CoxNVAHSI
Premium
join:2007-07-12
Locust Grove, VA
edit:
May 7th, @04:47PM
| reply to jsimmons
Re: [VA] Modem Boot Log Issues
Upstream DOCSIS spec for power is 27 - 54... the sweet spot is 41-48. Anything within 35-52 is fine. The closer you get to the extremes of the DOCSIS spec the more exposure you have in regards to seeing problems. The high end of that range is to ensure that the seasonal drift (temps rise, plant expands resulting in higher transmit)does not put you into a max transmit (55dB on many modems). There are also other design elements that go into it but I would be misrepresenting myself as I am not an RF engineer (I know where they sit though).
So on the upstream your power being low can cause a lot of problems due to being closer to the noise floor. You do not want to be down in the junk. Low Tx is just as bad if not worse (IMHO) than a high Tx. High Tx is a problem but more so when the modem is maxed out (i.e. the CMTS is Kirk and your Cable Modem is Scotty going... "She kinna take any more, Captain. If I give her inny more she'll blow!". Unlike Scotty... your modem knows it's limitations and will not pull a solution out of thin air when asked to tx more than it is designed for.
If you do not get the reference... ask someone that looks older than you to explain. |
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jsimmons
Premium,MVM
join:2000-04-24
Falls Church, VA
 ·Cox HSI
| Good explanation 
I have always had great service with upstream levels of 38-40. I can say for sure - once it hits 50, problems are not far away.
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"Everything should be made as simple as possible, but not one bit simpler."- Albert Einstein |
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