User Manual

User Reference and Installation Manual 3-6
MDS 5800 II
3.5.2 Site Evaluation Process
The following steps must be completed to perform a successful site evaluation. Each step in the
process is detailed in the following subparagraphs:
• Ensure RF Safety compliance: Ensure that appropriate warning signs are properly placed
and posted at the equipment site or access entry. For a complete list of warnings, refer
the Safety Precautions listed at the beginning of this manual.
• Ensure Compliance with Laws, Regulations, Codes, and Agreements: Ensure that any
installation performed as a result of the site evaluation is in full compliance with applicable
federal and local laws, regulations, electrical codes, building codes, and fire codes.
• Establish Radio Line of Sight between MDS 5800 II Radios: The most critical step in
conducting a site evaluation is confirming a clear visual and radio Line of Sight
(LOS) between a near MDS 5800 II Radio and a far MDS 5800 II Radio. If LOS does
not exist, another location must be used.
MDS 5800 II Radios in a link must have a clear view of each other, or visual “line of sight”.
Binoculars may be used evaluate the path from the desired location of the near MDS
5800 II Radio to the desired location of the far MDS 5800 II Radio.
To confirm Line of Sight:
- Ensure that no obstructions are close to the transmitting/receiving path. Take into
consideration trees, bridges, construction of new buildings, unexpected aerial traffic,
window washing units, etc.
- Ensure that each MDS 5800 II can be mounted in the position required to correctly
align the MDS 5800 II with its link partner.
MDS 5800 II Radios must also have a clear radio line of sight. If a hard object, such as a
mountain ridge or building, is too close to the signal path, it can damage the radio signal
or reduce its strength. This happens even though the obstacle does not obscure the
direct, visual line of sight. The Fresnel zone for a radio beam is an elliptical area
immediately surrounding the visual path. It varies in thickness depending on the length of
the signal path and the frequency of the signal. The necessary clearance for the Fresnel
zone can be calculated, and it must be taken into account when designing a wireless
links.
As shown in the picture above, when a hard object protrudes into the signal path within
the Fresnel zone, knife-edge diffraction can deflect part of the signal and cause it to reach
the receiving antenna slightly later than the direct signal. Since these deflected signals
are out of phase with the direct signal, they can reduce its power or cancel it out
altogether. If trees or other 'soft' objects protrude into the Fresnel zone, they can