[opendtv] Re: --FCC OKs WiFi between TV channels
- From: "John Willkie" <jmwillkie@xxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 28 May 2004 11:03:52 -0700
And, I doubt that a 4:3 set of less than 50 inches in horizontal screen size
would offer the display "resolution" that you speak of in #2. Should I do
the math on dot pitch for you? Again?
You seem to get hung up on display aspect ratio and sample aspect ratio, at
least when you assert the ar of 1024 x whatever sets. In my world, these
are 4:3 sets, not 1:2.35.
John Willkie
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx
[mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Craig Birkmaier
Sent: Friday, May 28, 2004 7:30 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: --FCC OKs WiFi between TV channels
At 11:18 PM -0700 5/27/04, John Willkie wrote:
>So, then what makes an HDTV set? Would an analog 4:3 set qualify?
Good question.
1. From the ATSC perspective it must display all ATSC formats.
2. From the CEA perspective it must offer at least 1280 x 720
resolution (but it does not need to actually reproduce all of the
source resolution).
3. From a purist perspective it must provide a sharp image over a 30
degree field of view at 3.3 picture heights.
Clearly a 4:3 NTSC display does not have the ability to do any of these
things.
A 4:3 EDTV display (up to 540P resolution) can handle #1, but not #2 or #3.
A 4:3 projector using the TI 1280 x 1024 chips can satisfy all three.
Virtually all CRT based HD displays fall short of #3, and they cheat
on #2. Any direct view HD CRT display will fall far short of the goal
in horizontal resolution since the shadow masks have no more than 850
samples in the horizontal. Any consumer CRT based RPTV will also fall
far short in the horizontal because of the limitations of the amps
and the CRTs themselves; these displays typically have the ability to
resolve no more than 850-1000 samples per line.
The reality is that hardly anyone has an HD display that can deliver
on #3, which is the basic criteria for the HDTV viewing experience.
Regards
Craig
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