When it comes to motion sensors, they use various technologies to detect movement in an area and are used commonly in security, industrial, transportation systems. But there are many varieties when it comes to motion sensors like the PIR motion sensor, microwave sensor, ultrasonic sensors, etc.
Today, through this guide, we will be covering two commonly used motion sensors used today which are the microwave and PIR sensor and find out what are their differences, advantages, disadvantages and ultimately, which one to use for your projects.
Today through this guide, we will go through:
- Microwave Sensor
- What is a microwave sensor
- Advantages and disadvantages of using a microwave sensor
- Microwave sensor applications
- Example of Microwave sensor:
- PIR sensor
- Microwave Sensor vs PIR sensor
What is a microwave sensor?
Microwave sensors also known as Radar, RF or doppler sensors are electronic devices capable of detecting motion from walking, running to crawling in an outdoor environment by using electro-magnetic radiation.
It is able to detect motion by applying the Doppler effect and project microwaves which will bounce off surfaces and return to the sensor. It is able to measure and detect the amount of time for the signal to be reflected to the sensor which is known as echo time.
What is Echo time?
Echo time helps calculate the distances from any stationary object within the detection zone and establishes a baseline for the motion detector to work from.
With echo time, the sensor is able to detect if there is any movement in the detection zone as if a person is moving within the zone as the waves will be altered which changes the echo time. With the microwave sensor, it is able to do all this within less than a microsecond.
Advantages and disadvantages of using a microwave sensor
When it comes to sensors, they each have their pros and cons. So what are the advantages and disadvantages of the microwave sensor?
Not affected by ambient temperature
- Microwave sensors readings are not affected by its ambient temperature.
- This makes them a very versatile sensor and they can be in many various harsh environments including high heat, outdoors (exposed to rain, fog, wind, dust, snow, etc), etc.
Wide Detection Range and Velocity
- Microwave sensors waves are able to go through walls and holes which allows them to have a wide detection range.
- This allows them to cover a large area and also large outdoor areas.
Reduce False Alarms
- Microwave detectors can be programmed in a way to reduce the number of false alarms without reducing correct positives
- This increases accuracy and makes it simple to use.
Continuous Power Draw
- For microwave sensors, they require a continuous power draw which may be expensive to run
Works in interval
- For microwave sensors, they work only at intervals instead of continuously.
- If someone moves fast enough, there is a chance that they might be running fast enough which allows them to potentially evade detection.
Microwave sensor applications
With Microwave sensors, due to their characteristics, they are applicable in many scenarios and environments like:
- Industrial (eg. Liquid Measurements)
- Civil Applications (eg. Measuring Vehicle Speed)
- Transportation (eg. Reverse car alarm)
- Security (eg. Anti-Burglar Systems)
- Automated Door / Lights
Example of Microwave sensor
Now we know how the Microwave sensor works, its advantages and disadvantages and also its applications, it is time to get one! How about our MW0582TR11 – 5.8GHz Microwave Doppler Radar Motion Sensor!
MW0582TR11 – 5.8GHz microwave doppler radar motion sensor is designed by Maxustech company. This doppler radar is a microwave module that can transmit the electromagnetic wave of 5.8GHz. It can detect the difference between the transmitted wave and reflection wave to judge whether there is an object moving over the doppler radar.
In order to get the accurate data from the sensor, this Doppler radar motion sensor has a self-made patch antenna which has a good antenna directivity. Moreover, this kind of doppler radar has an MCU inside which include intelligent algorithm to avoid noise gain caused by the device itself. It can also tell apart the environment effect such as moving branch and would not cause false-alarm thanks to the algorithm.
Is this microwave sensor easy to use?
Of course! This doppler radar not only has a sharp “eye” to detect the moving object but it is also easy to be developed because of its UART interface. As a matter of fact, this Doppler radar can be simply plugged into your Arduino board or Raspberry Pi through the serial port. Or you can just use a TTL to USB converter module to connect with your PC to read the data.
Here is a demo when using Python SDK if there is any moving object in front of the microwave sensor:
What is a PIR sensor
PIR sensor which is short for passive infrared sensor works by detecting the presence of heat energy in confined spaces by measuring infrared light radiating from objects in its field of view. It has the same core technology found in thermal imaging devices, night vision equipment, etc.
Technically, PIR is made of a pyroelectric sensor, which is able to detect different levels of infrared radiation. When a difference in temperature is detected by one of its beams, the sensor will be activated. Vice-versa, when all the beams detect the same temperature again, the sensor will be deactivated.
