Introduction

Detecting the presence of an object is crucial in the indoor environment for various use cases, such as modern smart homes, security systems, and industrial applications. Whether detecting a person in a smart home, assessing food quality in microwaves or fridges, or ensuring product quality in Industry 4.0, achieving high prediction and accuracy in object detection is essential for device efficiency.

Currently, many devices use PIR sensors to detect infrared radiation changes based on the temperature and shape of the object. However, Radar technology, which uses radio waves, is superior to PIR. In this blog post, we will compare the capabilities of PIR and Radar technologies to understand why Radar is emerging as the future choice for reliability and efficiency. 

Understanding of Sensors

Let’s delve into the specifics of each sensor to determine how to make the optimal choice for your needs.

PIR Sensor: The established choice

A Passive Infrared (PIR) sensor is a type of motion detector that detects infrared radiation emitted by objects within its range. By detecting changes in heat signatures from movement, it can recognize motion and subsequently signal its presence. It serves as a pre-filtering mechanism for security cameras, optimizing motion detection and resource usage. 

How does it work?
PIR sensors are made of pyroelectric material, divided into two halves that sense infrared radiation. The sensor is fitted with a Fresnel lens arrangement that enhances the sensor’s field of view by focusing infrared signals onto detection zones. When an object moves within the sensor’s range, it creates a differential change in radiation between the halves that indicates the motion of warm-bodied objects. These changes generate electrical pulses, which the sensor analyzes to distinguish actual motion from environmental fluctuations, ensuring reliable detection.

Radar sensor: Advanced technology

Radar (Radio Detection And Ranging) uses radio waves to detect and locate objects in the environment. Unlike the PIR sensor, it is an active sensing device with its own transmitter producing electromagnetic waves. Its applications vary with frequency: lower frequencies (MHz) are suited for long-range and adverse conditions, while higher frequencies (GHz) offer precise target identification and tracking.

How does it work?
Radar works on the phenomenon of Echo principle. The transmitter of the Radar emits electromagnetic waves that reflect back to the receivers when they hit a target. These received signals are then processed using Digital Signal Processing (DSP) to determine the target’s location, velocity, and direction. Radar calculates range by measuring the round-trip time of the signal, determines velocity through Doppler shifts, and finds angular direction from phase differences detected by different antennas. This provides real-time situational awareness for various surveillance applications.