User's Manual

Smart Systems User’s Manual Version 1.1
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In Noggin
plus
mode, hyperbola Matching calibration can be done during data acquisition
and also while viewing previously collected data.
If units are metres then depths will appear in metres and velocities in metres per
nanosecond (m/ns). If units are feet then depths will appear in feet and velocities in feet
per nanosecond (ft/ns). To change units see Section 6.3.1 – Depth Units.
Target of Known Depth
If there are no suitable hyperbolas visible in the data to perform the Hyperbola Matching
described above, it may be the situation that there is a target of known depth in the area
being scanned. If this is the case, selecting the button with the circle with a horizontal
line through it will superimpose a horizontal line on the data. This line can then be
moved up or down until it lies on top of the Noggin response to the known target. Then,
the user can adjust the velocity value up or down until the known target depth is correct.
Once the depth is matched, the current velocity value is the one used for all subsequent
data acquisition.
(a) (b)
Figure 6-4: Using a target of known depth to extract velocity. After selecting CALIB, choosing the
known depth button (a circle with a horizontal line through it) will superimpose a horizontal line on
the data (a). Using the depth buttons, this line can then be moved up or down until it lies on top of
the Noggin response to the known target (b). Then, the user can use the velocity buttons to
adjust the velocity value up or down until the known target depth is correct. Once the depth is
matched, the velocity value should be used for all subsequent data acquisition.