GSSI SIR 30, Manual

Page: 52 / 150

Geophysical Survey Systems, Inc. SIR® 30
Manual
MN 93-101 Rev E 46
Figure 67: Systems Settings\Antenna.
STACKING (FIR):
This is a horizontal or spatial filter. The value is expressed in scans. This will smooth
the data and reduce random trace-to-trace noise. This value should be set very low. Common values are
3-7 scans.
BACKGROUND REMOVAL FIR:
This is a horizontal or spatial filter. The value is expressed in scans. The
background removal filter is a horizontal Low Pass filter that works by subtracting a running average
number of scans from the data and outputting the results. This filter has the effect of removing flat lying
features that are longer than the specified filter window. This would include the direct coupling pulse and
any other signal in the data that is time constant. This filter is very useful for removing flat, horizontal
noise bands in the data. This filter value should be set very high. GSSI recommends that a value of 1023
scans be used when running a FIR background removal.
Note:
The User should use care when applying a Background Removal filter. While the Background
Removal filter is useful for removing ringing noise bands from the data it can also removal real horizontal
or sub-horizontal features e.g. layer reflections.
SIGNAL PROCESS > ADVANCED FILTERS
These are a class of specialized filters used during data collection. The User may still apply an FIR or IIR
filters as desired.
SIGNAL FLOOR:
This filter will analyze the data’s signal to noise ratio and place a solid green line at the
time\depth where the signal to noise ratio becomes marginal. This is to assist the User in recognizing the
maximum range of usable data. This filter is saved in the DZW file and can be reviewed in RADAN 7.
MIGRATION:
This function will perform a hyperbolic summation of the data file during data collection.
This may improve the visibility of point-like targets such as utilities or rebar. You will need to specify a
Dielectric Constant value in RADAR Configuration Scan sub menu. A correct value will collapse the
hyperbolas into points. Migration works best on homogenous materials such as concrete
ADAPTIVE BKGREM:
This function should be used concurrently with the MIGRATION function to
remove the background from data that has numerous high amplitude targets e.g. rebar in concrete.
POSITION TRACKING:
This filter is designed to correct the data signal position for any temperature
related drift. With Position Tracking enabled, the surface position is corrected in real time. Each scan
(trace) is shifted up or down to keep surface position at fixed sample number.