Basic principle: Readings present the helpful voltage according to the typical value of samples over a complete variety of intervals of the fundamental frequency.) b?n l?u ý l?i nh?p li?u. Trong ?i?u ki?n có th? MinhNgoc luôn hi?n ho?c trong m?t kho?n th?i gian nh?t ??nh tr??c khi ?i?u ch?nh, t?t nh?t b?n nên dùng ph??ng pháp t? ??ng ho?c xâ