iNF ｛ ⊙﹏⊙ ｝ says to eric Yu xiang的窩🙄 https://www.techbang.com/posts/61465-wi-fi-not-only-provides-wireless-internet-access-but-also-the-ability-to-estimate-the-number-of-people-in-the-next-room-through-signal-reflection