User Manual

Exalt Communications, Inc.
Exalt i-Series Installation and Management Guide
5000001 95
2007-06-25
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.
If the link was designed with poor link margin, there are likely many cases of bit errors
and outages. The antenna system and transmission line can be upgraded to help reduce
this. If the link design was installed with sufficient margin, but RSL is reduced, the
remaining link margin may no longer be enough to maintain a reliable link. The causes of
RSL reduction were previously described, but are usually due to new path obstruction(s)
or antenna misalignment due to wind or mechanical factors. The antenna height or
location can be changed to overcome new obstructions. Realignment of the antenna,
and/or improvement to mechanical structures can help overcome antenna misalignment.
Moisture in the Transmission System
If the connectors on cables and antennas and egress junctions are not properly
weatherproofed, moisture can get into the transmission system and cause significant error
conditions and erratic performance. In many cases, the transmission system must be
replaced. A VSWR meter is one means to identify such issues. Physical inspection can be
helpful, and if changes to the weatherproofing occur (such as cracks), the
weatherproofing must be replaced before it leaks.