User's Manual

605-0000-595 Subscriber Terminal Installation and Commissioning
40
Preparation
Site Selection
Site Readiness
Verifying that the site is ready for the installation of the ST equipment.
Check access to the building before unloading or unpacking the equipment.
Outdoor Unit Important Installation Considerations
Geographical deployment within guidelines: Just because a ST seems to get a link on an
excessively long distance or on a side lobe to a sectored antenna, this doesn’t mean it will
work reliably. Frequency (Radio) planning is essential for the area covered (including
frequency sweep to identify possible interferers).
Clear line of sight: This is the single most likely reason for an installation not to work. Check
for:
• Any buildings or large trees, especially ones close to the ST, which obscure
the line of sight will significantly reduce the RF power, and could cause
problems with reflections. Trees should be at least 50m from ST installation
RF path. Although AS4020 can operate through trees,absorption losses for a
single tree can increase the path loss 6-9dB and foliage movement due to
wind can cause varying path losses degrading BER performance. Note:
Trees exceeding a distance of 50 metres from the antenna are considered
ineffective to the units' performance.
• Place the outdoor unit as high as possible to avoid local clutter caused by
people/vehicles/trees. Make sure the outdoor unit is actually pointed at the
CT. Mounting height should normally be 5-7 metres above ground level.
• Ensure that the antenna path has sufficient near field clearance (see 'Site
Selection' below)
• No other radio broadcasting units are likely to transmit across or into the
antenna boresight and have a separation from Airspan equipment of at least
2m.
• For efficient and reliable service it is suggested that the external mounting
location of the outdoor unit be chosen such that once 'panned' for optimum
signal level it observes the following criteria:-
• Avoid obstructions such as adjacent walls or overhanging roof eaves,
within 15° in the horizontal plane and 30° in the vertical plane (see
figure below).
• Ensure adequate clearance is allowed for 'panning' the outdoor unit.
• The antenna is capable of being 'panned' with at least 15° of
adjustment either side of the direction of the CT antenna.
These guidelines should not be violated during the outdoor unit panning
process.
Physical separation: STs at the same location must have at least 1 metre separation
between their outdoor units, to stop coupling between them causing interference.
Correct orientation: The ST outdoor unit has a required orientation, mounting it at 90 degrees
to this (e.g. by attaching it to a horizontal rather than vertical mounting bar) will affect the RF
performance.