High and low points between the two sites are as follows:
6-kilometer distance
150 meters
10-kilometer distance
132 meters
16-kilometer distance
144 meters
22-kilometer distance
120 meters
24-kilometer distance
150 meters
32-kilometer distance
156 meters
(2) You use the following steps to determine LOS:
(a) Step 1 - Determine the scales used from the contour map. In this exercise, this
is given in meters/kilometers.
(b) Step 2 - Identify the locations of the two points on the map. Draw a straight
line on the contour map between the two points. Measure the distance between the two points.
In this exercise, this is given to you (the distance from point A to point B is 40 kilometers).
(c) Step 3 - Determine the elevation at each site by analyzing the contour lines on
the map. This information is provided in this exercise.
(d) Step 4 - Mark the location of each site on the nonlinear graph paper. In this
exercise, the elevation at point A is given as 130 meters. The antenna height is given as 50
meters. To determine the total elevation at point A, add the elevation of site A and the elevation
height (130 plus 50 equals a total elevation of 180 meters). As indicated by the Step 4
instructions, mark the location of point A 180 meters above the 0-kilometer/0-mile elevation
scale on nonlinear graph paper (see Figure 2-5). Next, mark the location of point B on the
nonlinear graph paper. In this exercise, the elevation of point B is 136 meters. Since point B is
40 meters from point A, go to the 40-kilometer mark on the distance scale and then move up
vertically until the 186-meter elevation is reached. The location of point B is then marked (see
Figure 2-5).
(e) Step 5 - Draw a straight line between points A and B.
(f) Step 6 - Plot a profile of the terrain between the two sites. This step is
normally done by analyzing the contour lines between the two sites and determining the
significant high and low points intersected by the line. In this exercise, the information is
provided (plotted on the nonlinear graph paper in Figure 2-5). As previously stated, LOS exists
between the points A and B in this exercise.
(3) Figure 2-6, page 2-10, illustrates a non-LOS profile. An obstruction is present at
the 24-kilometer distance mark.
2-9
SS0121
Previous Page
