Cambium Networks PMP 450, Planning Manual

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PMP 450 Planning Guide
Visual line of sight does not guarantee radio line of sight.
Surveying Sites
Factors to survey at potential sites include
•
what pre-existing wireless equipment exists at the site. (Perform spectrum analysis.)
•
whether available mounting positions exist near the lowest elevation that satisfies line of site, coverage, and
other link criteria.
•
whether you will always have the right to decide who climbs the tower to install and maintain your equipment,
and whether that person or company can climb at any hour of any day.
•
whether you will have collaborative rights and veto power to prevent interference to your equipment from
wireless equipment that is installed at the site in the future.
•
whether a pre-existing grounding system (path to Protective Earth ) exists, and what is required to establish a
path to it.
•
who is permitted to run any indoor lengths of cable.
Clearing the Radio Horizon
Because the surface of the earth is curved, higher module elevations are required for greater link distances. This
effect can be critical to link connectivity in link spans that are greater than 8 miles (12 km).
To use metric units to find the minimum height required to reach the radio horizon use the following equation:
Radio horizon distance (km) = 4.12 (SQRT(h1) + SQRT(h2))
Where: Is:
h1 height of the AP
h2 height of the SM
To use English standard units to find the angle of elevation, use the following formula:
Radio horizon distance (km) = 1.42 (SQRT(h1) + SQRT(h2))
Where: Is:
h1 height of the AP
h2 height of the SM
pmp-0047 (March 2014)
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