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Old 25-04-2012, 12:34   #22
Ignitionnet
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Location: Leeds, West Yorkshire
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Re: what are ideal power levels and snr

Quote:
Originally Posted by Sephiroth View Post
As per Mon General's post. Stick it on if power rises to 11 dBmv or higher and let us know. That level is unhealthy because when you have 8 downstream channels, that would hit the DOCSIS 3 input maximum for a cable modem.
Nah, 8 channels = 2^3, so total power = 11 + 3 + 3 + 3 = 20dBmV, very short of the maximum 33dBmV.

Each doubling of channels increases total power by 3dBmV on the logarithmic scale, so even if the power were perfectly balanced to break 33dBmV with an average power of 11dBmV you'd be looking at bonding 256 channels, 256 channels at 11dBmV average giving 11 + (3 x 8) = 35dBmV, the 3 x 8 is due to 256 being 2^8.

Across 8 channels you actually need an average power of 24dBmV per channel, a tad outside the specifications.

EDIT: Which is what you said in the post before this one, I'm guessing you had an off moment on the post I quoted there
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