Discussing with experts in the radar field about 24GHz millimeter-wave radar. A presence sensor determines the presence or absence of individuals by detecting motion energy values against presence energy values. The working principle of radar involves emitting signals and performing algorithmic analysis based on the reflected signals to ascertain whether a person or object is present. While the principle seems straightforward, achieving high precision is highly challenging due to the significant impact of environmental factors. For instance, the passage of a small mouse, curtains swaying due to an open window, the oscillation of a fan, and vibrations from air conditioning vents can all interfere with the sensor’s energy values. Effectively mitigating these interferences is a major technical challenge. Due to its high precision and practicality, the presence sensor is set to become a key product in home automation. By appropriately setting parameters, it can accurately realize the scenarios of ‘presence’ and ‘absence’.