Path: utzoo!mnetor!uunet!husc6!bbn!uwmcsd1!ig!jade!ucbvax!hplabs!decwrl!labrea!paulf@umunhum
From: paulf@umunhum.STANFORD.EDU
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Ethers, Copper, Fiber, Microwaves, Etc.
Message-ID: <120@umunhum.STANFORD.EDU>
Date: 11 Dec 87 19:01:09 GMT
References: <16836@bu-cs.BU.EDU> <8712101810.AA00864@PTT.LCS.MIT.EDU>
Reply-To: paulf@umunhum.UUCP (Paul Flaherty)
Organization: The Three Packeteers
Lines: 29

In article <8712101810.AA00864@PTT.LCS.MIT.EDU> dab@ALLSPICE.LCS.MIT.EDU writes:
>	In the ham radio community for several years there have been
>devices called Gunnplexers available (I don't know if that's a brand
>name or a generic name) which are a 10 GHz microwave system for about
>$200.  When they first showed up there were several articles in ham
>radio magazines descibing how to send video through them, so 10 Mb/sec
>is probably not too far out of line.  Except for maybe the feedhorn
>(or the dish itself) it would easily fit into a briefcase.  The range
>is limited but I think to line of sight rather than 1 mile.
>						Dave Bridgham

	The biggest problem with using GunnPlexers (TM) for digital 
communications is their lack of linearity.  GunnPlexers have both phase and
amplitude distortion, and have some real temperature - frequency dependence
problems.

	Despite this, by using FSK or MSK combined with some equalization, one
can make an incredibly cheap digital link.  We're currently working on a modem
that uses temperature stabilized GunnPlexers, and MSK with some simple 
adaptive equalization, to be used by the 230.4kbps AppleTalk protocol.

	Look for the article in the March '88 issue of _MacWorld_.



-=Paul Flaherty, N9FZX		 | "The only thing that we've learned from
Computer Systems Laboratory	 |history is that we havn't learned anything
Stanford University		 |from history..."
Domain: paulf@shasta.Stanford.EDU|		-- William Jennings Bryant