Triple-Play Service Deployment

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Chapter 4: Troubleshooting the Copper Plant for IP Services
For providers deploying higher-speed data or triple-play services,
a test set that is capable of performing a spectral noise analysis up
to 30 MHz should be used in order to support analysis of noise
across the ADSL and VDSL frequency spectrums. This is critical for
two reasons. First, the frequency ranges supported on many older
test sets typically top out at or just beyond the upper limit of the
ADSL frequency spectrum and do not fully address the ADSL1/2/2+
and VDSL1/2 spectrums. Second, and more importantly, the potential
negative impact of excessive noise on ADSL and VDSL circuits
carrying triple-play services is far greater than for traditional lowerspeed
or “best effort” Internet data service over xDSL. While some
loss of data rate due to excessive noise was tolerable or even
unnoticeable to traditional xDSL Internet data service users, packet
loss or slower data rates due to noise on IPTV service can damage
the QoS causing pixelization and frame freezes leading to a
negative customer experience.
Ideally, the spectrum analysis measurement should also support
analysis down to a noise floor that approximates or approaches
normal ambient noise conditions on twisted pair plant—typically
around -140dBm/Hz. This is important because noise levels are
rarely static and often fluctuate with time, the source, or varying
environmental and plant conditions. For example, it is very useful
to be able to identify a potential source of interference that is
present even if its magnitude at the time of testing is not
significant enough to impair the xDSL service. As additional xDSL
pairs are brought on line within the same cable or plant conditions
worsen, the impact of the interference source could begin to be
noticed in the form of errors, lost packets, and/or lower data rates.