TV Namespaces
From: Michael A. Dolan (miked@tbt.com)
Date: Tue, Aug 31 1999
Message-Id: <3.0.5.32.19990831080743.00986c60@cts.com>
Date: Tue, 31 Aug 1999 08:07:43 -0700
To: www-tv@w3.org (WWW TV List)
From: "Michael A. Dolan" <miked@tbt.com>
Subject: TV Namespaces
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There are several namespaces in TV. Here's a shot at describing
them. Again, this may have an ATSC slant. If so, then some DVB-
specialist will:
Namespace Authority US Intern'l
- ----------------------------------------------------------
Callsigns ITU Yes Yes
Networks ? Yes No
Channel Names Transport Company No No
Feeds ? No No
Channel # ITU Yes Yes
Callsigns are global names for Broadcasters. The top level authority
is the ITU, with it being managed in the US by the FCC. Everything
that emits TV (as well as other kinds) radio waves has a callsign.
But non-broadcast feeds (HBO) are not part of this namespace since
they do not transmit directly to receivers.
Network names are generally unique within a country but not across
countries. Broadcasters can be either independents, or local
affiliates of a network. So broadcasters generally have a network
affiliation (but it may be null). There is a relationship between
the Channels (names and/or numbers) and Networks.
Channel names are those names that appear in EPG's. These names may
be callsigns, network names, feed names and/or channel numbers. They
are assigned by the transport company carrying the guide, and are
unique only within that transport company.
Feeds are non-broadcast programs that have names (HBO, HBOW, etc.)
However, the Channel that is called HBO in one Transport may well not
be the same Content as the Channel that is called HBO in some other
Transport. HBO has multiple feeds that the Transport Companies may
or may not choose to carry.
Channel #'s are not unique globally without more information.
However, they are in a well-managed namespace. A channel # is unique
given its ITU Region (in the case of a Broadcaster), or its Transport
(given cable and satellite). For example, channel 7 in US/ITU Region
5 is globally unique and equal to KABC (Los Angeles). There is a one-
to-one relationship between Broadcasters and (in the case of ATSC,
major) channels. Note also that ATSC channels have 2 numbers and are
of the form <major>.<minor>. A Broadcaster owns the major number and
then can broadcast multiple minor (digital) channels.
For the curious, the US Region map is here:
http://www.fcc.gov/wtb/publicsafety/images/ps55rgns.gif
Within these areas (and immediately adjacent areas), there is no
duplication of channel numbers. Since in NTSC analog, channel ==
frequency.
Mike
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Michael A. Dolan, Representing DIRECTV, (619)445-9070
PO Box 1673 Alpine, CA 91903 FAX: (619)445-6122