How many Digital Subchannels

Mark Casey
Mon Aug 15 13:39:17 EDT 2011

Believe Wikipedia, or not,
but there's a neat chart in the "digital subchannel" listing that shows 
sub-channel possibilities.
The fly in the ointment is the fact that some broadcasters may be using 
different resolutions than in the chart, and /or different than are listed 
in the A53 or A72 chart at "ATSC standards". A good example is channel 3, 
Hartford's  (rf ch.33) channel 3-4. It's advertised as "Channel 3 Fairfield 
County", but is a much lower than 480 resolution. It's horrible on a regular 
digital or converted TV. Maybe they are experimenting with it for Mobile TV 
use. I talked with a knowledgeable CE of another local station, a 
competitor, and he was wondering what they were doing with it.
Is any station in the Boston market doing the low-resolution thing?
The most I've seen is 1 HD plus 3 SD, but I can imagine if the resolutions 
for both are adjusted to, the absolute minimum for HD and, the "SD" 
resolution is cut down, the 1HD+4SD scenario might be possible.
As far as former channel displays go, my older boxes & tv's seem to retain 
all the channels after rescan (but I haven't tried the unplug-recan w/no 
antenna procedure), while many of the newer boxes & tv's wipe out all the 
old info after every rescan.

Mark Casey
Hampden, MA

----- Original Message ----- 
From: "Dan.Strassberg" <>
To: "Garrett Wollman" <>; "A Joseph Ross" 
Cc: "Boston Radio" <>
Sent: Monday, August 15, 2011 9:11 AM
Subject: Re: Channel 44

On my 27" DTV receiver, 44-1 was, for a few weeks, duplicated on 44-5.
(I point out the screen size because the receiver does not do 1080P;
it does, however, do--or claim to do--1080I). During the brief period
when programs appeared on 44-5, 44-5 was apparently in HD (alleged, on
the receiver's "info" screen to be 1080 lines), whereas 44-1 appeared
to be in standard definition (the receiver appears to call that 480

In order to get the receiver to display 44-5, I first had to
have it "rescan" the channels. A week or two ago, 44-5 went dark and
remains so. Although I can select 44-5, when I do, the screen goes
black. I don't recall whether the "program not available" message
appears. Simultaneously with 44-5 going dark, 44-1 now displays on the
info screen as being 1080 lines. It does indeed appear to be in the
9x16 aspect ratio. So I believe that 44-1 has now converted to HD and
44-5 has disappared (but it has left a trace of itself--dead channels
seem to leave traces of themselves; despite many "rescans," what I
believe to be the VHF versions of 7-1 and 7-2 continue to appear even
though the UHF versions are enabled and are the only 7s that provide
programming; the VHF 7s produce only black screens).

I don't understand how 44 could have transmitted four SD
streams plus one HD stream in one 6-MHz channel. My understanding was
that one channel could support four SD streams or one HD stream and
one SD stream. As far as I can tell, Channel 2 transmits one HD stream
and one SD stream although 2 also displays two additional subchannels
numbered (IIRC) 104 and 105. These two have been black since I first
got the DTV receiver two years ago.

I find this whole business very confusing and I wish somebody would
explain it to me. Clearly it was not intended to be understood by the
general public. Even having two degrees in electrical engineering does
not provide me with the background to figure out what is going on.

Dan Strassberg (
eFax 1-707-215-6367

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