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From: knop@duteca.tudelft.nl (P. Knoppers)
Newsgroups: comp.dcom.telecom
Subject: Re: Cleaning Pulses
Message-ID: <9795@accuvax.nwu.edu>
Date: 16 Jul 90 14:02:51 GMT
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Reply-To: Peter Knoppers <knop@duteca.tudelft.nl>
Organization: Delft University of Tech, Dep. of Electrotechnical Engineering
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X-Telecom-Digest: Volume 10, Issue 489, Message 8 of 10


In article <9677@accuvax.nwu.edu> ah0i+@andrew.cmu.edu (Andrew A.
Houghton) writes:
>X-Telecom-Digest: Volume 10, Issue 479, Message 5 of 14

>In brief, I have heard that at one time AT&T sent out "cleaning
>pulses" in the wee hours of morning to "fuse shorts in the line."

>Assuming this is drivel, is there any basis for such a thing?
Yes and no...

The yes part:
Phone companies (at least in The Netherlands) regularly test
subscriber lines using voltages up to several hundreds of Volts.
Subscriber equipment is designed to survive such tests. The tests
are carried out with no (or almost no) human supervision. Lines that
happen to be in use during the test are skipped.

The no part:
I don't think that the phone company expects to cure faults in the
isolation of the subscriber loops. It might work for a while if you
are lucky, but the line will never become reliable again. The aim of
these test is to detect problems before regular service is hampered.


P. Knoppers, Delft Univ. of Technology, The Netherlands, 
knop@duteca.tudelft.nl