Question on Tuners

Archived from groups: alt.tv.tech.hdtv (More info?)

In article <7vtji19urpceapg79v22jskbc8l7f92plc@4ax.com>,
JoAnne <mwsoft@cox.net> wrote:

> Is an ATSC tuner the same as an HDTV tuner?
>
> If "Yes," than one or the other will receive OTA HD?
>
> Is an NTSC tuner only good for analog TV reception?
>
> What is the bandwidth of an analog tuner versus an HDTV tuner?

yes
yes
yes
non-sequitur

Archived from groups: alt.tv.tech.hdtv (More info?)

Matthew L. Martin wrote:
> JoAnne wrote:
>
>> Thursday, September 15 2005, @ 3:38 PM (-0700 GMT)
>>
>> Gentlemen:
>>
>> Is an ATSC tuner the same as an HDTV tuner?
>
>
> It is an HDTV tuner and more, as it also decodes signals that are less
> than HDTV in quality.
>
>> If "Yes," than one or the other will receive OTA HD?
>
>
> From that point of view, they are identical.
>
>> Is an NTSC tuner only good for analog TV reception?
>
>
> Yes.
>
>> What is the bandwidth of an analog tuner versus an HDTV tuner?
>
>
> Hmmmm ... That question isn't well formed. Here are A couple of data
> points.
>
> 1) NTSC and ATSC signals consume the same amount of bandwidth.
>
> b) ATSC can deliver a signal that, when decoded, has ~5 times the
> resolution of an NTSC signal and a much broader color gamut.
>
>> Thank you,
>
>
> I hope that helped.
>
> Matthew
>
Hi,
In analog TV format, video is AM, audio is FM. I think channel spacing
is 6 MHz. Actual b/w being something like 4.5MHz(video + audio). I guess
HD format has to carry on in this channel spacing scheme
I could be wrong. My memory is no good any more, LOL.
Any how, you got the idea.
Tony

Archived from groups: alt.tv.tech.hdtv (More info?)

--
www.unclet.netfirms.com
"Jeff Rife" <wevsr@nabs.net> wrote in message
news:MPG.1d93e2cd7b64f70b989fb9@news.nabs.net...
> JoAnne (mwsoft@cox.net) wrote in alt.tv.tech.hdtv:
>> Is an ATSC tuner the same as an HDTV tuner?
>
> In the US and Korea, yes. In countries like Japan and Australia, no.
> Those countries use a different system for digital OTA TV.
>
> In addition, there are digital cable tuners for the US, and those can
> decode HD over cable, so they are "HDTV tuners". In the US, there aren't
> any "end user purchase" digital cable tuners that don't also handle OTA
> digital reception. The digital cable box that the cable company gives you
> might handle HD, but it won't handle OTA digital in any way.
>
> --
> Jeff Rife |
> | Visualize Whirled Peas

Can we say "too much information?"

Archived from groups: alt.tv.tech.hdtv (More info?)

"JoAnne" <mwsoft@cox.net> wrote in message
news:7vtji19urpceapg79v22jskbc8l7f92plc@4ax.com...
> Thursday, September 15 2005, @ 3:38 PM (-0700 GMT)
>
> Gentlemen:
>
> Is an ATSC tuner the same as an HDTV tuner?
>
> If "Yes," than one or the other will receive OTA HD?
>
> Is an NTSC tuner only good for analog TV reception?
>
> What is the bandwidth of an analog tuner versus an HDTV tuner?
>
> Thank you,
>
> JoAnne
> WebMistress: http://www.AntiVirusYellowPages.com/
>

ATSC is a digital tuner and it is needed to receive HD OTA. There are 18
standards of which 480p, 720p and 1080I are the most common HD modes. An
NTSC tuner is the old analog tuner due to be phased out in 2008 for OTA
broadcasts.

Archived from groups: alt.tv.tech.hdtv (More info?)

