Signification and Use of A-scan Images
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QuintSonic 7
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7.2.3
Echo signal with echo lines
Example of an echo signal A-scan image
The above A-scan image represents the complete evaluation procedure. The graphical part of the
image includes three elements:
The time characteristic of the echo signal as calculated by the processing algorithm. It is
represented as a continuous curve running from the left to the right. The signal comprises a
number of positive and/or negative pluses such as the coupling echo pulse and the echo
pulses of the echoes detected at the layer interfaces. According to measuring object, also
portions of interference may be included such as interference pulses or noise interference.
Such interferences can be suppressed by suitable filtering or selections methods described in
section 8. In the above example, interference is very low.
Various horizontal and vertical limiting lines as well as colour-shaded or hatched zones
representing the filtering or selection measures for noise suppression as set by the user. The
example above shows two horizontal broken lines indicating the global clipping limits. See also
section 8.3.3.1. Other filtering or selection measures have not been taken and therefore they
are not shown in the above example.
Extracted echoes resulting from the echo signal setting. These echoes are represented as
vertical lines. They take their start at the zero line and are marked with icons. Each echo has
been extracted from an echo signal pulse and is therefore located within this pulse. Most times,
the exact position and height is identical with the maximum pulse (see also 8.4 Least squares
optimisation).
Not all pulses that can be seen in the echo signal are actually fitted with an echo line. This is due to
the clipping processes as selected and set by the user in order to cut out certain portions of the
Coupling echo
lines (Y, Z)
Layer echo
lines
Clipping-
limits
Time
characteristic of
echo signal with
echo pulses