Geophysical Survey Systems, Inc.
SIR® 4000
Manual
MN72-433 Rev F
25
features, such as layers. As the number of stacked scans (n) increases, the influence of new scans
decreases.
The IIR Stacking filter input is in number of scans. Pressing IIR Stacking with either the Control Knob or
Enter button will allow you to select a number of scans.
•
High frequency noise generally has a ‘snowy’ appearance.
•
The larger the number you put in here, the smoother the data will be. It is possible to over-smooth
and ‘smudge’ out real data.
•
A larger number also means that the system is performing a great deal of extra calculations and
data collection speed may be reduced.
•
The Stacking filter maximum value is 1023 scans.
IIR BG Removal
Background Removal is a filter which removes horizontal bands of noise similar to those seen in the
image below. Sometimes these bands are caused by ‘real’ horizontal reflectors, but they can also be
caused by low frequency noise such as antenna ringing. These layers can obscure other ‘real’ horizontal
or point source reflectors.
Filter length should be set to the number
of scans equal to the feature length to be
removed. Any continuous feature within
the data, such as a water table reflector
or a stratigraphic boundary between two
soil types, may also be filtered out by
performing Background Removal. Be
careful to not filter out desired
reflectors.
The IIR Background Removal filter
input is in number of scans. Pressing IIR
BG Removal with either the Control
Knob or Enter button will allow you to
select a number of scans.
•
Determine the length in scans of the feature or noise that you want to remove from the data and
input that number in to the SIR 4000. Features, or horizontal reflections, of this size or larger will
be removed.
•
The Background Removal filter maximum value is 1023 scans.
•
It is recommended that this filter be set last. When Background Removal is turned on the
previewed linescan data and individual scan will gradually be averaged out by the filter and only
noise will be visible. This makes it impossible to preview the effects of other filters.
Horizontal Noise to be
Removed
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