With the advent of the global wave of intelligence and the era of carbon neutrality, human sensing has been widely used in smart lighting, smart home, smart home appliances, smart security, and various IoT scenarios.
As the core technical solutions of intelligent sensing, radar technology and PIR technology, what are the characteristics and differences between them?
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Radar comes from the English RADAR (Radio detection and ranging) that is "radio detection and ranging". It is to obtain the distance from the target to the electromagnetic wave emission point, the distance change rate (radial velocity) by irradiating the target with electromagnetic waves and receiving its echo. ), bearing, altitude, etc.
Working principle：For details, please refer to another article of this public account《Radar principle》
PIR Pyroelectric infrared sensor: referred to as PIR (Passive Infra-Rey)
Composition：It is mainly composed of shell (Fresnel lens) + pyroelectric probe (filter + pyroelectric element PZT + field effect tube FET) + signal amplification processing unit.
Working principle：At 37°C, the human body emits about 10μm of infrared light, which is enhanced by a Fresnel filter and concentrated on the infrared sensing source. Infrared induction sources usually use pyroelectric components, which lose charge balance when the temperature of the infrared radiation of the human body changes, and release the charge outward. The subsequent circuit can generate an alarm signal after detection and processing.
This probe is aimed at detecting human radiation.
Therefore, the pyroelectric element must be very sensitive to infrared radiation with a wavelength of around 10 μm. In order to be only sensitive to infrared radiation, its radiation surface is usually covered with a special Fresnel filter, so that the interference of the environment is obviously controlled.
There are two types of Fresnel lenses: refractive and reflective.
Its function is to filter and focus, and refract (reflect) the pyroelectric infrared signal on the PIR; the second is to divide the detection area into several bright areas and dark areas, so that the moving objects entering the detection area can change with temperature. The form produces a changing pyroelectric infrared signal on the PIR, so that the PIR can produce a changing electrical signal.
A passive infrared probe whose sensor contains two pyroelectric elements connected in series or parallel to each other.
Moreover, the polarization directions of the two electrodes are just opposite, and the background radiation of the environment has almost the same effect on the two pyroelectric elements, so that the electric discharge effects cancel each other out, so the detector has no signal output. Once a person invades the detection area and moves laterally, the infrared radiation of the human body is focused by part of the mirror and received by the pyroelectric elements. However, the heat received by the two pyroelectric elements is different, and the pyroelectricity is also different, which cannot be canceled. After signal processing And alarm; if it does radial movement, its detection ability will be much weaker.
Infrared PIR VS Airtouch Radar Solution
From the above comparative analysis, infrared can meet very limited functions and conditions of use. At the same time, it has many defects such as ugly appearance, easy to be disturbed by temperature, airflow, and heat source, low sensitivity, and short service life. , small size, high sensitivity, good consistency, stable performance, easy to use, etc. It can provide much more comprehensive target information (distance, speed, orientation) than infrared, and realize functions such as micro-motion and life presence detection, and the intelligent application is more expandable.
The high cost performance 5812 chip of AirTouch Technology
The 5.8G SOC radar chip AT58MP1T1RD (5812) innovatively launched by AirTouch Technology, while maintaining its excellent radar performance, greatly reduces the cost of radar chips, module peripheral circuit costs, production and testing costs, etc.Therefore, in terms of overall cost performance, it can PK PIR pyroelectric infrared. Thanks to the high level of integration of the Airtouch Technology chip, the size is greatly reduced (the minimum can be 14mm*14mm), which can meet the needs of various structural sizes, which greatly promotes the development of intelligent sensing products.
With the rapid development of the Internet of Things, sensors, as the bottom layer and core of the Internet of Things, have also led to an explosion, and more and more industries and products are using sensors to complete intelligent upgrades. Based on the advanced nature of radar technology in IoT sensing, with the continuous optimization and upgrading of civilian radar technology, the advantages of radar sensing technology solutions in function, performance, stability, and anti-jamming characteristics will be more perfectly reflected. As the world's leading IoT sensor expert, backed by a strong team and abundant funds, Airtouch Technology will focus on high-performance RF, microwave/millimeter wave radar sensing technology, low-power MCU technology and SoC technology to help things Intelligent upgrade of networking, smart home, smart lighting, smart security and other industries.
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