[opendtv] Re: Digital vs. Analog Quality

  • From: "Dale Kelly" <dalekelly@xxxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Tue, 15 Jul 2008 09:59:41 -0700

Cliff wrote:
> As for wide Y and C bandwidth sets being 50 years too late I think that
> any such TVs from the '50s through the early '70s would probably not
> have improved the resolution of the images at home.
>
> It was the act of decimating the RGB signal with an NTSC broadcast
> encoder that for most sets, limited it's resolution to ~40 lines for C
> and ~320 for Y.

NTSC encoder design improved significantly from the mid 70s on. The limiting
factor was then the design of TV receivers color circuitry, which didn't
improve until, as you report, DTV ready sets were introduced about five
years ago.

However, we've gotten off track; your original observation was that TV sets
connected to converter boxes would receive an improved color signal and my
reply was that no one would see it due to the color band pass limits built
into the users TV sets. However, given that the new DTV ready sets might
have improved color performance, I will change my prediction - about 99
percent of home viewers will not see that improvement.

Dale

> -----Original Message-----
> From: opendtv-bounce@xxxxxxxxxxxxx
> [mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Cliff Benham
> Sent: Sunday, July 13, 2008 6:58 PM
> To: opendtv@xxxxxxxxxxxxx
> Subject: [opendtv] Re: Digital vs. Analog Quality
>
>
> Dale Kelly wrote:
> > Can I assume that all DTV sets with NTSC tuners now have full
> NTSC chroma
> > bandwidth? If so, that's only about 50 years too late.....
>
> It's a hard question to answer since all the new sets and displays with
>   NTSC composite and S-video inputs don't bother to say what their
> chroma bandwidths are in the specs I've downloaded.
>
> I think you will have to check them out one by one with good test gear
> to know for certain.
>
> As for wide Y and C bandwidth sets being 50 years too late I think that
> any such TVs from the '50s through the early '70s would probably not
> have improved the resolution of the images at home.
>
> It was the act of decimating the RGB signal with an NTSC broadcast
> encoder that for most sets, limited it's resolution to ~40 lines for C
> and ~320 for Y.
>
> In the late 1940s there were several proposals before the FCC to
> transmit color only in the new UHF band with channel bandwidths of from
> 12 to 18 megacycles (!) None were ever approved for commercial use.
>
> Broadcast NTSC was the sole signal source of programming during those
> decades, and even if your set was a Conrac or RCA studio monitor, you
> would not have seen much improvement in either Y or C resolution.
>
> It's only since the advent of Laserdisks, S-video, DVDs and digital TV
> receivers that it's possible to watch higher chroma resolution images.
>
> It's also hard to know if the new sets are using good I&Q decoders,
> wideband R-Y&B-Y decoders or ??? for NTSC because the manufacturers
> don't include such information in their specs.
>
> I guess they want to emphasize only the 'digital' aspects of their new
> products or perhaps at least widen the percieved quality differences
> between the analog and digital images.
>
>
>
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