Alcatel Carrier Internetworking Solutions SpeedTouch Speed Touch Home Asymmetric Digital Subscriber Line (ADSL) Modem - Manual (Page 11)

2 Speed Touch Home Tour
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3EC 17058 AAAA TCZZA Ed. 02
2.2 Speed Touch Home at a Glance
2.2.1 ADSL Exposed
ADSL is brandĆnew modem technology, used by the Speed
Touch  Home, unlocking the potential bandwidth of the widely
available public telephone network.
ADSL is short for Asymmetric Digital Subscriber Line. This
somewhat cryptic name is best explained in straightforward terms:
"
Line: Because ADSL uses the ordinary existing copper line,
known as local loop", that runs between your home or office
premises and one of the telephone operators' main switching
exchanges, known as a central office.
"
Subscriber: That's you. Because this is what service providers
or operators call their customers or end users.
"
Digital: Because ADSL is used to transmit digital signals, just like
those that make up computer files.
"
Asymmetric: Because ADSL can transmit data much faster from
the Internet towards the end user than the other way around. It
is rather like having a major highway in one direction and a
oneĆlane road in the other.
Because Plain Old Telephone Service (POTS) and ADSL occupy
distinct frequency spectra (See figure 2), ADSL service can coexist with
conventional telephone service.
ADSL
UPSTREAM
ADSL
DOWNSTREAM PO
TS
ISDN
125kHz 207kHz 272kHz 1.1MHz 80kHz
adsl 0783/ 01
Figure 2 POTS and ADSL Frequency Spectra