Q1. What is
is the abbreviation for Asymmetric Digital Subscriber Line. This technology
allows us to use the remaining bandwidth of a standard telephone copper
cabling. While the POTS ( Plain Old Telephone Service ) uses the frequencies
between 300 and 3100Hz, the higher frequencies normally remain unused.
ADSL uses the frequencies between 30KHz and 1.1MHz to transport data,
e.g digital data.
Q2. Why asymmetric?
typical residential user downloads more (e.g. surfing to a website) than
uploads to the Internet (e.g. sending a mail). It is therefore better
to divide the available capacity of the line asymmetrically.
Q3. How fast
theoretical limits are 1 Mbits/s for upload, 8 Mbits/s for download. The
real speed you'll get depends on a lot of factors: the contract with your
ADSL Operator/ISP, the interface between the modem ( Ethernet, USB...
) and your computer settings and capabilities, what software package you
are using and the distance to the exchange.
Q4. What ADSL
standards are supported by the SpeedTouch modems ?
SpeedTouch modems support the following ADSL standards:
- G.992.1 (G.dmt) standards information and G.992.2
(G.lite) standards information
- Full Rate ANSI TI.413-issue2
- ETSI TS 101 388( ISDN)
- ITU-G Handshake ( Automode ITU G.994.1 )
Q5. Does ADSL
interfere with the usual telephone service ? Can I still use my normal
works on totally different frequencies than the classic telephone services,
and as such, the two can be used at the same time. The only limitation
is that the user will need filters to avoid interferences between the
two services. A classic modem can still be used to allow small-band connectivity
to the Internet or to send faxes.
Q6. Can I
fax with my ADSL modem ?
uses other frequencies than the classic telephone services. If you wish
to use Internet services to send a fax, you may do so through your ADSL
connection. Otherwise, you'll need a normal modem of telefax machine to
send faxes the classic way.
Q7. Can I
use ADSL on my ISDN line ?
the ADSL technology has been adapted to be used over a ISDN ( digital
) line. Because the ISDN uses more bandwidth than the normal POTS services,
there will be less frequencies available for ADSL, which means the theoretical
speed limit of ADSL will be lower over ISDN than over a normal line. Usually,
the end-user won't feel the difference.
Q8. What are
the differences between the many xDSL variations ?
most used variations are: