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From: jbn@glacier.STANFORD.EDU (John B. Nagle)
Newsgroups: comp.windows.misc,comp.sys.next,comp.sys.mac
Subject: Re: replacing the desktop metaphor
Keywords: desktop metaphor, graphical interfaces, computing environments
Message-ID: <17988@glacier.STANFORD.EDU>
Date: 8 Jan 89 19:36:17 GMT
References: <4362@pitt.UUCP> <257@gloom.UUCP> <82702@sun.uucp> <8939@ut-emx.UUCP> <3504@geaclib.UUCP> <18640@agate.BERKELEY.EDU> <2643@xyzzy.UUCP>
Reply-To: jbn@glacier.UUCP (John B. Nagle)
Organization: Stanford University
Lines: 34

In article <2643@xyzzy.UUCP> meissner@xyzzy.UUCP (Michael Meissner) writes:
>Part of the radio spectrum is reserved for RF devices in an
>unregulated fashion and is used for cordless phones and such.

      Cordless telephones require FCC type approval.  See
47 CFR 15.231 - 15.237.

      Low-power communications devices in general are regulated under
47 CFR 15, subpart D.  There is a band reserved for low-power non-voice
devices between 26.99MHz and 27.26MHz.  RF bandwidth is restricted to
20KHz, and power to 10,000uV/m at 3 meters.  Model R/C gear used to use
this band, but that activity has mostly been moved to the 72MHz and 75MHz area.
Some of the cheaper radio-controlled toys still use the 26MHz band.

      It appears, suprisingly, that type approval is NOT required in
this band.  So it is a candidate for within-room wireless data transmission.

      Other users use this band, so interference is to be expected.  However,
there are six channels in the band, and the regulations allow operation on
"one or more" of them.  So it would make sense to have a system which
changes frequency when interference is encountered.  Sort of like a
frequency-hopping ALOHANET.

      This could all be made to work, but packing it into a keyboard
might require some semicustom ICs.

      Bear in mind that the channels in this band are rather narrow.
Wireless keyboards, yes.  Printers, maybe.  Graphic displays, no.  Disks, 
no way.

					John Nagle


					John Nagle