Table of Contents
Advertisement
Site Survey
Terrain Analysis
210
A site survey provides the studies and analysis needed to assure success in a wireless
internetwork design. A site survey is particularly important for long distance and multi-
point connections, and it is essential if there is any doubt whether a wireless internet-
work is feasible or practical for the application.
Site surveys may include few or many studies, depending on the difficulty of the instal-
lation and the questions to be answered. Two survey study options include terrain
analysis and spectrum analysis (see spectrum analyzer). The site survey may include
any or all of the following information:
• The types of antennas and other components best suited to achieve the dis-
tance and multipoint spanning requirements
• How high the antennas must be to avoid obstructions and out-of-phase
deflections
• Potential sources of interference in the alternative RF bands
• The best configuration (base/sub station or point-to-point)
• The best location for each component
• The federal, state, and local requirements that apply for mast construction and
electrical grounding in your area.
Terrain analysis charts the terrain between antennas in order to calculate the best loca-
tion and height for the antennas. This calculation must consider several factors. For
example:
• The height of the lower half of the first Fresnel zone between the antennas rel-
ative to the highest obstructions
• The distances spanned, the number of sites linked, and the types of antennas
needed to reach all the sites
• The margins required to achieve your reliability objectives
The following chart shows 100% of the lower half of the first Fresnel zone for a link
spanning nearly 13 miles with recommended antenna heights of 240 and 70 feet.
Although a mountain is shown blocking part of the F1 signal path between the anten-
Advertisement
Table of Contents
