User's Manual

Vyyo Installation Guide
www.vyyo.com
WMTS US Port Mapping – p. 116
Chapter 9. Maintenance and
Troubleshooting
9.1 Introduction
The WMTS is an IP centric two-way RF system, which incorporates various
information technologies and RF devices. When the system is not operating
properly, the malfunction must be isolated to localize the problem to a single
functional area.
The troubleshooting process consists of three basic steps:
• Identifying the problem,
• Diagnosing the problem, and
• Implementing a solution.
To identify a problem, you have to ask two questions:
1) When does the problem occur?
2) What else is affected?
For example, when none of the modems respond to an SNMP request, it can be
assumed that the WMTS or the RF components at the base station are not
functioning properly. Try to find out if the problem is on the downstream or
upstream path. If only a certain modem does not respond, it can be assumed
that the problem relates to the subscriber site, or an NMS software setting for
that particular subscriber.
If you have identified the problem, you are ready to diagnose its cause and take
the necessary actions to solve the problem.
When implementing solutions, change one thing at a time, if possible. If the first
solution does not solve the problem, reverse the change you just made and try
another solution. For example, you are experiencing problems in one of the
upstream sections. To solve the problem, replace the demodulator card. If the
problem still remains, replace the old card and try another solution.
Some of the symptoms can be related to a certain functional area, some not.
Use the system block diagram in the next section Troubleshooting the RF
Frontend to relate the problem to a certain area.
9.2 Troubleshooting the RF Frontend
9.2.1 General
The RF frontend contains the upstream and downstream channel converters and
amplifiers.