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telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15

2 edits
reply to NetFixer

Re: [Connectivity] Net Drops Constantly

Given the variations in the architectures of and equipment used in the various HFC systems Comcast has cobbled together over the years, I would think it is also possible that in some systems (like yours), upstream power levels of 51 dBmV or slightly more may not be a problem, while in other systems (like in ExoticFish See Profile's and owlyn See Profile's), levels that high do cause issues.

The differences between different brands/models of modems can also enable some of them to perform OK at >50 dBmV levels.

Like they say - YMMV.

EDIT: Looks like the upstream power limit is determined by the modem and, as some posters have stated before, the number of upstream channels. From page 3 of the data sheet for the Moto SB6121 (»www.motorola.com/staticfiles/Sup···heet.pdf ):

Upstream Operating Level Range Level range per channel:

(Multiple Transmit Channel mode disabled, or only Multiple Transmit Channel mode enabled with one channel in the TCS)
TDMA
Pmin to +57 dBmV (32 QAM, 64 QAM)
Pmin to +58 dBmV (8 QAM, 16 QAM)
Pmin to +61 dBmV (QPSK)

Level range per channel (two channels in the TCS)
TDMA
Pmin to +54 dBmV (32 QAM, 64 QAM)
Pmin to +55 dBmV (8 QAM, 16 QAM)
Pmin to +58 dBmV (QPSK)

Level range per channel (three or four channels in the TCS)
TDMA
Pmin to +51 dBmV (32 QAM, 64 QAM)
Pmin to +52 dBmV (8 QAM, 16 QAM)
Pmin to +55 dBmV (QPSK)