THE CGC COMMUNICATOR
                            CGC #914
                    Wednesday, June 17, 2009
                Robert F. Gonsett, W6VR,  Editor
                <cgc (at) cgc333.connectnet.com>
    Copyright 2009, Communications General® Corporation (CGC)
  As it stands now, KUSI will inform its viewers that it
will return to Virtual Channel 51 tonight (Wednesday) at about
11:59 PM.  It will stop using Virtual Channel 18 which it started
using just days ago.  At the same time on Wednesday night,
KDTF-LP will relinquish its use of Virtual Channel 51 and will
move to Virtual Channel 36 according to one report.
  This means that San Diego over-the-air viewers must execute
a rescan Thursday morning if they want to continue receiving KUSI
and/or San Diego's new low power TV station KDTF-LP.
  This also means that if any other San Diego stations want
to tweak their PSIP codes, late Wednesday is the time to do so
-- in advance of the market-wide rescan.
  Now for the technical details for those who are interested.
  In the text that follows, it is important to keep in mind
that each digital TV station has two channel numbers associated
with it.  There is what we will call the Virtual Channel (the
number the viewer sees on the TV screen) and the RF Channel
(the number of the radio frequency channel where the TV
automatically tunes to pick up the incoming digital data --
the TV set is smart enough to know where to look).
  Sometimes different words are used to depict the terms Virtual
Channel and RF Channel as you'll see in the following paragraphs,
but you should be able to figure out what's going with a bit of
  Let's start from the beginning:
  The following story in CGC #912 attracted more than the usual
amount of attention from readers:
  "At the time of the DTV conversion, KUSI-DT in San Diego
changed their PSIP code so receivers would display Channel 18.1
instead of 51.1.  That little change totally confused some sets
& converters to the point where KUSI was no longer decoded, but
that problem was resolved with rescanning.
  "Why did KUSI decide to display its true DTV RF channel (18)
instead of its old analog channel (51)?  Most likely it's because
RF Channel 51 had just become occupied by a new LPTV station.
KDTF-LP is reportedly broadcasting in DTV from San Miguel Mtn.
with Univision on 51.1 and Telefutura on 51.2.  KDTF is operating
under an STA effective 6/11/09:  ERP = 12.4 kW directional,
beaming southwest."
  Immediately after this story was published, CGC Communicator
readers indicated that KUSI could not advertise itself as Virtual
Channel 18 without an FCC Rule waiver, something that KUSI did not
possess.  The bottom line was that KUSI had to call itself Virtual
Channel 51 because it had used Analog Channel 51; the FCC's Rules
require that the Analog Channel number be preserved as we
transition to DTV.
  To make a long story short, KUSI thought it was doing a good
deed by moving to PSIP (Virtual) Channel 18 in recognition of
the fact that an LPTV would be lighting up on 51.  KUSI even had
artwork prepared and planned a large reprinting of stationary
to advertise themselves as "Channels 9/18" (cable Channel 9,
Virtual (over-the-air) Channel 18).
  After seeing the CGC Communicator story and our reader's
letters, and consulting with the FCC, KUSI concluded that a
waiver of the Rules was not in the cards and that the station
must in fact move back to Virtual Channel 51.
  Thanks to CGC Communicator readers for being alert and
catching this problem early, before it became very costly for
KUSI to correct.  Thanks also to KUSI for keeping us informed
of the developments at their end.  This story should have a happy
ending after Thursday's rescan.
  Further information on Virtual and RF Channel numbers is
contained in Annex B of ATSC standard A/65 at the URL below,
although somewhat different vernacular is used:
  CGC is asking its readers to hold Letters to the Editor to
a minimum at this time (and honor our 100 word limit).  Our staff
is stretched thin as we are helping resolve other DTV issues.
  The CGC Communicator is published for broadcast engineering
  professionals in so. California by Communications General®
  Corporation (CGC), consulting radio engineers, Fallbrook, CA.
  Letters to the Editor are always welcome but must be non-
  commercial in nature and kept to 100 words or less.  If you
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  CGC Communicator articles may be reproduced in any form
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  unaltered and credit is given to the CGC Communicator.  Past
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  courtesy of Bext Corporation.
  Typographical errors originating in FCC material are
  reproduced in our newsletter without speculative corrections.
  The views expressed in our newsletters do not necessarily
  reflect those of Communications General® Corporation, Bext,
  or the newsletter editor.
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