From: hoz@univel.telescan.com (rick hoselton)
Date: Fri, 16 Feb 1996 11:36:19 +0800
To: lwp@conch.aa.msen.com
Subject: Re: Using lasers to communicate
Message-ID: <9602152017.AA17834@toad.com>
MIME-Version: 1.0
Content-Type: text/plain


At 10:38 AM 2/14/96 -0500, you wrote:
>This idea of sending data via laser beams across open spaces has some
>very useful potential.  ...

>Eavesdropping and channel-blocking and physical-location-discovery are 
>related threats to which most traditional data channels are susceptible.  
>Any link which depends on a physical conduit (phone line, fiber, coax)
>is relatively easy to interrupt and to trace to its end points.
>RF links, even with frequency hopping, are subject to triangulation and
>jamming.  All these kinds of links can be eavesdropped.

>Point-to-point conduitless laser signalling, as envisioned by "Bill" and
>Tim in their quotes below, eliminates or reduces these threats

Dust will cause diffraction of the beam (at a reduced intensity, of course).  
Near the source, a detector tuned narrowly to the wavelength of interest would 
probably succeed quickly.  If you have a line of sight channel, there are 
many other ways to signal that will preserve some deniability.


Rick F. Hoselton  (who doesn't claim to present opinions for others)