RF signal strength
 

I understand HDTV brodcasts will use the UHF channels. I can pick up analog
ones from clear to mild snow. How poor of signal until digital drops out?
Is it true, the low and hi band VHF gets turned over to police and fire? No
more bulky antenna!

When tuning an analog TV to digital frequency, shouldn't I hear or see
something different other than the regular back ground noise? I tried all
channels without analog brodcasts and they are plain noise and snow. I know
the PBS station is digital around here.

Any good website with technical details?
Thanks

RF signal strength
 

"JohnR66" wrote:
I understand HDTV brodcasts will use the UHF channels. I can pick up
analog ones from clear to mild snow. How poor of signal until digital
drops out? Is it true, the low and hi band VHF gets turned over to police
and fire? No more bulky antenna!

When tuning an analog TV to digital frequency, shouldn't I hear or see
something different other than the regular back ground noise? I tried all
channels without analog brodcasts and they are plain noise and snow. I
know the PBS station is digital around here.

Any good website with technical details?
Thanks

Not all digital broadcasts will be UHF.
Not all digital broadcasts will be high definition.
If you are getting a good analog signal,
you will likely get a good digital signal.

Chip

--
-------------------- http://NewsReader.Com/ --------------------
Usenet Newsgroup Service $9.95/Month 30GB

RF signal strength
 

Digital signal loss is definately different than analog signal loss. With
anolog, which many of us grew up with, weak signal meant noisy snowy video
and crackly audio.
Digital is totally different, when the signal level drops to a specific
amount first the picture may freeze or pixalete (Small mosiac like
boxes)and eventually, as the signal level drops, the picture and audio will
just cease. Leaving you with a black or grey screen. Good quality signals
levels are mandated for good digital television reproduction. Any user of
digital satellite systems, AKA Dish, Echostar, Drirect-TV, etc knows waht
"Rain Fade" means.
www.antenna.org may give you a general ides where the broadcasters are
located with respect to your specific location.
Searching the web (Google, Yahoo, Ramp-up, etc) will let you know which
broadcasters are already totally producing digtal signals and which ones
are broadcasting in HD. Then you have a choice of what type of OTA
antennea equiptment to invest in, or just to subscribe to cable or
sattelite.
"JohnR66" wrote in message
...
I understand HDTV brodcasts will use the UHF channels. I can pick up analog
ones from clear to mild snow. How poor of signal until digital drops out?
Is it true, the low and hi band VHF gets turned over to police and fire?
No more bulky antenna!

When tuning an analog TV to digital frequency, shouldn't I hear or see
something different other than the regular back ground noise? I tried all
channels without analog brodcasts and they are plain noise and snow. I
know the PBS station is digital around here.

Any good website with technical details?
Thanks

RF signal strength
 

JohnR66 wrote:
I understand HDTV brodcasts will use the UHF channels. I can pick up analog
ones from clear to mild snow. How poor of signal until digital drops out?
Is it true, the low and hi band VHF gets turned over to police and fire? No
more bulky antenna!

When tuning an analog TV to digital frequency, shouldn't I hear or see
something different other than the regular back ground noise? I tried all
channels without analog brodcasts and they are plain noise and snow. I know
the PBS station is digital around here.

Any good website with technical details?
Thanks

Your information is incorrect. Low and hi band VHF remain for TV,
although low VHF 2 to 6 will not have many stations on it. It is the UHF
52 to 69 frequency space that is being taken away from TV broadcasting
and re-allocated. Four of those channels (63,64,68,69) with 24 MHz of
bandwidth will be rel-allocated to police, fire, rescue/emergency
services. The remainder (except for UHF 55 which has already been
re-assigned) will be sold off at a government mega-auction. You may have
read about this, but most articles do a poor job of explaining where the
frequency bands are coming from.

After February 17, 2009, Digital TV broadcasting will take place on
VHF 2 to 13, UHF 14 to 51. Only 37 full power stations have chosen to
broadcast on VHF 2 to 6. Some 450 full power stations will be on upper
VHF 7 to 13, the remainder on UHF.

As for what you should see on the analog tuner for a digital station,
it will likely show nothing. The ATSC signal, while it is in the same 6
MHz spacing as analog, is very different from NTSC.

If you want to find the digital stations near you and their actual
broadcast channel, try antennaweb.org. Enter your zip code and a high
antenna height under options to get a complete list of the local digital
stations. The last number on each station line is the current actual
broadcast channel.

In February, 2009, 517 stations will change their digital channel to
their current analog NTSC channel. There are another 117 stations that
will have to move their digital channel to another one. Many of these
are because their current digital channel is in UHF 52 to 69 (called out
of core), there is a channel interference issue or they want a better
channel for their location. People need to know this when they select
their antenna. UHF only may not be sufficient in many markets.

Actually, some of these stations may shut down their analog channel
before February, 2009 if they need to. The FCC released a long 154 page
document on the digital transition plan for full power stations on
December 31, 2007. 215 numbered paragraphs and 623 footnotes! The
document is at http://www.fcc.gov/dtv/ if anyone wants to try to get
some insight into the complexity of the process. Think of it as light
bedtime reading on the laptop! :D The list of final digital channel
assignments is further down that webpage, posted on August 6, 2007.

Whew, that was a long info dump post... Oops.
Alan F

RF signal strength
 

"JohnR66" wrote in message
...
I understand HDTV brodcasts will use the UHF channels. I can pick up
analog
ones from clear to mild snow. How poor of signal until digital drops out?

An approximate answer requires the signal to be 15 db above the noise.
Typicially this ratio is somewhat greater. As a contrast, analog TV
requires about 40db signal to noise ratio for no snow precepribility.

When tuning an analog TV to digital frequency, shouldn't I hear or see
something different other than the regular back ground noise? I tried all
channels without analog brodcasts and they are plain noise and snow.

No, the data stream is deliberately pseudo-randomized to produce a flat
continuous RF spectrum. If the data were not randomized there would be holes
in the spectrum, resulting in wasted bandwidth and may interfere with nearby
channels. When tuned by an NTSC analog tuner, the digital signal looks like
snow.
Check out www.atsc.org for more detail.

RF signal strength
 

In article "JohnR66" writes:
I understand HDTV brodcasts will use the UHF channels. I can pick up analog

Your understanding is flawed. Digital (which includes HDTV) can be VHF or
UHF. So, it does use the UHF channels, but not exclusively.


ones from clear to mild snow. How poor of signal until digital drops out?

Depends on what is making it poor. Some forms of interference are worse
than others.


Is it true, the low and hi band VHF gets turned over to police and fire? No
more bulky antenna!

It is not true.

When tuning an analog TV to digital frequency, shouldn't I hear or see
something different other than the regular back ground noise?

No.

I tried all
channels without analog brodcasts and they are plain noise and snow. I know
the PBS station is digital around here.

Any good website with technical details?

Yes. http://www.google.com/


Alan