Quote:
Originally Posted by Kushan
Cable/DOCSIS adapts to line conditions in much the same way ADSL does, we just don't see a "Sync" rate that declines, instead we see things like QAM dropping to QPSK and the like.
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When was the last time your downstream channels dropped to 64QAM?
If you were to say have a huge burst of noise in the middle of an upstream channel that produced a negative SNR would it be able to adapt?
A single narrowband burst of noise will cause a loss of 50% of the capacity of an upstream channel. On xDSL this would be a far smaller effect as it uses DMT.
Your 'sync rate' declines it just isn't displayed. The added bonus is of course that impediments anywhere on the node can cause it to drop as, while you do have coax not twisted pair, you are also on a shared access segment with however many other hundred people.
Cable has its own set of issues. xDSL was built to run on unshielded twisted pairs in an unpleasant environment. Cable relies on being a closed network with constant maintenance to remove ingress.