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                      THE CGC COMMUNICATOR

                            CGC #321

                   Thursday,  April 15, 1999

                 Robert F. Gonsett, W6VR, Editor

     Copyright 1999, Communications General Corporation (CGC)

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  CONVERSATION TOPICS

  The NAB Convention is next week and it's time to look at a
few important issues.  For one, FMers are facing translator
encroachment and the possible creation of a Low Power FM service.

  On another subject, many engineers (both radio & TV) are
wondering what is so special about those shiny new digital audio
consoles that are costly and difficult to service, while the
human ear remains firmly implanted in the analog zone.

  On the TV side, a number of people are questioning DTV's use
of 8-VSB modulation which has proven to be anything but robust
with indoor receiving antennas.  Then there is Y2K.  Certainly,
everyone is concerned about that.

  This special issue of the CGC Communicator addresses three
of these topics and gives you something more to think and talk
about at the NAB Convention.  Ask lots of questions and keep
the manufacturers on their toes.  Hope to see you there!

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  FM TRANSLATOR OPERATOR ALLEGEDLY USES UNAUTHORIZED INPUT FEED

  FM translator stations that output in the commercial portion
of the FM band (92.1 - 107.9 MHz) must receive their input
signals over-the-air, directly from the primary station being
translated, or from another FM translator station.  Alternate
feeds such as phone lines, microwave systems and satellite
signals are not allowed (FCC Rule Section 74.1231(b)).

  One translator operator in Southern California was alleged to
be using a satellite feed for a translator that dumped out in
the commercial band - clearly a violation of the Rules.  Marvin
Collins of KFI/KOST/KACE/KRTO did an outstanding detective's job,
and his abridged legal Declaration (the full text of which is
on file with the Commission) is on display at:

  http://www.bext.com/_CGC/k12345.htm 

  While the translator operator denied the charges, his defense
was lame.  The bottom line is that you need to keep an eye out
for similar cases of translator abuse.  If the FCC can't control
translators, can we expect any better results with Low Power FM?

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  SHOULD THE DTV INDUSTRY ABANDON 8-VSB MODULATION?

  There are only two types of modulation used in the traditional
(non-DTV) over-the-air broadcasting industry: AM and FM.
Conventional NTSC television is actually a combination of AM
(for the picture) and FM (for sound).  Attributes of both AM
& FM appear in C-Quam AM stereo, and in over-the-air DTV.

  Over-the-air DTV relies on a modulation scheme called 8-VSB
which some engineers believe was adopted in haste, and which
has (so far) not worked all that well on indoor receiving
antennas.  Some engineers consider the 8-VSB problems so serious
that something must be done now, before over-the-air DTV goes
'the way of AM radio.'

  One recommended solution is to switch to COFDM modulation
which seems to be pretty much immune to multipath and is rapidly
gaining acceptance in other industries.  (For information on the
virtues of OFDM, which is similar to COFDM, see CGC #318, second
story.)

  A writer for Broadcast Engineering magazine shares his
personal views on the 8-VSB problem with us at:

  http://sbe36.org/1999/0410_larry.html 

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                     LETTERS TO THE EDITOR
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  HAM RADIO RECEPTION AT NAB

  Another reason to go...  We've donated about $700 worth
of cool door prizes... maybe you'll win!

  Hank Landsberg, WB6MEU, Henry Engineering

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  THE TRUTH ABOUT Y2K

  http://sos.wustl.edu/mil_bug.gif 

  A cartoon courtesy of Mark van der Hoek

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