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Reverse Path Troubleshooting: Problems in Advanced Services

• Compare the headend noise spectrum to the local spectrum. This allows

you to determine whether a problem you see in the field matches the

headend problem.

• Use Dwell Time in spectrum analysis. The more time a meter spends

looking for ingress, the more likely it is to catch a random/transient

problem.

• Fast scanning gets data in real time, and makes diagnosis much faster.

• Low-pass filters allow you to separate intermod problems from forward

channels so you can make a correct diagnosis of CPD.

• Use preamps so that you can use an amp test point and still see noise

accurately above the test equipment noise floor. This way, the reverse

network won't have to be taken down to get a high level signal for

analysis.

• Using the SDA-5000 means you have fewer things to carry, which in turn

means less work. Long battery life means fewer trips back to the

headend or truck for a new battery. Light weight means faster connection

times.

Tools for Combating Reverse Ingress

The following list outlines the tool options you can select for your reverse

path troubleshooting tasks:

• An SLM/sweep meter with spectrum display is the best solution.

• A spectrum analyzer with battery and filters means more stuff to carry,

but it still works.

• You can also use a spectrum analyzer in the headend, a spare video

channel, a modulator, and a TV. You'll have to disconnect the legs of the

return path and look at the noise to see if the problem went away. This is

the least desirable of your options because it creates service outages

and it doesn’t work very well.

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Wavetek 147 Especificaciones Pagina 123