An example of this will be when a person walks in an enclosed room, heat signatures changes which activates the sensor and when the person walks out, heat signatures revert to its normal state and deactivate.
Because of this characteristic, they are suitable to use in enclosed spaces and also space that is constrained by walls, barriers or large objects.
Wish to find out more about the PIR sensor? You can check out our other blog on PIR Sensor introduction and How PIR motion sensor works with Arduino and Raspberry Pi!
Advantages and disadvantages of using a PIR Sensor
Similarly to the Microwave sensor, the PIR sensor has its own pros and cons. They are:
Consume Less Energy
- When it comes to PIR sensor, they consume less energy (0.8 to 1.0W) compared to microwave sensors.
- PIR sensors are able to detect motion reliably indoors despite the time. It works well in the day and in the dark.
- Compared to microwave sensors, PIR sensors are slightly cheaper.
- Compared to microwave sensors they are sensitive to temperatures and are easily affected by ambient temperature whereas microwave sensors are not affected.
- As they sense heat signatures, if the enclosed space is warm too (eg. in summer), it may not be able to detect any motion from humans as they are unable to sense any heat signature change.
- For PIR sensors, they are unable to operate at temperatures greater than 35 degrees.
Lower Detection Range and Coverage
- PIR sensors work effectively in Line of sight situations (down a walkway) but if they require movement across infrared beams like corner regions, it may face issues.
- PIR sensors also have to be installed in enclosed regions to be effective compared to microwave sensors with a wide detection range.
PIR sensor applications
Due to PIR sensor characteristics, they are suitable for applications in:
- Indoor and enclosed spaces (eg. Homes, Offices)
- High-Ceiling Areas
- Spaces with Airflow (eg. Walkways, hallways.)
- Places with direct line of sight (eg. Warehouse aisles)
- Life lobbies
- Common Staircases
- Places not affected by the outside temperature
Example of PIR sensor
Now we know how the PIR works, its advantages and disadvantages and also its applications, here are some examples of the PIR sensor:
This Grove – PIR Motion Sensor(Passive Infrared Sensor) can detect infrared signal caused by motion. If the PIR sensor notices the infrared energy, the motion detector is triggered and the sensor outputs HIGH on its SIG pin.
The detecting range and response speed can be adjusted by 2 potentiometers soldered on its circuit board, The response speed is from 0.3s – 25s, and max 6 meters of detecting range.
The Grove – PIR Motion Sensor(Passive Infrared Sensor) is an easy-to-use motion sensor with Grove compatible interface. Simply connecting it to Base Shield and programming it, it can be used as a suitable motion detector for Arduino projects.
Grove – Adjustable PIR Motion Sensor is an easy to use Passive Infrared motion sensor, which can detect infrared object motion up to 3 meters. Any infrared object moves in its detecting range, the sensor outputs HIGH on its SIG pin.
With this PIR motion sensor you can adjust the SIG HIGH time up to 130s via the potentiometer, moreover, you can adjust the detection range via the other potentiometer.
Microwave Sensor vs PIR sensor
This is the finale that we have been waiting for. The microwave sensor vs PIR sensor! So which Arduino motion sensor should you use for your projects?
Well it depends on your project needs and environment!
The microwave sensor is perfect if you have a large space and area with awkward spaces like corners such as your driveway or garden while the PIR sensor is perfect if you have an enclosed space and spaces with a direct line of sight with airflow such as hallways and walkways.
When it comes to the environment, PIR sensors are easily affected especially when it comes to temperature. PIR sensors can only work in conditions under 35°C while a microwave sensor is hardly affected by ambient temperature.
A microwave sensor is able to offer stable performance at temperatures as low as -20°C and as high as 45°C!
Continuous or slotted detection zone
Microwave sensor features a continuous field of detection zone while the PIR sensor has a slotted detection zone. This may cause the PIR sensor to miss out on objects which makes microwave sensors better in security applications compared to PIR sensors.
When it comes to energy consumed, microwave sensors consume more energy compared to PIR sensors. PIR sensors consume about 0.8 W to 1.0 W of electricity while microwave sensors consume about 1.1 W to 1.5 W.
When it comes to sensitivity, the microwave sensor has a much high sensitivity than the PIR sensor.
Now that you have found out which Arduino motion sensor to use for your project,
You can get them now to get started with your project!