Checkline DFX-7 - Manual (Page 87)

DFX-7 Ultrasonic Flaw Detector
83
The diagram above is an RF view, showing both the positive and negative going
cycles for purposes of explanation. Notice the +/- positions in the diagram. The
positive phase is everything above the horizontal center line, and the negative
everything below the center line. The baseline is found at position (A), and
considered zero dB. If +RECT was selected as the view, only the positive portion of
the waveform would be displayed. Equally, if the gate polarity was set to positive, as
in the diagram at (C), it would also appear on the display. However, if it was set to
negative, would not appear on the display. In the example above, the gate is set to
positive and will detect on the positive going waveform cycles shown in the box (B).
Toggle Polarity (+/-)