Topband: QRM from DSL?

[Bill Tippett]

        One of my other hobbies is investing and one area I have some
holdings in is DSL (Digital Subscriber Loop) technology which facilitates
very high speed data (i.e. Internet) connections over standard twisted pair
copper lines.

        Here is an interesting patent held by Analog Devices/Aware:
 http://164.195.100.11/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1
&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1='6,088,390'.WKU.&OS=PN/6,088,390&RS
=PN/6,088,390

...and the excerpt I found most interesting:

"BACKGROUND OF THE INVENTION 

     The invention relates to a method and system which combines decision
feedback equalization and forward error correction to improve performance
in point-to-multipoint digital transmission systems. 

     Many channels used for digital data transmission subject the received
signal to a variety of sources of degradation, including Guassian noise,
time dispersion, and impulse noise. A twisted pair used for digital
subscriber loops is a particularly severe example of such a channel, where
non-stationary noise sources such as narrowband interference (induced by AM
radio, amateur radio)
and periodic impulse noise (e.g., due to light dimmers) can also be a problem. 
To achieve the desired performance, powerful signal processing techniques are 
required to recover the data. Two particular techniques that have found
widespread use is decision feedback equalization and forward error correction 
(FEC)."

        If this technique is susceptible to "AM radio and amateur radio",
I wonder it it may not also GENERATE reciprocal interference on Topband?
Has anyone experienced any problems with DSL interference on 160 yet?
Does anyone know if it has the potential to do so?  This technology will
become very commonplace over the next few years so let's hope not!  At
least it's nice to know someone has designed a technique to reduce
potential interference caused by 160 signals induced into phone lines.

                                                73,  Bill  W4ZV


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