Geophysical Survey Systems, Inc.
SIR® 4000
Manual
MN72-433 Rev F
54
Process Menu
1
Gain Mode and Edit Gain Curve:
The thin, red line superimposed over the scan in the O-Scope
window is the gain curve. The centerline of the scan is zero and to the left of it is negative (decreasing
gain) and the right is positive (increasing gain). Gain is applied in dB along an exponential function to
model signal loss. Your goal should be to have a gain curve that creates a scan trace with balanced
amplitude changes from top to bottom.
•
Select Auto Gain Mode:
If Auto Gain Mode is already selected you can press the Init control
button at the bottom of the screen to apply an automatic gain curve to the current scan trace. This
will cause the system to re-initialize and add/subtract gain to produce a visible signal. Drag the
antenna over the area and look for evidence of clipping. If your data becomes clipped, leave the
antenna over the area where it is occurring and re-initialize by pressing the Init control button.
This will decrease the gains so that the data will not clip.
•
If you plan to collect multiple profiles and wish to compare them, it is usually best to set the gain
to Manual Gain Mode, once you find gain settings which are workable (you can see targets and
the signal does not clip).
•
If you are performing real-time locating, then leaving the Gain Mode set to Auto will allow you
to use Init when your signal quality changes between profiles.
•
Edit Gain Curve:
If portions of the signal are under- or over-gained after using Auto Gain Mode,
you can try increasing or decreasing the number of gain points. The number of gain points
selected are evenly distributed along the scan trace and changing the number of points can change
where along the scan trace amplification is increased or decreased.
o
Select Edit Gain Curve.
o
Add or erase points to modify the gain curve.
o
Save and Exit to return to the Collect Setup screen.
Output Menu
1
Scale and Units:
Verify that you are using the appropriate vertical scale, vertical units, and
horizontal units.
2
Colormap, Color Stretch, and Color Slide:
Check that you are using your preferred color scale
settings.
System Menu
1
AutoSave:
How you set this is based upon whether or not you want to save all of the files you
collect or be selective. With AutoSave turned on you’ll automatically save every profile.
•
If performing real-time locating, turning this to On may be beneficial as it will decrease the
number of selections you have to make to clear your screen.
•
If collecting individual profiles to build into a 3D grid using the software it is recommended to
turn AutoSave Off. As you finish collecting one line this pauses data collection while you get in
position to start the next line.
2
Save Setup:
Once you’ve made all of the modifications to the settings listed above it’s a good idea
to save your setup. This way you can recall it later if you have to restart the system or if you know
you’ll use these settings on a regular basis.
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