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8. Working in TOP View (Optional Feature)
NOTE: The TOP View quadrature encoder controls the
collection of TOP View data in two ways. First, data
is only collected while the encoder wheel is turning
(i.e.: while the probe is moving over the test piece).
Second, the encoder allows data to be overwritten
when its direction of travel is reversed. For instance,
moving the probe and encoder forward over a distance
of 10 cm, then reversing the probe's movement by 2
cm, will cause the last 2 cm of forward-moving data
to be replaced by the 2 cm of reverse-moving TOP
View data.
Accessing the TOP View Control Menu
When TOP View mode is initiated, the Knob Emulator /
TOP View Control Menu is displayed. While this menu is
displayed, the knobs are disabled. In TIMED mode, pa-
rameters can be adjusted by pressing
or KNOB-. Pressing any other non-menu key (such as
) enables the knobs and "hides" the TOP View Control
Menu. While acquiring data in ENCODED mode, only the
key below STOP is enabled.
While operating in TOP View mode, pressing
the display's menu bar from any currently active menu
to the Knob Emulator / TOP View Control Menu. This
menu, shown in
Figure
8-5, allows the screen to be frozen
by pressing
below STOP, or (in TIMED mode only)
cleared by pressing
display to be cleared and restarted or to resume data
collection from the point at which it was stopped. See
Section 8.3
to work with a frozen TOP View Display or
Section 8.4
to store the acquired TOP View data in a
data set.
Selecting the TOP View DATA SOURCE
At any time when operating in TIMED mode (or when the
display is frozen in ENCODED mode), the displayed TOP
View data can be modified using the DATA SOURCE
Function (accessed via the VIEW Submenu in the DIS-
PLAY Menu). Note that options include:
AMP A – Amplitude of A-Scan echo triggering A-Gate
AMP B – Amplitude of A-Scan echo triggering B-Gate
TOF A – Sound path distance to A-Gate triggering echo
TOF B – Sound path distance to B-Gate triggering echo
Refer to
Figure 8-5
to see the icons used to indicate
whether TOP View is operating in amplitude or TOF
mode. These four data sources are also the only data
related to the TOP View display that can be accessed
from a frozen display
(Section
set
(Section
8.4).
Page 102
below KNOB+
switches
below CLEAR. It also allows the
8.3) or stored in a data
Adding or Removing the A-Scan from the TOP
View Display
While acquiring TOP View data, the A-Scan representing
a selected beam can be displayed on the screen, along
with the TOP View image. Note that if acquiring data in
ENCODED mode, this function must first be set in TIMED
mode before activating ENCODED mode. Press
select the desired display view from:
•
A-Scan and TOP View
•
TOP View only
Setting the ASCAN MODE to PEAK in TOP View
When operating in TOP View, the ASCAN MODE Function
(in the VIEW Submenu) can be set to PEAK. Note that
if acquiring data in ENCODED mode, this function must
first be set in TIMED mode before activating ENCODED
mode. When selected, PEAK mode transforms the A-Scan
display into a series of segments, each representing one
beam or cycle in the phased array setup
maximum value achieved by each beam or cycle over the
entire TOP View display determines the distance from the
baseline at which its segment is drawn. Note that ASCAN
MODE's NORMAL setting, which is available whether or
not TOP View is enabled, is described in
Using the IF GATE in TOP View Mode
The interface (IF) GATE's primary function is to compen-
sate for varying probe-to-test-piece distance by adjusting
the A- and B-GATE starting points.
Variations of this distance occur either because of miss-
orientation of the part relative to the probe or because
the surface of the part is irregular. These variations are
possible when a water gap is employed for coupling or
when soft material is used.
NOTE: While highly infrequent, extreme temperature
variation will change this probe-to-test-piece dis-
tance by altering ultrasonic velocity through the delay
material.
Phased-array probes typically produce multiple beams,
each of which can produce a slightly different reflector
distance. Therefore, an IF-, A-, and B-Gate triggering
occurs for each beam. GATE positions for each beam
determine the test-piece area evaluated for transfer to
the TOP View display. If improperly oriented probes or
surface irregularities were not accounted for by adjusting
the A- and B-Gate starting points, the material depth of
interest may not be evaluated.
to
(Figure
8-5). The
Section 3.3.
PHASOR XS Operating Manual
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