You could Examine a waveform of one section which has a waveform of another period or Examine which has a previously measured waveform on a similar check point. Website page 69: Conversation K?t Qu? X? S? K?t Qu? X? S? Mi?n Nam K?t Qu? X? S? Mi?n Trung K?t Qu? X? S? Mi?n B?c KQXS Các T?nh