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EPOCH 4PLUS
Hertz (Hz) The derived unit of frequency defined as the frequency
of a periodic phenomenon of which the period is one
second; equal to one cycle per second.
Symbol Hz. 1 Kilohertz (KHz) = 10
3
cycles per second
1 Megahertz (Mhz) = 10
6
cycles per second.
Horizontal A The smaller length (if rectangular) of the actual crystal.
The software will compute the affective length
automatically.
Immersion Testing A test method, useful for testing irregularly shaped
parts, in which the part to be tested is immersed in
water (or other liquid) so that the liquid acts as a
couplant. The search unit is also immersed in the
liquid, but not in contact with the part being tested.
Incidence, Angle of The angle between a sound beam striking an acoustic
interface and the normal (that is, perpendicular) to the
surface at that point. Usually designated by the Greek
symbol α (alpha).
Indication The signal displayed on the screen signifying the
presence of a sound wave reflector in the part being
tested.
Indication (Defect) Level The number of decibels of calibrated gain which must
be set on the instrument to bring the indication (defect)
echo signal to peak at the reference line on the screen.
Initial Pulse (IP) The pulse of electrical energy sent by the pulser to the
transducer.
Leg In angle beam testing, the path the shear wave travels in
a straight line before being reflected by the opposite
surface of the material being tested.
Linearity, Vertical or
Amplitude
The characteristics of an ultrasonic test system
indicating its ability to respond in a proportional
manner to a range of echo amplitudes produced by
specified reflectors.
Linearity, Horizontal or
Distance
The characteristics of an ultrasonic test system
indicating its ability to respond in a proportional
manner to a range of echo signals, produced by
specified reflectors, variable in time, usually a series of
multiple back reflections.
Longitudinal Wave Mode of wave propagation characterized by particle
movement parallel to the direction of wave travel.
Main Bang Term used to describe the Initial Pulse Voltage.
Term Definition
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