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From: jimbi@copper.UUCP
Newsgroups: comp.dcom.lans
Subject: Re: Ethernet : Broadband vs Baseband
Message-ID: <887@copper.TEK.COM>
Date: Mon, 23-Feb-87 16:10:34 EST
Article-I.D.: copper.887
Posted: Mon Feb 23 16:10:34 1987
Date-Received: Fri, 27-Feb-87 00:26:02 EST
References: <2334@sunybcs.UUCP> <18500001@clio> <14863@amdcad.UUCP> <3164@osu-eddie.UUCP>
Organization: Tektronix Inc., Beaverton, Or.
Lines: 33
Summary: Maintenance headaches with broadband

---- 

Here at tektronix, we have both broadband and baseband.  From my
observation of both systems I have formed the opinion, if you don't have RF
engineers to maintain and tune the broadband system, your in trouble.  When
one system was laid out, here at Tek, taps where planned on 40 foot centers
and the attenuation both downstream from the taps in the broadband and at
the taps was carefully accounted for.  When the system grew to need more
taps then those present, the whole system had to be reworked to account for
the attenuation present from extra taps.  Contrast this with baseband where
taps may be installed by people without RF training, in any order or time
frame up to the limit of the maximum number of taps for a given length of
cable.  If the demands on the baseband system grow too large then another
hunk of cable can be installed and the two nets connected with a repeater
or bridge (depending on the overall size).

Certainly, more networks may be placed on the same piece of cabling, simply
by having one set of talking and listening frequencies for one network and
another set for another network.  However, the non-trivial task of
designing, setting up the headend, and maintaining the RF characteristics
of the broadband seem to out wieght the gain of multiple nets on the same
cable.  A special hunk of hardware is needed to map the different nets
frequencies into each other, should you ever want to have the nets to talk to
each other.  I'm sure that some sites have the expertise available, so this
would not be to hard.  But other sites exist where this experience is not
there.  These sites could install a baseband system and keep it going with
less difficulty then a broadband system.

Jim Bigelow
CASE Division
Tektronix, Inc.

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