Reverse Path Troubleshooting: Problems in Advanced Services
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For two-way systems, ingress and noise are far greater problems in the
reverse path than they are in the forward path. The reasons— accumulation
of noise, many diverse ingress sources, random noise, physical plant
problems, and CSO intermodulation—are fairly common:
• Accumulation of Noise: Accumulation of noise means that problems
compound far more quickly than in the forward path. In a forward path
network, noise or interference generated at one point in the network
affects everyone "downstream" from the noise source (see Fig. 5-1).
Fig. 5-1 Customers Affected by a Forward Path Ingress
Source
In order to limit these problems, hardline and better quality equipment
are used at the upstream connections, and less expensive equipment is
used downstream.
In the reverse path system, however, a noise problem affects everyone
in the same "leg" of the network all the way back to the headend receiver
(see Fig. 5-2). This means that the concept “quality first close to the
headend and cost first close to the customer” no longer works.
PROBLEMS IN ADVANCED SERVICES
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