YUSHI YUT-2620 Manual page 48

YUSHI INSTRUMENTS
SCR (signal to clutter ratio): the ratio between the ultrasonic signal amplitude and the biggest
background noise, generally represented by decibel (dB).
Gain: the gaining logarithmic form of the amplifier voltage received by the ultrasonic defectometer,
represented by decibel (dB).
DAC: a group of curved lines drawn on the basis of the distance of the known reflector which has
produced echoes, the gaining of the instrument and the sizes of the reflector according with the regulated
principles. In practice, the equivalent size can be estimated through the curved lines based on the
detected flaw distance and gain value.
Coupling: the function of conveying sound waves between the probe and the tested workpiece.
Test block: the sample used for evaluating the property and flaw detecting sensitivity of the ultrasonic
system.
Standard test block: the blocks whose materials, shapes and sizes having been appraised by the
authoritative organizations or supervising departments used for testing the ultrasonic testing system or
the system performance and adjusting its sensitivity.
Reference block: The blocks made from the similar materials of the tested ones for adjusting the
ultrasonic testing system sensitivity or comparing the flaw sizes.
Probe: the device for transforming the electricity and sound which can either emit or receive (or both
emit and receive) the ultrasonic energy. It usually consists of trademark, plug, case, back lining,
piezoelectric element, protective film or shim block.
Straight probe: the probe used for detecting flaws in a vertical direction, mainly for longitudinal wave
flaw detection.
Angle probe: used for angle flaw detection, mainly for transverse wave flaw detection
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