Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site watcgl.UUCP
Path: utzoo!watmath!watcgl!dmmartindale
From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.lan
Subject: Re: Ethernet cable length query
Message-ID: <2318@watcgl.UUCP>
Date: Mon, 26-Mar-84 14:25:25 EST
Article-I.D.: watcgl.2318
Posted: Mon Mar 26 14:25:25 1984
Date-Received: Tue, 27-Mar-84 01:24:04 EST
References: <6130@umcp-cs.UUCP>
Organization: U of Waterloo, Ontario
Lines: 7

When the cable goes open, you can't talk to it at all.  When a transceiver
transmits, its output has a DC offset as well as an AC signal component.
This is used for collision detection, since DC from two sources adds in
a much more predictable way than two sources of AC.
If one of the terminators is missing, the DC offset on the cable is twice
what it should be for a single transceiver transmitting, and the transceiver
detects it as a collision.