--
www.unclet.netfirms.com
"Jeff Rife" <wevsr@nabs.net> wrote in message
news:MPG.1d941520ae7e5df3989fba@news.nabs.net...
> Guest (n0gar@hotmail.com) wrote in alt.tv.tech.hdtv:
>> Can we say "too much information?"
>
> Can we say "don't post everything beneath your sig block delimiter, and
> remove other sig blocks when you post?
>
> Other than that, since we don't know exactly where the poster is from,
> nor do we know whether they want HD over cable and think an ATSC tuner
> will get it for them (this was the FCC's original thought of how digital
> cable would likely work, so it's not an outlandish thought), no, it wasn't
> too much information.

Well since he asked about ATSC and NTSC, we can assume that he is not from
Germany. North America and the US is more likely. Then again, you are
right, we should not assume. However, given what he is asking specifically,
one must assume.

>
> --
> Jeff Rife | "Damn it, I miss the sound of her voice. I tried
> | putting silverware down the disposal, but it
> | wasn't the same."
> |
> | -- Ned Dorsey, "Ned and Stacey"

Archived from groups: alt.tv.tech.hdtv (More info?)

On Fri, 16 Sep 2005 00:25:14 GMT Tony Hwang <dragon40@shaw.ca> wrote:

| In analog TV format, video is AM, audio is FM. I think channel spacing
| is 6 MHz. Actual b/w being something like 4.5MHz(video + audio). I guess
| HD format has to carry on in this channel spacing scheme
| I could be wrong. My memory is no good any more, LOL.
| Any how, you got the idea.
| Tony

Within the 6 MHz channel, the main video carrier is +1.25 MHz from the
lower end of the channel, maybe plus or minus 10 kHz in certain cases.
The modulation of this carrier is vestigial sideband, which in simple
terms means some of the information is carried in both sides of the
video carrier, and the rest is carried only above the video carrier.
The color carrier is 315/88 MHz (roughly 3.579545 MHz) above the video
carrier, which ends up there because that difference is the frequency
of the color subcarrier in source baseband video. That carrier is
quadrature modulated with two color difference signals of reduced
bandwidth, per the NTSC specifications. The audio carrier is 4.5 MHz
above the video carrier and is frequency modulated with a deviation of
45 kHz (less than the 75 kHz used in FM broadcast on 88-108 MHz).

All of that structure is gone in digital TV. The specific points in
the channel for analog no longer matter for digital. The raw data is
processed by a number of steps to create an 8 level waveform that is
then modulated by a form of vestigial sideband more radical than what
was used for analog. This mostly single sideband modulation product
is confined to the middle 5.38 MHz of the 6 Mhz channel, measured at
the 3db point in filtering. A pilot carrier is than inserted with a
level 11.3 db below the average information power level (plenty enough
to be easily extracted with a narry filter at the expected location).

Digital far more evenly distributes the real information all over the
channel space, than analog does. Analog has major peaks of power in
the channel space (especially at the carriers). This is one of the
reasons digital can go further with less power.

The data stream carries audio and video in compressed form, along with
some additional data, using the ATSC standard. The exact bit rate of
the data stream is 867996/44759 MHz. If you try to carry out that long
division to its extreme, the fractional part will repeat in 312 digits.
By contrast, NTSC's color subcarrier is 315/88 MHz, which only has 2
digits doing the repeating.

They chose to keep the 6 MHz channeling that was already established.
They could have gone with a somewhat smaller channel space, such as
maybe 5 MHz, as that would probably still have been adequate for high
definition (but probably without an extra subchannel along with it).
But changing the channel scheme to 5 MHz would have been a huge nightmare
to manage the transition, with not all that much of an advantage to be
gained in the end. The ATSC transport stream can carry more than one
subchannel of programming, so if it is not all taken up with a maximum
quality high definition program, extra subchannel space is available
all packaged in that 6 MHz of RF spectrum channel space.

More details:
http://www.atsc.org/standards/a_53c_amend-1_corr-1.pdf

Supplementary info:
http://www.atsc.org/standards/a_54a.pdf

--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
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Archived from groups: alt.tv.tech.hdtv (More info?)

JoAnne (mwsoft@cox.net) wrote in alt.tv.tech.hdtv:
> My reason for asking about "bandwidth" was because, I would think that
> you usually do not get "something for nothing," and if an HDTV station
> transmits an image with MUCH more "quality," (content), than an analog
> signal, wouldn't the HDTV signal occupy more "space" and maybe even
> take more "power" to send?

