Do I have a proper understanding of HDTV?

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

This is my understanding; please correct me if I'm wrong:

Digital TV takes 1/4 as much bandwidth as analog TV to give the same quality
of picture. i.e. 1.5Mhz will suffice for a picture that would take the full
6Mhz channel to deliver in analog form. This 6Mhz channel can thus be used
to deliver 4 different programs, or a single program having twice the
resolution--HDTV. Presumably, each TV station will be free to use its 6Mhz
in whichever way it wishes.

DTV signals are broadcast on entirely different frequencies than the current
analog signals, so the 2 can co-exist as long as the government sees fit to
allow it.

There will be a standard set of frequency allocations that will be used by
all cable systems, making it possible to manufacture digital TV sets with
universal tuners, much as current sets have standard CATV tuners.

Thank you,

Norm Strong

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

On Tue, 26 Apr 2005 08:58:00 -0700, normanstrong@comcast.net wrote:

> This is my understanding; please correct me if I'm wrong:
>
> Digital TV takes 1/4 as much bandwidth as analog TV to give the same quality
> of picture. i.e. 1.5Mhz will suffice for a picture that would take the full
> 6Mhz channel to deliver in analog form. This 6Mhz channel can thus be used
> to deliver 4 different programs, or a single program having twice the
> resolution--HDTV. Presumably, each TV station will be free to use its 6Mhz
> in whichever way it wishes.

Correct. There are 18 different ATSC formats, and some of them use less
than the full 6MHz, so more than one at a time can be broadcast in some
cases.

>
> DTV signals are broadcast on entirely different frequencies than the current
> analog signals, so the 2 can co-exist as long as the government sees fit to
> allow it.

Sort of. The channels haven't changed, there are still 2-13 VHF (54-216MHz
with some gaps) and 14-69 (470-806MHz). The digital broadcasts can co-exist
with analog because they are on other channels (usually UHF). The box can
make it look like any channel they want ("digital 4").

>
> There will be a standard set of frequency allocations that will be used by
> all cable systems, making it possible to manufacture digital TV sets with
> universal tuners, much as current sets have standard CATV tuners.

Digital TV on cable systems uses a different scheme for carrying HDTV. The
Digital TV's will need multi-function tuners, there won't be a standard
method of receiving both. What is coming is smart cards that you can put
into your TV so it can decode scrambled content. Of course, the smart card
will come from your cable company so they can bill you for its use.

Brad Houser

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

<normanstrong@comcast.net> wrote in message
newsZydnYJ0XqmV-PPfRVn-3w@comcast.com...
> This is my understanding; please correct me if I'm wrong:
>
> Digital TV takes 1/4 as much bandwidth as analog TV to give the same quality
> of picture. i.e. 1.5Mhz will suffice for a picture that would take the full
> 6Mhz channel to deliver in analog form. This 6Mhz channel can thus be used
> to deliver 4 different programs, or a single program having twice the
> resolution--HDTV.

More than twice the resolution. If we take DVD resolution (better than pretty
much any analog source for SD television) as the resolution of analog TV, we
get 720x(480/2) = 172,800 pixels per field. In contrast, 720p HDTV is
1280x720 = 921,600 pixels per field, or 1080i is 1920x(1080/2) = 1,036,800.

That's more than 5 times the resolution of the analog signal, not to mention
the image is noise free, and digital (often surround) sound comes along for
the ride.

Ken

 

[Sean]

Archived from groups: alt.video.ptv.tivo (More info?)

On Tue, 26 Apr 2005 08:58:00 -0700, <normanstrong@comcast.net> wrote:

>This is my understanding; please correct me if I'm wrong:
>
>Digital TV takes 1/4 as much bandwidth as analog TV to give the same quality
>of picture. i.e. 1.5Mhz will suffice for a picture that would take the full
>6Mhz channel to deliver in analog form. This 6Mhz channel can thus be used
>to deliver 4 different programs, or a single program having twice the
>resolution--HDTV. Presumably, each TV station will be free to use its 6Mhz
>in whichever way it wishes.
>
>DTV signals are broadcast on entirely different frequencies than the current
>analog signals, so the 2 can co-exist as long as the government sees fit to
>allow it.
>
>There will be a standard set of frequency allocations that will be used by
>all cable systems, making it possible to manufacture digital TV sets with
>universal tuners, much as current sets have standard CATV tuners.
>
>Thank you,
>
>Norm Strong
>

You should apply for a job with Tivo.

They haven't been able to figure this out for years. The only Tivo
that can do HD was produced by DTV and they're dumping that for an
improved model soon.

