GSSI StructureScan Mini XT, Manual

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Geophysical Survey Systems, Inc. StructureScan™ Mini XT
Manual
MN 70-813 Rev E 21
Section 6: Calibrating for Depth in the ScanMax App
The Mini XT, like all GPR instruments, records the elapsed time between transmission and reception of
the RADAR pulse. In order to produce an accurate depth, it is necessary to calculate the velocity of that
pulse as it moves through the concrete. The ScanMax App has three tools available to assist in the
Calibrate menu during data collection. These tools are also available in Playback mode so you can apply
them to already collected data.
To access, position the backup cursor on the center of a hyperbola and select Calibrate from the menu
carousel. You will see the screen below and the following options will be displayed
• Set Depth:
Enter in a known depth to allow the software to calculate the velocity based on a
known depth and time. This is also known as ground truth. It is the most accurate calibration
method because it is based on empirical measurements.
• “Blank”:
Clicking the middle button on the handle keypad will leave this menu and return to the
previous menu.
• Set Dielectric:
Use a hyperbola fitting tool to model the shape of the actual data image. This uses a
process called migration to calculate the dielectric value of the concrete. Different dielectric values
cause different dispersion angles which results in hyperbolas of a particular shape. Since RADAR
wave velocity is a component of the dielectric value, the Mini XT is able to back calculate the
velocity of the energy by calculating the dielectric value resulting from the shape of the chosen
hyperbola.
• Auto Depth:
Choosing Auto Depth will cause the Mini XT to run GSSI’s patented auto-depth
algorithm which takes several signal parameters into account in order to accurately calculate target
depth.
• Save Image:
Saves a screenshot of the current window as a PNG file.