Page 28 - Broadband Internet The Basics for Next Generation Networks (NGN) in Telecommunication.
P. 28
SELF-ASSESSMENT
EXERCISE
Question??
3.
ADSL is one of the technology used for broadband
services by using the available un-used local loop
or subscriber loop, bandwidth. With the aid of an
appropriate diagram show this technology bein
implemented in data transmission and
reception without affecting the transmission of
a voice traffic.
Answer!!
The above diagram is ADSL frequency band. The physical layer of ADSL is designed
to be able to coexist with standard POTS spectrum. The two services can coexist
because ADSL is using a higher frequency spectrum than the baseband spectrum
used for POTS.
The ADSL uses spectrum between 25kHz and 1104kHz for downstream.
The lower band between 25kHz and 138kHz is used for upstream.
The frequency dedicated for voice in POTS is 0.3-3.4kHz, but the bandwidth
between 3.4 and 4.0kHz is needed as guard band.
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