Map GPS Coordinates - GPS Map Coordinates ... - Global Mapper

Global Mapper User's Manual
The From Sight Elevation section allows the user to select the height at the start position (left side of graph) to
use in the line of sight calculations. This height can be specified in either feet or meters above the ground or
above sea level. The To Sight Elevation section provides the same functionality for the end position (right side
of graph).
The Fresnel Zone Specification section allows you to have the line of sight analysis also check that a certain
portion (the Percent Clear value) of the first Fresnel zone for a transmission of a particular frequency is clear.
The typical standard is that good visibility requires that at least 60% (the default) of the first Fresnel zone for
the specified frequency be clear of obstructions. If Fresnel zone clearance is being selected the specified
percentage of the first Fresnel zone will be drawn on the line of sight analysis dialog as a dotted line
underneath the straight sight line.
The Earth Curvature section allows the user to specify whether they want to take the curvature of the earth
into account while performing the line of sight calculation. In addition, when earth curvature is being used,
they can specify an atmospheric correction value to be used. The atmospheric correction value is useful when
determining the line of sight for transmitting waves whose path is affected by the atmosphere. For example,
when modeling microwave transmissions a value of 1.333 is typically used to emulate how microwaves are
refracted by the atmosphere.
Selecting the Exclude Endpoints when Finding Minimum Clearance options causes the first and last 5% of the
elevations along the profile to be ignored when finding the minimum clearance point.
After setting up the line of sight calculation in the dialog and pressing the OK button, the line of sight will be
displayed in the path profile window (pictured below). Along with the line depicted the actual line of sight,
the position and vertical separation of the minimum clearance of the line of sight will be displayed with a
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