Troubleshooting guide

Troubleshooting the CMTS
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1. Inspect optical amplifiers in the HFC network to make sure they are working
properly.
2. Make sure all HFC network equipment is working properly.
3. Inspect cables for damage.
4. Secure all cable connections.
5. Review the HFC network topology and identify any flaws that may cause
additional ingress.
6. Determine if there are too many nodes on an upstream port. Too much
segmentation can affect the signal-to-noise ratio.
7. Check the individual nodes on an upstream port that is experiencing ingress
problems. For example, three nodes may have an acceptable signal-to-noise
ratio, but the fourth node might have a bad signal-to-noise ratio that is
cascading into the other three nodes and causing poor performance on the
upstream port.
8. Determine if impulse and electrical ingress noise is entering the network from
electrical sources within a home (such as hair dryers, light switches, and
thermostats), or from high-voltage lines near network cabling.
Upstream Power Level Too Low or High
The cable interface controls CM output power levels to meet the desired upstream
input power level. Input power level adjustments to an operational upstream port
compensate for cable headend path loss between the optical receiver and the
upstream RF port. This section describes how to troubleshoot physical problems
that may affect power levels on the upstream channel.