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Re: Upstream Errors

Floyd,

We've run into quite a few of those issues over here over the summer, especially when we moved from 16 QAM to 64 QAM on the upstreamcarrier. You might get lucky and find a bad amp where it goes from good to bad within the cascade. However, in this business, it's nevereasy is it? So you'll probably have to do a little digging. Just an FYI: if you are using 16 QAM or 64 QAM, signal will be measured in MER because it is now digital.

Here's a suggestion:

Turn on your forward and reverse sweep. Start at the node to get your forward reference and your return telemetry as you normally would. Sweep the run in question. If you find any imperfections in the sweep picture (saw grass, jagged edges, high end roll off), get those cables replaced, because it will ABSOLUTELY affect your upstream MER.

Another thing we found is that bad cable at the start of the cascade will adversely affect CMTS receive MER towards the back of the cascade (funnel effect). Each bad span you pass through from beginning to end will add to the US MER and codeword issues at the EOL.

Another suggestion:

Another way to troubleshoot (it's a little more difficult, but it works) is with a test modem and a laptop. Test until bad and back up to find where the bad starts.

Good luck,

-J_r0kk
This is CABL.com posting #319793. Tiny Link: cabl.co/mbvl7
Posted in reply to: Re: Upstream Errors by harricanfloyd
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