Sean

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

I believe you have a misunderstanding of the difference between
"digital TV" and HDTV, judging from your header and opening paragraph.

This is very similar to the misunderstanding most people have of "high
fidelity" and "stereo" re the AM Stereo debacle (where "stereo" was
thought to mean "high Fidelity" and everyone was disappointed because
the receiver manufactureres made low fi stereo AM receivers- thanks
again, Motorola! You just never learn.. judging from your cable boxes!


On Tue, 26 Apr 2005 08:58:00 -0700, <normanstrong@comcast.net> wrote:

>This is my understanding; please correct me if I'm wrong:
>
>Digital TV takes 1/4 as much bandwidth as analog TV to give the same quality
>of picture. i.e. 1.5Mhz will suffice for a picture that would take the full
>6Mhz channel to deliver in analog form. This 6Mhz channel can thus be used
>to deliver 4 different programs, or a single program having twice the
>resolution--HDTV. Presumably, each TV station will be free to use its 6Mhz
>in whichever way it wishes.
>
>DTV signals are broadcast on entirely different frequencies than the current
>analog signals, so the 2 can co-exist as long as the government sees fit to
>allow it.
>
>There will be a standard set of frequency allocations that will be used by
>all cable systems, making it possible to manufacture digital TV sets with
>universal tuners, much as current sets have standard CATV tuners.
>
>Thank you,
>
>Norm Strong
>

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

normanstrong@comcast.net wrote:

> DTV signals are broadcast on entirely different frequencies than the current
> analog signals

False. They are broadcast on exactly the same frequencies
as analog channels. For instance, in San Jose, NBC in NTSC is on
channel 11 and NBC on ATSC is on channel 12. Channel 48 is analog
and channels 49, 50, 51, and 52 are digital; digital receivers
don't have the problem of adjacent-channel interference like analog
tuners.
-Joe

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

normanstrong@comcast.net wrote:

> There will be a standard set of frequency allocations that will be used by
> all cable systems, making it possible to manufacture digital TV sets with
> universal tuners, much as current sets have standard CATV tuners.

Yes, devices with CableCard compatible tuners can receive digital
signals via cable TV. No, the digital signals will not be restricted
to a small subset of frequency allocations.

Have you seen the HDTV FAQ on the TiVo Community Forums?
http/www.tivocommunity.com/tivo-vb/showthread.php?t=151443

-Joe

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

"Joe Smith" <joe@inwap.com> wrote in message news:--Odncstjv8ad-3fRVn-jA@comcast.com...
> normanstrong@comcast.net wrote:
>
> > DTV signals are broadcast on entirely different frequencies than the current
> > analog signals
>
> False. They are broadcast on exactly the same frequencies
> as analog channels. For instance, in San Jose, NBC in NTSC is on
> channel 11 and NBC on ATSC is on channel 12. Channel 48 is analog
> and channels 49, 50, 51, and 52 are digital; digital receivers
> don't have the problem of adjacent-channel interference like analog
> tuners.

According to the FCC website, the KNTV frequency assignments for
analog broadcasting is 198-204 MHz and digital broadcasting is assigned
204-210 MHz. Those frequency ranges are different. If the frequencies
were the same viewers would not be able to receive either digital or analog
transmissions.

Digital television uses the same 6 MHz bandwidth as an analog broadcast.

In the San Francisco bay area channels 4 and 5 are adjacent and neither
suffers interference from the other channel. People living in the (deep) south
bay can receive channels 7,8 and 9 without interference from the adjacent
channel. Folks living midway between Oakland and Sacramento can view channels
2 and 3 without problems.

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

In article <akace.2413$zu.54@newssvr13.news.prodigy.com>, Jack Ak
<akjack@excite.com> wrote:

> In the San Francisco bay area channels 4 and 5 are adjacent and neither
> suffers interference from the other channel.

The same holds true in New York.

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

"Jack Ak" <akjack@excite.com> wrote in message
news:akace.2413$zu.54@newssvr13.news.prodigy.com...
>
> According to the FCC website, the KNTV frequency assignments for
> analog broadcasting is 198-204 MHz and digital broadcasting is assigned
> 204-210 MHz. Those frequency ranges are different. If the frequencies
> were the same viewers would not be able to receive either digital or analog
> transmissions.

You're both right...kind of. Digital channels use the same set of channels as
analog channels, but they do not run an analog station and a digital station
on the same channel.

That is, if you ignore channel mapping done by some digital TV receivers, an
analog "channel 6" is exactly the same broadcast freuqency as a digital
"channel 6" (assuming it really is channel 6, and not, say, channel 48 mapped
to 6 by the receiver).

