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From: m21198@mwvm.mitre.org (John McHarry)
Newsgroups: comp.dcom.telecom
Subject: Re: Phone Calls at the Speed of Light
Message-ID: <3612@accuvax.nwu.edu>
Date: 6 Feb 90 23:11:21 GMT
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X-Telecom-Digest: Volume 10, Issue 83, message 5 of 8


Tom Roberts wrote in V10 #77 that '...signal delay is only a minor
consideration when telcos engineer a transmission path...'.  While
delay in the cable or fiber may, indeed, be overwhelmed by the other
delay modes he mentioned, the total delay is not a minor
consideration.  It is at the heart of the 'via net loss plan', to
which I am sure he can find a couple references in his company's
library.

Very roughly, the aggravation caused by echo is affected by the round
trip delay.  To partially circumvent this, more loss must be added on
long paths than on short ones.  Also, there are 'cross office delay'
specs on switching equipment to ensure that it doesn't mess up the
scheme.  Sometimes echo suppressors or echo cancellers are required on
very long delay paths.

And that's the news from the bottom of the rain barrel, where no one
has reviewed this but me and my echo...echo...echo...

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* John McHarry    (703)883-6100             McHarry@MITRE.ORG *
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