Path: utzoo!attcan!uunet!lll-winken!ames!pasteur!ucbvax!hplabs!hpda!hpdslab!hpdsla!davew
From: davew@hpdsla.HP.COM (Dave Waller)
Newsgroups: comp.sys.mac
Subject: Re: Re: replacing the desktop metaphor (airplane throttles)
Message-ID: <1370017@hpdsla.HP.COM>
Date: 12 Jan 89 16:22:44 GMT
References: <1611@ssc.UUCP>
Organization: HP - Pacific Technology Park
Lines: 22

Well, for thoseof you who want a more technical explanation, those rock band
wireless mikes and such use a concept call Frequency Division Multiplexing
(FDM) to allow for the simultaneous transmission of each device without
interference. This sounds high-falootin', but it really is the same concept
that allows several radio stations in the same geographical are to transmit
without interfering with each other -- each one transmits ona different
frequency, and you adjust a tunable bandpass filter and amplifier (i.e.
your radio reciever) to the frequency you want to recieve.

A multi-computer environment with wireless keyboards would have to work in
much the same way. Allocation of frequencies would be nearly impossible without
some rather sophisticated electronics to "select" an unused channel for the
keyboard. RF communications takes too much power anyway, so your keyboard
would have to have some hefty batteries.

Dave Waller
Technical Computer Group
Hewlett-Packard Co.
Pacific Technology Park
Sunnyvale, CA
(408) 746-5324
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