Geophysical Survey Systems, Inc.
SIR® 4000
Manual
MN72-433 Rev F
48
2
Select your saved setup from the list using either the Control knob or arrow keys. Once the desired
setup is highlighted press either the Control knob or Enter button.
Radar Menu
1
Collect Mode:
Set to Distance.
•
Dielectric/Soil Type:
Choose a Dielectric Constant or Soil Type that best represents the area
you are surveying (See Appendix D: Dielectric Values for Common Materials)
2
Depth/Time Range:
There are two options for setting the depth or time range.
•
Full Range:
With the system in Collect Setup mode and data scrolling across the screen, move
the antenna. As you do so, observe the scan trace displayed in the O-Scope window. When the
scan trace gets to a depth/time where there is more noise/interference than signal strength, you’ll
see the scan trace jump from negative to positive and appear craggy. To setup the system so that
you’re collecting the maximum range of data possible you’ll want to see some of that noise in the
scan trace. If no noise is apparent then you should increase your depth or time range until about
25% of the scan trace consists of noise. The noise to signal ratio will change as you move across
your survey area. Keeping some noise on the screen will help ensure that you always collect the
full range of quality signal.
•
Target Specific:
With the system in Collect Setup Mode and data scrolling across the screen,
move the antenna and find a target that you want to image. Note its position on the screen and at
what time/depth it occurs. Ideally, it should be halfway down the screen so that you can image
targets above and below it. If it is not properly located, change the depth or time range.
3
Scans/Unit:
Generally you need a minimum of 10 scans to draw a recognizable hyperbola. The rule
of thumb is to have 10 scans divided by the depth of the shallowest object. If you want to image a
target 10 feet deep, 10 scans / 10 feet = 1 scan/foot. For 5 feet deep, 10 scans / 5 feet = 2 scans/foot.
•
For locating structural features in concrete with the 1.5/1.6 GHz antenna, we usually recommend
90 scans/ft. For utility and tank location, we usually recommend 6-24 scans/ft. While this is more
than the minimum rule of thumb, GSSI has found these densities work well in the widest variety
of situations.
Process Menu
1
Gain Mode and Edit Gain Curve:
In the O-Scope window the gain curve is the thin red line
superimposed over the scan. The centerline of the scan is zero, to the left of it is negative (decreasing
gain) and to the right is positive (increasing gain). To model signal loss, gain is applied in decibels
(dB) along an exponential function. 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, press the Init control button at
the bottom of the screen to apply an automatic gain curve to the current scan trace. This will re-
initialize the system and add/subtract gain to produce a visible signal. Move the antenna and look
Note:
If you recall a setup after configuring the GPS, the SIR 4000 will recall a baud rate of 4800.
If this does not match your previously selected Baud Rate, return to the Introduction Screen and
reset your Baud Rate in the GPS Configuration window.
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