Triple-Play Service Deployment

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Chapter 4: Troubleshooting the Copper Plant for IP Services
frequency bands should be selectable in order to support
measurement of noise energy within the frequency range of the
circuit/service being deployed.
In summary, the following installation and troubleshooting
procedures should be considered when exploring best practices
for wideband test approaches:
– Wideband Noise – Ideally should be measured during prequalification,
installation, and as a first step in troubleshooting of
potential noise sources. The correct filter for the xDSL service
in use should be applied (including the new J filter previously
defined). This measurement should be used as the first step to
determine the presence of excessive wideband noise. If a noise
problem exists, then further troubleshooting is warranted.
– Impulse Noise – An impulse noise problem may or may not be
readily apparent from the results of the wideband noise test
due primarily to the intermittent nature of impulse noise. A
short-duration impulse noise test should be run during
prequalification and, if possible, installation testing. If an
impulse noise problem is suspected, longer duration testing
may be necessary.
– Spectral Analysis – Spectral analysis capability is an essential
troubleshooting tool that should be used for further analysis of
noise problems including identification of the interference source.
– Next Steps for Noise Problems – In some cases, identification
of the interference source causing excessive noise provides the
path to resolution. For example, a situation in which another
digital service in the same cable binder is not spectrally
compatible and can be moved or addressed directly. In many
cases, however, external noise sources such as AM radio
stations cannot be directly controlled. Under these circumstances,
investigation of the root cause is necessary. Pair
imbalance and bonding and grounding issues can degrade the
noise immunity of the pair to the point where external noise
sources that would not normally have an impact become a
significant problem.