Reliable Motion Detection with Radar Sensors

With motion detection, a sensor detects a change within its detection range. This can then be used to determine the movement of a foreign object, because the measurement results are adapted to correspond to the movement. This is the basis for clearly identifying a movement and thus demonstrating the presence of a mobile object, vehicle, or person. Using this information and processing it as a digital signal makes it possible to trigger certain technical functions, such as the automation of security applications.

Challenging environments

The sensor technology has to tackle several challenges, because certain factors make motion detection more difficult. For one thing, the properties of the selected means of measurement impose limits in terms of functionality. For another thing, the environment of the object to be detected impacts the measurement result. The equipment’s intended use and task also play a role in determining how complex the motion detection is designed to be. The challenges vary depending on the selected measurement technology and application.
For example, PIR sensors have trouble with heat-insulating clothing or lasers and camera have problems with difficult lighting conditions. With ultrasonic sensors, on the other hand, drafts of air and thin covers also cause complications. Local conditions (complex structures and movable objects), high traffic volumes, irrelevant small animals, wind movements, and multiple people in the detection area place high demands on the equipment. The result is incorrect measurements or missing detections, which can affect the application’s efficiency.

Security-related Motion Detection

In the field of security technology, there are additional requirements. Here, motion detection serves as a protective measure. Deterring or alerting to a suspicious movement, for example, is meant to help prevent burglaries. In particular, reliability and measurement accuracy prove crucial for motion sensors used as security equipment. Criminal acts such as vandalism also increase the demands placed on the equipment’s quality.

Many Choices

The more sensor solutions and technologies are available, the harder it is to find your bearings. Companies have to consider which means of measurement is appropriate for their security application depending on the complexity of the task at hand and the environment in which the equipment is deployed.
There are several measuring methods used for motion detection, such as infrared (PIR), laser, or radar. The technologies utilise different means of motion detection. PIR detects motion based on a difference between the ambient temperature and body temperature, laser records changes in lighting, and radar employs electromagnetic waves, while ultrasound relies on the Doppler effect of sound waves to position objects. Video cameras can also detect motion using algorithms or integrated sensors.
For cost reasons, however, PIR sensors are most commonly used for simple applications. This might change now thanks to further developments in the field of radar technology.

Radar Technology

Radar technology is an excellent measuring technology for motion detection. In radar detection, an antenna actively emits high-frequency electromagnetic waves. If they hit an object, this results in the signal being reflected (as an echo), which the sensor then receives. The reflecting signals contain different information than before and can be used to conclude that a movement is taking place. Measurements are carried out continuously and in real time. Radar detects any change in moving people’s or objects’ positions. The radar-based data can be used as a digital trigger through appropriate signal processing.
This measurement method boasts several advantages compared to competing technologies:

• Radar waves are invisible to humans and pass through various materials, for example plastic. The measurement is carried out without contact, by a sensor that is integrated behind a plastic housing and goes completely unnoticed by the person generating the movement signal.
• This measurement method outputs only individual radar detection or object clusters. No visual image can be derived from this information, meaning that monitoring is carried out in an anonymous manner, ensuring data protection.
• Rain, fog, snow, wind, and ice generally don’t restrict the functionality of radar sensors. They reliably detect movement despite adverse weather conditions. Even extreme heat or cold don’t impair the technology.
• Radar sensors require no maintenance, and once they are configured, there is no need to check them regularly.
• The technology keeps working independently of lighting.
• Radar waves have long ranges. With this technology, large areas can be monitored and objects 150 meters away can be positioned, for example, with just one sensor. But the sensors are also suitable for close range.
• Radar boasts very good measurement quality due to its high resolution and extensive information collection. The technology provides precise and reliable measurement results for positioning objects and persons. The sensor solutions transmit data on speed, direction of movement, distance, and angular position.

More and more security equipment manufacturers are incorporating radar into their products. At the same time, the radar experts are managing to offer the sensors at more affordable prices. A very broad array of radar solutions is thus conquering the industry. Innosent already offers a wide range of radar motion detectors, providing the right solution for every application.
The various motion detectors can be used, for example, for lighting control in the garden or courtyard, but also in combination with simple alarm systems. A Tracking Radar application can be considered for more complex security monitoring from near to far.