User's Manual

Exalt Installation and Management Guide
EX-i Series GigE (FDD) Digital Microwave Radios
102 202675-008
2016-06-01
sources of interference, measure these sources, and determine potential remedies to take to operate in
the presence of interference.
If a spectrum analyzer is not available, the radio’s RSL port can help determine RSL levels of
interfering signals. By turning the far-end radio off, the residual RSL measured by the radio indicates
the level of interference seen by the radio. It is possible that interference levels below that which can
be measured still have an impact on the radio system – especially if the radio system has low fade
margin or is using a high order modulation.
Repositioning the antenna and/or changing polarization, or upgrading the antenna to a higher gain,
and/or using a high-performance antenna, are all secondary means that can be used. It may be
necessary to perform combinations of both radio changes (retuning, occupied bandwidth reduction)
and antenna system changes (position, polarization, upgrade). Local regulations may not permit
antenna system changes without re-licensing or other notification.
Path Obstruction
A path obstruction is defined as an object, such as a building or tree, impeding the proper path of the
radio system. If the system design was proper at the time of installation and issues arise at a later date,
an updated path profile and survey may be necessary to identify changes in path clearance.
Misaligned Antenna
At the time of initial installation, it is critical that the antennas at each end are properly aligned and that
the designed RSL is achieved. However, antennas may become misaligned due to high winds, changes
in the guy-wiring systems keeping the antenna mast stable, or loosening of the antenna mounting
hardware. A reduction in the RSL of the link is symptomatic of this condition, but this condition is not
the only condition that results in a reduction of RSL. However, if conditions occur where the antenna
alignment may be suspected, the mechanics must be inspected and the antennas realigned.
Faulty Antenna
A faulty antenna is rare, but is still a possibility. In some cases, the mechanics of the antenna feed can
get moisture inside, or a bad or weak connection in the pin and connector structure of the antenna may
occur. A VSWR measurement of the antenna connection can be made to verify this condition.
Improper Grounding
In addition to being a potential human safety issue, improper system grounding is a somewhat
common condition that can cause continuous bit errors or bit errors when metal objects come in
contact with the radio, transmission system, or racking system. If touching the radio causes errors,
grounding is the cause. It can be difficult to identify grounding problems, but a professional electrician
can normally inspect a system and identify if there are deficiencies in the grounding system.
Insufficient Link Margin
Ideally, the link was designed with enough link margin (fade margin) to allow for multipath
propagation and atmospheric fading and still remain reliable. In some cases, link margin is
compromised by economic factors, such as using low-cost RF cabling or lower-cost antennas that have
less gain or deficient performance compared to higher cost transmission system components. In some
cases, there may be antenna size restrictions that forced the design to not have the desired amount of
link margin.