Figure 9 shows the characteristic of sensing distance versus sensing result at the front
side. The detection distance was measured by following the standing and movement of
student in a testing environment as shown in Figure 8. The output voltage is DOUT that
supplies the power of LED during alarm state of the MCU. Noted that the proposed
sensing module can be detected with a distance of 7.5 m for human body in standing and
moving action. The detection ratio for this distance is 100%.