256QAM simply allows for more throughput per downstream channel than 64QAM does. This doesn't mean that the customer will see faster speeds, it just means that there can be more people on one downstream channel, or the same number of people, but with higher downstream speed caps.

The downside is that 256QAM is more susceptible to noise, and hence requires better SNR and signal strength.

For a 256QAM modulated downstream channel, shoot for SNR above 33dB. Anything below may cause connectivity problems.

Thanks to oldTDNickell5

*This FAQ is based on user knowledge from a volunteer core of BroadbandReports' members. This FAQ in no way constitutes official information from Comcast or any of its affiliates.

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by Nerdtalker edited by Johkal
last modified: 2008-11-01 14:57:59