Sensors & Software Noggin 100, User Manual

Page: 123 / 162

Noggin 13-Survey & Map Mode
109
XY Lines
Set up a first-quadrant XY grid. X data lines run in the X direction, distance increasing from the Y
axis baseline. Line numbers increase in the positive Y direction (see
Figure 13-12 ). Lines must
be equally spaced. Y data lines run in the Y direction, distance increasing from the X axis
baseline. Line numbers increase in the positive X direction. Lines should be equally spaced. The
line spacing of the X lines and Y lines can be different.
It is not critical that all the lines are the same lengths. However, it does make processing easier
if all the lines start at the same baseline position (usually defined as zero (0.0)).
Figure: 13-12 Proper XY grid surveying pattern. Following this pattern and starting each line from the same baseline
minimizes the data editing required to produce a spatially accurate map of GPR data.
13.3.4.2 Grid Dimensions
For grid data acquisition, the grid size needs to be specified. The user needs to input the length
of the X dimension and the length of the Y dimension. The dimensions entered are assumed to
be in the same units as the Position Units (
13.3.1.7: p.97 ), i.e. meters or feet.
On this screen the user needs to highlight the dimension to be changed. The user can toggle
between the X and Y fields by pressing the X/Y button.
The dimension value is incremented or decremented by pressing the +Line or –Line buttons.
The dimension value will change by a value equal to the current Line Spacing in that dimension.
For example, if the Line Spacing in the X direction is 0.5 meters, the grid dimension in the X
direction will increment or decrement in 0.5 meter intervals.
Note that the maximum number of lines that can be collected in each direction is 100.
Therefore, the X and Y grid dimensions cannot be set to a value that will result in more
than 100 lines being collected.
For example, if the Line Spacing between Y lines (defined as lines parallel to the Y axis) is set to
0.25 meters, the maximum X dimension is (100-1) X 0.25 = 24.75 meters. (One is subtracted
because the first line is at position 0.0 meters.)
To increase the X dimension value, the Y line spacing must be increased. Using the example
above, if the Y Line Spacing is increased to 0.30 meters then the maximum X dimension is (100-
1) X 0.30 = 29.70 meters.