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                              How Radar Sensors Significantly Improve the Energy Efficiency of the Smart Home































           Figure 5: Samsung Frame TV 2021 switches from Art Mode to Sleep Mode when no one has been detected for a user-specified time period.


           switches the TV from Art Mode to Sleep   Furthermore, falling prices for consumer   combined with temperature and CO 2  sensors,
           Mode when nobody has been nearby for   electronics are increasing cost pressure on   so the system is activated as needed — for
           a user-specified time. This not only saves   components. Hence, 3D time-of-flight (ToF)   example, when someone is in the room,
           energy but also extends display lifetime.  and camera sensors are often too expensive   when the CO 2  level is too high, or when the
                                               to be implemented for presence detection.   temperature exceeds the predefined limits.
           RADAR SENSORS ARE THE               Even powerful PIR solutions, which not only   Whereas other sensing technologies often
           MOST SUITABLE SENSING OPTION        affect the design of the product housing    provide only binary information such as pres-
           FOR SMART-HOME DEVICES              but also require an additional Fresnel    ence or absence, a radar sensor can also check
           Of all the available motion-detection solutions,   lens, amplifier, controller, etc., increase    the number of people in the room and adjust
           radar sensors have the highest sensitivity even   the bill-of-materials cost. Infineon’s    the level accordingly at an early stage, or even
           for the smallest movements, some of which are   BGT60LTR11AIP radar sensor, by compari-  check the people’s positions and distances to
           even invisible to the human eye. PIR sensors   son, requires only a minimum of supporting   control the direction of the airflow.
           cannot compete in terms of sensitivity. Also,   components, especially in autonomous oper-  There are many other possible use cases
           radar does not rely on body heat as PIR sensors   ation, and therefore has the smallest impact   — for example, sound systems that track the
           do, because it is an active sensing technology.   on system costs. Because of their tiny size,   position of the listener and continuously
           This ensures that a person is detected even   radar sensors can also be incorporated into   optimize volume and sound parameters
           when they are barely moving or not moving at   small and thin electronic devices.  accordingly; TVs with child care, which mea-
           all. But arguably one of the biggest advantages   In addition, radar sensors are robust in   sure the viewer’s distance and give a warning
           is detection through non-conductive materials.   dusty, smoky, or humid environments where   if the child’s eyes are too close to the screen;
           While infrared, ultrasonic, camera, and other   some laser-based ToF sensors or other   or devices for the elderly or people in need
           image-based sensors must not be covered or   image-based sensors might be subject to   of care, such as alarm systems that call for
           require openings in the product housing,    deteriorations in their detection performance.  assistance in the event of a fall. Thus, with
           a radar sensor can be completely hidden                                 little effort, radar sensors can save energy and
           inside a device. As a result, you do not have   ADDITIONAL SMART FUNCTIONALITIES   contribute not only to people’s comfort but
           to make any compromises in the design of   ENABLED BY RADAR SENSORS     to their personal well-being and safety in a
           the product and can avoid additional manu-  Poor handling of devices also leads to    smart environment. ■
           facturing steps and costs for a housing with   unnecessary power consumption. Users are
           corresponding adaptations.          not always aware of this, but they waste   REFERENCES
             Another possibility is camera-based motion   energy unintentionally when they fail to   1    Martani, C., Lee, D., Robinson, P., Britter, R.,
           detection — for example, for cameras, TVs,   switch off their devices or adjust the settings   and Ratti, C. (2012). “ENERNET: Studying the
           laptops, and other devices that already have   when they are going to be temporarily absent.   dynamic relationship between building occu-
           a suitable image sensor. Image systems have   However, with the aid of radar sensors, this   pancy and energy consumption.” Energy and
           very high power consumption, though they   can be regulated automatically so that users   Buildings, 47, 584–591. bit.ly/3utyL73
           may need good ambient light conditions, and   don’t have to think about it but have the   2   Norford, L., Socolow, R., Hsieh, E., and Spadaro,
           there is a need for image processing to detect   assurance that they are not wasting energy.  G. (1994). “Two-to-one discrepancy between
           motion from a video, which further requires   Besides being used as a presence or   measured and predicted performance of a
           a lot of energy. Lack of privacy is often also   absence detector, radar sensors can add other   ‘low-energy’ office building: Insights from a
           cited as a concern, as camera-based systems   functions to smart devices — for example, in   reconciliation based on the DOE-2 model.”
           invade private spaces, so users do not fully   air-conditioning systems. In such applica-  Energy and Buildings, 21(2), 121–131.
           trust them.                         tions, radar sensors are most efficient when   bit.ly/35FRQIB

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