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From: fmgst@unix.cis.pitt.edu (Filip M Gieszczykiewicz)
Newsgroups: sci.electronics
Subject: Re: tapping into a fiber optic cable
Message-ID: <24677@unix.cis.pitt.edu>
Date: 4 Jun 90 04:54:45 GMT
References: <46249@iuvax.cs.indiana.edu> <151@coplex.UUCP> <994@tsdiag.ccur.com>
Reply-To: fmgst@unix.cis.pitt.edu (Filip Gieszczykiewicz)
Distribution: all
Organization: The Last Jedi
Lines: 31


	Greetings. About 20% loss if bent...

	What you people don't realize is that one can very easily
	protect against someone bending the cable..

	Simply have 2 pots (or a more complex circuit) and preset
	the INTENSITY of "1" and the intensity of "0"... That is,
	don't make "1" be FULL ON and "0" FULL OFF. What you want 
	is a loop with a serial word "looping" in the cable. If
	someone bends the cable, either the "1" or the "0" will 
	not have the same level... partity error is detected and
	"all hell breakes loose" :-) 

	If the serial reciever/transmitter is fast enough, you don't
	even need a partity checker, just a plain comparator will
	do just fine. 

	Take care.

	P.S. Whay the whole mess of the serial I/O controller??
	Well, what is the potential "fiber bender" (like 
	"fender bender" ;-) prepared for? a simple on/off
	pulser and/or pressure jacket or for a complex
	sequence of high speed bits running along? I rest my
	case :-)
-- 
_______________________________________________________________________________
"The Force will be with you, always." It _is_ with me and has been for 10 years
Filip Gieszczykiewicz "..of future fame...." "Ok! So I have a dream..."
FMGST@PITTVMS  or  fmgst@unix.cis.pitt.edu "My ideas. ALL MINE!!"