conversion chart (figure 2-9), convert the heights of all prominent
points (solid line curve in figure 2-10) to corrected curve (dashed
line of figure 2-10).
Figure 2-10.
Plotting profiles on linear graph paper
Often profile charts indicate an LOS path before the corrections.
With corrections, however, obstructions become apparent. Check your
corrected graph to ensure a true LOS path exists.
If obstructed,
discard the site and select a new one.
If intervening obstructions
exist on the path (as in path C of figure 2-8), or if the lowest
point of the line drops below the curvature of the Earth (as in path
B of figure 2-7), poor communications result.
Selecting paths such
as the one indicated as path D of figure 2-8 provides effective
communications links.
NOTE: A quicker method of determining an LOS path may be used. After
drawing the straight line on the graph, determine the lowest
point on the line. Scan the corresponding line on the contour
map to determine if any point is higher than the lowest point
of the profile chart line. If not (as in path D), an LOS path
exists, and you need not plot the profile of the intervening
terrain. If there are points above the lowest elevation (as in
path C), you must then draw a complete profile to define
obstructions.
2-16
SS0016
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