Triple-Play Service Deployment

Chapter 4: Troubleshooting the Copper Plant for IP Services
Opens
Opens are conditions in which tip and ring are completely
disconnected because of a cable cut, storm damage, or damage
from animals. Finding opens is relatively easy. No receive signal is
detected and the DC path is broken. As a result, current is not
present. One-sided opens differ from complete opens in that one
wire, either tip or ring, is not broken. They are usually the result of
corrosion caused by a degrading splice or moisture on a cable.
However,a TDR sees a one-sided open as a complete open.Since the
wire is still connected, the TDR shows additional faults downstream.
Wideband Testing Considerations
With the increase in deployment of ADSL2+ and now VDSL2 in
order to offer high bit rate video services, the ability to address
testing across the full ADSL2+ and VDSL2 frequency spectrums is
a critical component when formulating installation and troubleshooting
test strategies and plans. Traditional, lower-speed, ADSL
Internet data service may not have always driven as strong a case
for wideband testing. Packet loss, packet jitter, momentary loss of
synch, or failure to maintain adequate bandwidth to support IPTV
can severely degrade video performance and, with it, customer
QoE. VoIP, while less sensitive to packet loss than IPTV and less
bandwidth intensive, is nonetheless delay sensitive. In short, IP
QoS problems (loss, delay, jitter, etc.), due to excessive wideband
noise or attenuation on the physical medium, may have been
acceptable for traditional ADSL-based Internet data service, but
now represent a critical area of risk when deploying and
maintaining triple-play service over DSL.
As noted throughout the preceding troubleshooting section,
traditional wideband test equipment may not address the
requirements of today’s ADSL2+ and, especially, VDSL2 circuits.
Test sets should support measurements across the full wideband
frequency range up to 30MHz for VDSL2. Additionally, the
appropriate filters for ADSL, ADSL2/2+, and the different VDSL2
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