DTV, SD, ED, HD, NTSC, ATSC, TMA (was: Voip teleophony)

[Ben Scott]

On 12/13/05, Jeff Kinz <jkinz at kinz.org> wrote:
> Isn't there an intermediate format known as "SD" which is a digital
> broadcast that has the same resolution as an analog broadcast?

  The TV broadcast system the US has been using for decades is NTSC,
which is a fairly ancient, analog standard.  We are in the process of
switching to DTV (digital television), as defined by ATSC.  Currently,
both analog and digital signals are broadcast.  NTSC is supposedly
being phased out, and is scheduled to be terminated Real Soon Now. 
The actual deadline keeps getting pushed back.  Exactly when it will
happen in reality is still unclear, but it appears generally accepted
that it will eventually happen, and within a few years.

  Once the analog NTSC broadcasts cease, you will need a digital tuner
to receive US TV broadcasts.  Newer TVs generally have a digital tuner
built-in.  Alternatively, many cable and satellite services already
require a "set-top box", which generally includes all you need.  If
you want to receive OTA (over the air) DTV broadcasts with an older
TV, you will have to buy an external tuner.

  The digital format enables a number of things, including
compression, non-video data, metadata, and new audio and video
formats.  The last is the important one for most people.  With NTSC,
you only have a single option for picture format.  ATSC defines a
whole slew of picture formats, which are grouped into SD, ED, and HD
-- Standard, Enhanced, and High Definition, in order of increasing
quality.

  Digital does not automatically mean HD.  Indeed, as far as the TV 
signal distribution companies are concerned, one of the benefits of
ATSC is that they compress their existing programming at a ratio of
about 6:1, freeing up valuable bandwidth which can then be sold at a
tidy profit.

mike ledoux <mwl+gnhlug at alumni.unh.edu> writes:
>> Most likely, my replacement for this TiVo will be a nice MythTV box
>> with a couple of HD tuners, but I probably won't bother until SD
>> broadcasts become unavailable.

On 12/13/05, Paul Lussier <p.lussier at comcast.net> wrote:
> Do you mean HD in that last sentence?

  I suspect Mike either means (1) when OTA analog broadcasts cease,
thus requiring an external digital tuner for an analog-only TiVo or
(2) when enough programming has transitioned to ED/HD that upgrading
from an SD-only TiVo becomes worth it.

-- Ben
AAAAAAA: American Association Against Abbreviation And Alliteration Abuse