What is the difference between a PIR and a microwave sensor? A motion sensor can use microwave or PIR sensors and here we briefly look at the pros and cons and differences.
What is a motion sensor?
A motion sensor is, as the name suggests, a device that can be used to detect when someone is approaching, so that, for example, lights are turned on when they are needed. They can be used to reduce energy bills by turning off lights when no one is around, or motion sensors can be used as a security measure, turning on lights and alerting a smart app when someone approaches, for example by flashing a light inside.
What is the difference between a PIR and a microwave sensor?
So there are motion sensors on the market that use microwave and PIR sensors, but what is the difference between PIR and microsensors?
PIR motion sensor
PIR = Passive Infrared
PIR sensors detect heat. They do this by measuring the ambient temperature in a room using a series of infrared beams. When even a single infrared beam detects a temperature difference, the sensor is activated and turns on the lights. When all infrared rays see the same temperature, the lights go out.
Microwave motion sensor
Microsensor, or Microwave. Do not mix with the microwave, as this will not heat the food.
These motion sensors transmit microwave signals and measure the time it takes for the signal to be reflected back to the sensor. The reflection is called an echo.
The echo time is used to calculate the distances to all stationary objects in the detection zone. This allows a baseline to be established against which to compare. A person entering the detection zone causes a disturbance in the microwave signal, which changes the echo time and turns on the lights.
History of motion sensors
Who invented the motion sensor and when did they become widespread? Motion sensor technology has been developed on the basis of radar technology,
PIR History
The basis of the passive infrared sensor (PIR sensor) was invented in the 1950s, but its use only became widespread in the 1980s, when Marcel Züblin patented it as the first consumer product to use motion-activated lights. PIR sensors are widely used in security systems, lighting and other applications where motion detection is required.
History of the microwave sensor
Microwave sensors were initially used mainly in military and security applications, but later their use has expanded to other applications such as automatic doors, camera systems and motion sensors.
The invention was also born in the United States, where Samuel Bagno was the inventor of the micro-analogue sensor. He invented the first motion sensor in the 1940s, using technology developed during the Second World War. Using his military knowledge of radar, Bagno developed a device that used ultrasonic waves and the Doppler effect to detect movement in a room. He exploited the device in the 1950s by developing the first burglar alarm
If you are more interested in the history of motion sensors, you can read more about the history of motion sensors here.
PIR vs. microwave sensor – functional differences
When choosing a motion sensor, you should consider the following:
| PIR | Microwave | |
| Sensitivity | Sensitivity poor in hot weather | Consistent detection at all temperatures. |
| Coverage | 90° | 360° |
| Observation | Not always detected if you walk straight towards it | Works even through the wall |
Because the PIR sensor uses thermal differential to detect movement, the ambient temperature can have a major impact on sensitivity. This limitation must be taken into account if you are looking for motion sensors for outdoor lighting. Extreme outdoor temperatures can have a significant impact on the efficiency of equipment.
On the other hand, microsensor sensors can be a problem in smaller indoor spaces, because they can detect movement through walls They can be problematic if there is a children’s room on the other side of the wall… Of course, the problem can be circumvented by installing a microsensor in a box.
A motion sensor is often much more
Motion sensor + twilight sensor = light only comes on in the dark
Virtually all motion sensors on the market also have a light sensor. In other words, the motion sensor is also controlled by a photocell, which, thanks to its easily adjustable settings, can be changed to respond to different lighting levels according to the desired use.
The light sensor is designed so that you can adjust the screw so that the motion detection is always on even when it’s light out or only when it’s dim or dark. This saves energy and therefore money for the end user.
Sensitivity adjustment in microwave sensors
Microwave sensors also usually have a sensitivity control to reduce the risk of detection through walls. It can be a dipswitch or a continuously variable control.
You can access the full range of motion sensors here.
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