The digital signal is compressed heavily using MPEG-2. It still looks very,
very good because MPEG-2 can do that, but that's one reason so much "extra"
can be fit into the same frequency band.

Another reason is that the digital signal uses tricks with the phase of the
signal to encode more data per unit time than a plain analog signal can
handle.

--
Jeff Rife | "If we give peas a chance, won't the lima
| beans feel left out?"
|
| -- Pinky

Archived from groups: alt.tv.tech.hdtv (More info?)

"JoAnne" <mwsoft@cox.net> wrote in message
news:tunli1593q6b3kj629u8gfks0jbdbql3rf@4ax.com...
> Friday, September 16 2005, @ 8:08 AM (-0700 GMT)
> ...................................
>I guess they must be
> picking up the OTA signal on Channel 60 and then sending it to me on
> "Channel 702?" This seems to make sense, i hope! <g>
>
> Many thank yous!
>
> JoAnne
> WebMistress: http://www.MicrowaveSoftware.com/


Actually I wouldn't bet on it. Comcast here seems to be getting a direct
studio feed from the local stations via microwave or fiber. I know this to
be the case, because cable works normally even when a transmitter is down.

Tam
>
> (and other sites <g> )
>
>
>
> On Thu, 15 Sep 2005 15:43:17 -0700, JoAnne <mwsoft@cox.net> wrote:
>
>>Thursday, September 15 2005, @ 3:38 PM (-0700 GMT)
>>
>>Gentlemen:
>>
>>Is an ATSC tuner the same as an HDTV tuner?
>>
>>If "Yes," than one or the other will receive OTA HD?
>>
>>Is an NTSC tuner only good for analog TV reception?
>>
>>What is the bandwidth of an analog tuner versus an HDTV tuner?
>>
>>Thank you,
>>
>>JoAnne
>>WebMistress: http://www.AntiVirusYellowPages.com/
>
>
>

Archived from groups: alt.tv.tech.hdtv (More info?)

Tam/WB2TT wrote:

>For OTA the analog and HDTV channels are both 6 MHz wide. On a good day, the
>B/W analog video bandwidth is about 4.2 MHz. An ATSC tuner is digital, and
>receives digital data at about 19.4 Megabits/second; this can consist of one
>1080i channel, or several lower resolution channels.

I don't understand what the local channel is doing; it consists of
three OTA signals on analog 11 and digital 12:

tuner 11-0: analog 11
tuner 11-1: digital 12 SD
tuner 11-2: digital 12 HD (1080i)

Are you saying that there is only enough bandwidth for one channel on
12 if HD 1080i is broadcast? Then how are they broadcasting SD too?
Do you think maybe the HD 1080i signal on 11-2 is compressed to make
enough room for SD on 11-1?

Archived from groups: alt.tv.tech.hdtv (More info?)

On Fri, 16 Sep 2005 12:53:39 -0400 Matthew L. Martin <nothere@notnow.never> wrote:

| phil-news-nospam@ipal.net wrote:
|
| verbal diarrhea snipped.
|
| That information helps the original poster,how?

It further clarifies what Tony posted, providing a condensed form of
explanation of what is going on in the channels. It's to help other
readers, including newbies, as much as for the original poster.

Helping people by actually providing some information is a concept
quite foreign to you and your twin. I'm sure the two of you would
prefer to just say "do your research".


| Moron.

Matthew L. Martin <nothere@notnow.never> will find any and all excuses
to avoid a technical discussion based on the facts, merit, logic,
and/or analysis of the topic at hand, preferring instead to twist or
selectively interpret what people say in order to find a means to make
personal attacks, or incite flame wars. If you catch him doing this,
you can help others by posting a followup that points out the errors
in his postings. There might be hope in salvaging what could otherwise
be a smart person.

--
-----------------------------------------------------------------------------
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
-----------------------------------------------------------------------------

Archived from groups: alt.tv.tech.hdtv (More info?)

Jeff Rife wrote:

>If the SD sub-channel is the same programming as the HD channel but just
>not in HD, it's a waste, since unlike other countries, every digital TV
>receiver in the US can decode HD.

Yes, but the station can't turn off the SD sub-channel until they
resolve issues with captioning and feeds to cable & dish providers.