Triple-Play Service Deployment

Chapter 5: Troubleshooting the Premises Wiring
The ingress resistance/noise immunity test looks at a disconnected
cable system to determine if any external carriers are present in the
FM Band. If there are carriers present above a predetermined level,
then the household will be susceptible to allowing ingress into the
plant, which may cause video or data transmission problems.
The fact that ingress in the DC-45 MHz band is intermittent and
requires more than a cursory glance with a spectrum analyzer is
supported by experience with the JDSU PathTrak spectrum
monitoring system. This system continuously scans the 5-65 MHz
band and provides statistical reports of the return path ingress
and noise performance over time. Figure 5.11 shows a
performance history scan of a reverse path node that had
intermittent ingress problems. Note the time dependency of
noise. The noise in the 5-45 MHZ band is much higher and
problematic from 4:00 to 8:00 in the evening—typically service
technicians are not troubleshooting at this time.
Figure 5.11 Time summary of ingress on a coaxial network. Performance summarized by 1 hour
averages over 24 hour period.
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