aving a GPS connected to an LMX200™ or Noggin® GPR system automatically generates simple, standard output files that clearly communicate the position of underground features – without the need of any GPR processing software.
During data acquisition, the GPS records the survey paths of all GPR lines and grids collected in a GPR project. When the GPR operator finds a target of interest in the data, they can add a field interpretation by simply touching the target response directly on the display screen to add a colored dot at that position.
The operator can also add a marker flag to indicate objects on the surface that should be noted to assist with data interpretation – things like a change in surface materials, a large metal object nearby that might cause an air wave or a large rut where the GPR antennas were not coupled with the surface.
All this data, the GPS survey paths, field interpretations and marker flags are displayed in the Map View window on the display unit to show the relative position of these observations. This allows the user to quickly see patterns in the data to help with interpretation; for example, if the field interpretations form a straight line, the object is linear.
Figure A shows the Map View screen where the 6 field interpretations are actually two utilities.
When the field work is complete, data is transferred to a USB memory stick by simply connecting it to the display unit. Along with the raw GPR data saved in a GPZ file, there are two other files that are automatically copied to the memory stick:
- A map view of the data in each project is saved in a KMZ format so it can be opened in free GIS software like Google Earth™ (Figure B).
- Spreadsheet (CSV) files listing the latitude, longitude, UTM Northing and Easting and depth of the field interpretations and flags are also output (Figure C). These files can be opened in Microsoft Excel, CAD or other design software.
When an LMX200™ or Noggin® system has a GPS, these file outputs are automatically generated. These files assist the GPR operator in understanding what was found and can be elegant, simple and fast deliverables to clients.
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