumetric movement is detected, the sensor triggers an alarm, which can be a visual or audible signal or both. The latter is captured thanks to a microwave and ultrasound sensor. In this way, a sort of “invisible barrier” is created at the entry points of the building, and the sensor is activated when a temperature change occurs, perceived by infrared rays.

Motion sensors can also be installed in transit areas such as corridors and inside bedrooms. To avoid false alarms, there are ad hoc programs that allow the inhabitants to move freely. The market’s motion sensors are brilliant and activated only when necessary. In this way, they can be used intelligently even if children or animals are in the building.

What A Motion Sensor Detects

Thanks to the technologies available, the sensors allow you to detect different things depending on their type. The main ones are two:

  1. PIR (passive infrared) technology is based on a pyroelectric sensor;
  2. Double technology (PIR + Microwave).

The first carries out an infrared detection of the body temperature. At the same time, the second also associates a microwave that transmits a signal to the control unit only when both detections of the temperature close to that of the body and a movement detected by the Microwave. 

This makes the second technology much more reliable and better in preventing alarm phases. Motion sensors can be insensitive to pets up to a certain mass (Pet Immune) or be sensitive to masking. In the second case, they immediately signal if the sensor lens or mirror is covered, preventing operation. Each sensor can be indoor or outdoor with different visual coverage and range of action, to be selected based on their application, location, and reliability.

Types Of Motion Sensors

The motion sensors can detect people’s presence in the environment in which they are installed to protect the doors and windows by activating an alarm. They can be used with perimeter sensors to obtain essential protection of the environments to be controlled. For this reason, installing them on any anti-theft system is always advisable. These sensors must be installed in transit areas. 

However, they can also be placed indoors. The alarm can be activated, in any case, thanks to a partial program that allows you to enable perimeter protection by excluding the internal motion sensors. 

This is done using the so-called “home mode, ” also called ” night mode,” which offers the possibility to move freely in various controlled places without sacrificing security. Motion sensors differ according to their type and detection technology. 

The classic or curtain motion sensor is mainly used to protect indoor environments, while the curtain one is more suitable for controlling gates. It is, therefore, a perimeter motion sensor. Based on the technologies used for detection, three types of motion sensors are distinguished:

  1. Infrared (PIR): this uses infrared light. Therefore, the device detects a change in temperature when a person enters the monitored area and triggers the alarm;
  2. Double technology (infrared + DMT): This combination of infrared + DMT, i.e., beam detection, minimizes the possibility of false alarms, ensuring very precise detections;
  3. Triple technology (infrared + DMT + MICROWAVE MW): This type of sensor uses three detection technologies and is also valid in cases where pets are present. With microwave detection, the sensor can detect the presence of a moving body in the controlled area. This results in a very high level of reliability and a meager false alarm rate.

Given its nature, the PIR sensor must always be positioned in an area far from heat sources and any element that involves changes in heat. Otherwise, the detections could be compromised. Therefore, places where air conditioners or radiators are present, should be avoided. Furthermore, installation in areas with objects that produce constant movements, such as aquariums, is not recommended. Sensing usually works best when moving from left to right or vice versa. Instead, it is less reactive if someone moves toward the sensors. Consequently, it is preferable not to place them in front of mirrors or windows to prevent infrared rays from bouncing off and causing false alarms.


The various types of motion sensor sensors ensure high effectiveness. This means excellent reliability of the devices in carrying out their functions. The small size of numerous models on the market also makes them not bulky and can be perfectly integrated into the overall furnishing of the room. In addition, models are also available with protection against atmospheric agents that guarantee excellent durability over time.

Also Read : Bluetooth Headset

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