Peter
Guest
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 Posted:
Mon Feb 28, 2005 8:01 am Post subject:
Re: Why different upload/download speeds? |
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Hi Pete,
| Quote: | It just dawned on my that my new Covad account has an upload speed of 128k and a
download speed of a thousand-and-something k.
There's got to be a business reason, but what?
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Its to do with the signaling technology employed for ADSL. The general
idea is that Home users will want to download more data faster than
they will want to upload, so the service is "Asymmetric" in that
regard, big download bandwidth and small upload bandwidth as the user
sees it.
Now it just so happens that this also fits well with transmission line
theory that is present with the physical wiring of telephone exchanges
(the CO buildings in North American speak). There is a great density
of Copper going into ONE building, so the chance of "cross-talk" or
interference between the copper pairs is much higher at the exchange,
while each Home end has only a small amount of copper so cross-talk is
low. That means it is easier to "read" a weak signal at the Home, than
it is to "read" the same signal at the exchange building. If the
signal heading into the exchange is only low speed (relative to the
outbound signal), its easier to read than a high speed signal.
If you want equal speed connections, then you need an SDSL service,
where both directions are the same speed or are symmetrical. Needless
to say, many providers don't like doing SDSL because they can't put
too many SDSL services in one copper cable, they end up swamping each
other out...
Cheers......................pk. |
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