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From: zemon@fritz.UUCP (Art Zemon)
Newsgroups: net.dcom
Subject: Having trouble with a cable under a parking lot
Message-ID: <1600@fritz.UUCP>
Date: Wed, 16-Jan-85 16:23:17 EST
Article-I.D.: fritz.1600
Posted: Wed Jan 16 16:23:17 1985
Date-Received: Sun, 20-Jan-85 07:57:28 EST
Organization: FileNet Corp., Costa Mesa, Ca.
Lines: 36

I just installed a cable between two buildings (under a
parking lot) and am very mystified by something.  There is
180 Hz, 0.5 V peak-to-peak triangular wave on the lines.
Does anybody have any idea what might cause this or how to
get rid of it?  Is this a "common" problem?

More information on my installation:

The cable is 12 twisted pairs of 22 guage wire.  Although
each pair is not shielded, the cable has a shield
consisting of braid and foil.  The cable shield is grounded
to AC ground at both ends.

The cable is about 600 feet long.

The cable runs through two electrical power distribution
rooms and past an industrial 480 V -> 208/115 V
transformer.  Remember, however, that the interferance is
triangular, not sinusoidal.

A 60 Hz signal is also apparent on the cable but is of much
lower magnitude (about 0.2 V peak-to-peak).

The total voltage of the interferance is up to about 0.7 V
and this is too high for me to run my Micom 400 local
datasets above 2400 baud.  What really bothers me about
this is that I had been running the same datasets over 6
*miles* of telephone company lines at 4800 baud without
problems.

Any help would be greatly appreciated!  Should you wish to
call, my phone number is (714)966-2344.
-- 
	-- Art Zemon
	   FileNet Corp.
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