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Old 13-01-2009, 20:29   #15
caph
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Re: 55 DbmV upstream power level

Quote:
Originally Posted by Broadbandings View Post
That sounds like BS to me. Doesn't make any sense at all that your upstream power would need to rise to accomodate 50Mbit and the DOCSIS 3 overlay.
Sounds like it could be BS to me too but the only logical conclusion to that is that service engineers deliberately lie to customers to fob them off. It's possible but it leaves a bad taste in my mouth. His words were more along the lines of - they're up to their neck in it and the power levels are all over the place and will be until they're finished.

---------- Post added at 19:29 ---------- Previous post was at 18:50 ----------

Quote:
Originally Posted by Broadbandings View Post
If bad downstream SNR were causing issues with upstream it would be because the modem were not seeing the periodic station maintenance responses from the uBR / CMTS, so it would increase transmit power thinking it was not being heard. When it did actually get a response from the CMTS it would be along the lines of 'Oi stop shouting, drop your transmit power down xdBmV' so I can't really see how it would reduce Tx power long term.

What it might resolve is large numbers of power adjustments due to the modem not seeing the range response from the CMTS and hence incrementing transmit power by the DOCSIS standard amount, however if the downstream path is so munted that the modem is missing large amounts of range responses and periodic station maintenances from the CMTS the upstream power is a total non-issue.

A connection that would suffer issues like this would be very, very broken indeed and upstream Tx power would be the least of worries on a connection like this. It would likely be too busy losing QAM sync on the downstream to be bothered what the upstream is doing.
Sorry to jump thread but you are almost exactly describing my current UCD problem apart from the downstream problem.

My event log is showing continual critical errors of "Started Unicast Maintenance Ranging - No Response received" followed by the UDC message. And my upstream power levels keeps getting higher and higher (hit 60db tonight). The only thing is my downstream power is 0.6 and my downstream SNR is a healthy 36.3. Can you think of any reason why my modem keeps shouting but not getting a reply?
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