Basic principle: Readings show the effective voltage determined by the common worth of samples over a complete amount of durations of the basic frequencyK?t qu? x? s? toàn qu?c t? ??ng c?p nh?t liên t?c t?ng gi?i nh? ng?i xem tr??c h?i tr??ng x? s? trong su?t quá trình m? th??ng t? h? th?ng máy ch? k?t n?i d? li?u tr?c tuy?n c?a ??i Lý Vé S?