c. The general problem for intervisibility is determining how much a line of sight between two

stations will clear or fail to clear an intervening obstruction. Use the following formula to make this

determination:

=

The elevation of the line at obstruction (in meters)

=

The elevation of the lower station (in meters)

=

The elevation of the higher station (in meters)

=

The distance from the lower station to the obstruction (in kilometers)

=

The distance from the higher station to the obstruction (in kilometers)

The first two terms of the above formula are a solution of similar triangles. The last term is the

curvature and refraction correction. If the two stations are at the same elevation, the obstruction can be

cleared using signals of equal height, and the above formula becomes the following simple formula:

The height of the signal at each end becomes the following formula:

d. For a given length (K) between stations, the elevation required at one station to see the other

station across a level surface (such as water) is K2 X 0.0676. If both stations are raised to the same

elevation, the height (h2,1) required at each