Path: utzoo!mnetor!uunet!husc6!bloom-beacon!gatech!mcnc!unccvax!dya
From: dya@unccvax.UUCP (Edison Carter)
Newsgroups: sci.electronics
Subject: Re: low power license free packet?
Message-ID: <927@unccvax.UUCP>
Date: 7 Mar 88 14:03:46 GMT
References: <17327@glacier.STANFORD.EDU> <1004@bcd-dyn.UUCP> <4726@ecsvax.UUCP> <5661@cit-vax.Caltech.Edu>
Organization: Univ. of NC at Charlotte, Charlotte, NC
Lines: 104

In article <5661@cit-vax.Caltech.Edu>, peting@cit-vax.Caltech.Edu (Mark Peting) writes:
> I recently proposed the use of UHF television channels for packet radio
> and saw a posted response/flame from David Anthony article <918@unccvax.UUCP>
> with some criticism of this idea.
> 
(First point omitted for brevity)
>   1) Channels which could be used for other services that
       ate not, rather than channels without a UHF signal
    
     Obviously, I did not make myself clear. The allotment of a given
full service TV station precludes up to 14 channels from being used
in a given service area.  This is because of both interference caused
and interference received.
 
    Now, if you are talking about using **unoccupied** UHF channels
which are either in the Table of Allotments (a table showing where
UHF channels can be applied for) or could work in the Table of Allotments
(requiring a Petition for Rulemaking), then packet radio would be OK
provided that all the little packet radios go away when the full power
UHF goes on the air.

     However, lets talk about the two hundred and something Arbitron
television markets.  I know of precious few UHF allotments in any
metered market which are unapplied for (unoccupied, but not unapplied
for).  Most unoccupied channels are only unoccupied because several
mutally exclusive applicants are vying for that channel.  The unused
UHF capacity you speak of **does not exist**, at least where people
exist.

     Now, in North Carolina, the following UHF's are unoccupied at
present:

     High Point    67
     High Point   *32   * means educational
     Rockingham    53
     Laurel Hill   60 ?
     Morganton     23
     Manteo         4  (vhf)
     Kannapolis    64

     Of these, they are all in comparative hearings except for 
Laurel Hill and Rockingham, which are unapplied for, are in the
boonies, and couldn't possibly support low power packet. High Point
is dark.

     What my beef is, is that there is no unused UHF spectrum, a fact
which no one seems willing to concede.  What little UHF spectrum there
is "unoccupied" is usually occupied by translators and LPTV's. These
are duly licensed services which are in the public interest, convenience
and necessity.

     The unused UHF-TV spectrum will be shortly used, to be sure, and
thus, there is no time, or need, to develop radios which can't be
used in 99.9% of the television markets in the US.

***** PROPOSAL *****

      However, since there seems to be a strong low power packet
faction out there, I do have a proposal:

      1) Allow licenseable entities to apply for a LPTV license in
a given community, giving full no-offset protection to all cochannel
stations (and meeting all other separation criteria). Upon a grant,
allow them to distribute and operate low power packet radios within
their interference-free contour.

      2) Allow the use of Channel 38, which is reserved for radio
astronomy, for low power packet, except within 100 miles of established
radio listening posts.

      3) Move low power packet to the band occupied by the FM2 proposal
(220 to 225 mHz)

      4) Allow low power packet to operate between channels 4 and 5.
      5) Allow low power packet on the ISM (Industrial, Scientific
and Medical) frequencies.

*****

     I don't want a shouting  match either, but the encroachment of
the UHF broadcast spectrum is a matter which I will highly defend,
as a licensed broadcaster who is taking the risk to serve the public
interest.  

     The FCC would have no way to publish where packet radios would
not cause any harmful interference.  The reason is that this data would
be so massive, it would require a hand cart to transport it all in
boxloads.   When I have run UHF LPTV studies on every channel at just
** one ** location, it is about 175 pages of useful data. This costs
about $300.  Secondly, if someone did publish such data, the LPTV 
interested parties would snap it up and apply for even more LPTV
stations.

      There are precious few unapplied for channels in the USA. If
you don't use regular protection criteria, then you must revert to
LPTV rules.  The D/U ratio for interference is a matter of radio
physics, not one of what service is being carried.  In general,
a cochannel signal of 19 dBuV or better WILL CAUSE INTERFERENCE TO
A UHF STATION AT ITS GRADE "B" CONTOUR.  

     What about spread spectrum in the lower sideband?

David Anthony
DataSpan, Inc