Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!ucsd!ucsdhub!hp-sdd!hp-pcd!hpvcfs1!johne
From: johne@hpvcfs1.HP.COM (John Eaton)
Newsgroups: sci.electronics
Subject: Re: 2 way IR LED systems
Message-ID: <1430010@hpvcfs1.HP.COM>
Date: 22 Feb 90 00:15:23 GMT
References: <431@skipper.dfrf.nasa.gov>
Organization: Hewlett Packard, Vancouver, WA
Lines: 26

<<<
< Is there any reason Infrared LED systems can't be 
< used for 2-way communication?  It seems like this
< would be easy if different frequency carriers were
< used for transmit and receive.  (I'm not sure how
< those IR headphone systems work - do they use 
< carriers?)
----------
My understanding of the state of the art in optics is that
they are still at the same level as spark gap transmitters
were in the RF arena. The detectors cannot be tuned to different
frequencies of light. 

One system that might work is to have a master station broadcast
a clock and sync signal to everyone in sight. The slave stations
could then jump into selected time slots and send packets up the
the master. 

All this IR talk reminds me of the PCjr. They put an IR "Freeboard"
on a computer designed for the home/education market only to find
that they would not work if you put several in the same room. Talk
about product planning.


John Eaton
!hpvcfs1!johne