Visualots Pre-Equalization

How to find RF noise in a cable plant based on the modems pre-

equalization levels in real time.

Starting at 12:30 we had a massive issue with codeword errors on Node 1.

Bringing up Visualots map of node 1.

Node 1 Launch amp.

Graph the frequency response from the first device off each line.

In the frequency response graph look for modems that are grouped together. If you notice the circled area they all share

the same signature. Red is after the device, while blue is on the node.

Check the main lines from the launch amp until the signature shows up in red.

As you can see the problem we are tracing is past the selected device in the last slide.

Continue to check branch’s to verify/eliminate it as the problem area.

As you can see the problem is not down this leg of the plant.

Every time the main line branch’s you need to verify its not down that leg.

If the signature shows up in blue that area is clean.

By eliminating 95% or more of the node it increases your MTTR without moving a

vehicle.

This area is suffering from a similar problem that we are looking for. This could be part of the same problem, or a separate one. In order to

find out we need to find modems on the other legs that are not affected.

The highlighted device only services one customer. If this modem is responding properly we should be able to identify that

the other problem is separate from the main issue.

The modems past that device seem to be responding very nicely. This would suggest that we are dealing with two different

problems and should continue down the line to find the one affecting the most customers.

With only 1 split past this spot we should make sure we still have some good responding

modems behind it.

As you can see there are some modems still responding out of the signature we are hunting. This tends to tell

me the problem is still further down the line.

This is the last split on Node 1. Lets see if any modems past here are responding properly.

As you can see there are some modems that are definatly part of it, and some that might or might not be part of it. In order to

verify we should check on either line from the split to see if the modems on either side are all in the bad signature.

Quick check of modems past this device.

One of the modems does, while the others is on the edge.

Check the other half of this area.

Modems past this device are falling into the signature as well.

Based on the response of the modems I would start looking for the problem at the circled devices.