At the current time, all the locals have two distinct channels - WFOO and
WFOO-DT. Though the channel numbers are different, the channels they have to
choose from are the same. Eventually (the FCC hopes), the non-DT stations
will go away and the FCC will be able to reuse that chunk of the spectrum.

> In the San Francisco bay area channels 4 and 5 are adjacent and neither
> suffers interference from the other channel. People living in the (deep)
> south
> bay can receive channels 7,8 and 9 without interference from the adjacent
> channel. Folks living midway between Oakland and Sacramento can view
> channels
> 2 and 3 without problems.

The FCC allows for a station brodcasting on channel 5 to interfere with 4 and
6 within a certain geographical area. That doesn't mean that it has to
interfere with adjascent channels. Transmitter technology has improved
greatly since the rules were made, and many transmitters today don't interfere
(or interfere much less) like their predecessors did.

Ken

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

In part, Jack Ak wrote:

> In the San Francisco bay area channels 4 and 5 are adjacent
> and neither suffers interference from the other channel.

Unlike other consecutively numbered channel pairs, the frequencies
assigned to channels 4 and 5 (in this country) are not directly
adjacent to one another. (There's a 4 MHz gap.) That's why the two
channels are permitted to co-exist within markets.


> People living in the (deep) south bay can receive channels
> 7,8 and 9 without interference from the adjacent channel.
> Folks living midway between Oakland and Sacramento can
> view channels 2 and 3 without problems.

Here in New Jersey, we receive New York City and Philadelphia market
stations (including channels 2, 3, 4, 5, 6, 7, 9, 10, 11, 12 and 13)
in the same manner. Television signals traveling from different
directions (and converging at a point in between) generally do not
generate significant interference.

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

David Levy <d_levy@lifeisunfair.net> wrote:
> Here in New Jersey, we receive New York City and Philadelphia market
> stations (including channels 2, 3, 4, 5, 6, 7, 9, 10, 11, 12 and 13)
> in the same manner. Television signals traveling from different
> directions (and converging at a point in between) generally do not
> generate significant interference.

On top of a mountain in Northern California, we used a manual rotator. I'd
go outside and twist the mast while my wife watched the TV.
We received more than one of some channels with no noticeable interference,
and at least one of everything 2-13, except 12, IIRC.
Of course none of it came in very well...

--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5

 

[Guest]

Archived from groups: alt.video.ptv.tivo (More info?)

Jack Ak wrote:
> "Joe Smith" <joe@inwap.com> wrote in message news:--Odncstjv8ad-3fRVn-jA@comcast.com...
>
>>normanstrong@comcast.net wrote:
>>
>>
>>>DTV signals are broadcast on entirely different frequencies than the current
>>>analog signals
>>
>>False. They are broadcast on exactly the same frequencies
>>as analog channels. For instance, in San Jose, NBC in NTSC is on
>>channel 11 and NBC on ATSC is on channel 12.
>
> According to the FCC website, the KNTV frequency assignments for
> analog broadcasting is 198-204 MHz and digital broadcasting is assigned
> 204-210 MHz. Those frequency ranges are different.

Analog channel 11 is 198-204 MHz.
Digital channel 11 is 198-204 MHz.
Both are the exact same frequency range that defines VHF channel 11.

Digital channel 12 is 204-210 MHz.
Analog channel 12 is 204-210 MHz.
Both are the exact same frequency range that defines VHF channel 12.

That's what I meant when stating that digital does not use "entirely
different frequencies". They use the same VHF and UHF bands.

I'm sorry if you thought I was implying two different broadcasts
on the same channels simultaneously. I wasn't.
-Joe

 

[Richard]

Archived from groups: alt.video.ptv.tivo (More info?)

Channels 4 and 5 are not adjacent in frequency. There is a 4 Mhz gap
that separates the two, which is why you can use both channels 4 and 5
in a single region.

"Modern" analog receivers should have no trouble with adjacent channels
in most situations, but older TVs did not have such sharp passbands, so
channels were allocated to prevent adjacent channel interference. Where
I grew up, channel 5 was a distant station and channel 6 was local, so
if you wanted to receive channel 5 you needed to add a "channel 6 trap"
to the antenna feed to help the TV ignore the strong adjacent channel.
This isn't necessary with newer TVs (most TVs built in the last 20 years
or so).

- Richard


Dr. Personality wrote:
> In article <akace.2413$zu.54@newssvr13.news.prodigy.com>, Jack Ak
> <akjack@excite.com> wrote:
>
>
>>In the San Francisco bay area channels 4 and 5 are adjacent and neither
>>suffers interference from the other channel.
>
>
> The same holds true in New York.