A Frequency Domain Approach To Crosstalk identificaion in xDSL Systems

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Introduction to DSL


DSL :
High bit rate digital information over telephone subscriber lines
Basic types of DSL
> Basic Rate ISDN (up to 160 kbps)
> HDSL ( up to 1.544 or 2.048 Mbps)
> ADSL (up to 1Mbps(u.s) ,9Mbps(d.s))
> VDSL (up to 52 d.s and 6.4Mbps u.s)

Why Noise Estimation?


Tele phone cables gives rise to a series of impairments at broad band range

Noise occurs because of imperfect balance

Balance is function of frequency ,reduces with higher frequencies

There are 3 types of noises in DSL
>> Crosstalk
>> Impulse noise
>> Radio noise


Crosstalk


Definition :
“ Leakage into one channel of signal power from another channel.”
No two binder groups are adjacent for long runs, to minimize the crosstalk.
There are 2 types of crosstalk
>> Near End Crosstalk(NEXT):
It is the coupling between transmitters and receivers at the same end of a cable