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Digital TV questions

J

James Goforth

Jan 1, 1970
0
I have a few questions regarding the upcoming conversion to digital
with over-the-air broadcasts. Please forgive my naivete.
1: Are the digital signals, which have become available now, being
broadcast in UHF -- while the analog signals are in VHF?
2: If so, when the analog signals are done away with in 2009, will the
digital signals then begin to transmit in VHF? Doesn't a VHF signal
travel much farther than a UHF signal?
3: Is the digital signal expected to travel less distance than the
analog?
4: Are there going to be a lot of places which simply will no longer
get TV reception when February 2009 arrives due to their location? TIA
 
D

Don Bruder

Jan 1, 1970
0
I have a few questions regarding the upcoming conversion to digital
with over-the-air broadcasts. Please forgive my naivete.
1: Are the digital signals, which have become available now, being
broadcast in UHF -- while the analog signals are in VHF?

Depends on the individual station. Some are on VHF, some on UHF. Some
that are currently on VHF will move to UHF after the switch, and might
already be simulcasting their signal on their new digital channel, with
plans to simply cut the power to the analog transmitter on switchover
day. Some will stay put right where they are, some will move to another
channel within the same band. It *TOTALLY* depends on each individual TV
station and the whim of the FCC in assigning broadcast frequencies.
2: If so, when the analog signals are done away with in 2009, will the
digital signals then begin to transmit in VHF?

Exactly the same answer as #1.
Doesn't a VHF signal travel much farther than a UHF signal?

*IN GENERAL*, due to the lower frequency, VHF will "get out" further
than UHF, but this statement can vary in truth based on too many
variables to try covering in a newsgroup posting. You could fill books
trying to cover all the possible variations - terrain, foliage, material
the structure is made of, weather conditions, day vs night, ionospheric
conditions, station power output, antenna altitude (both TX and RX),
sunspot activity - Each and every one of these things (and probably
dozens more that I'm not even going to try to list) can have an effect
on how far a signal (digital or not) can reach.
3: Is the digital signal expected to travel less distance than the
analog?

Assuming everything else in the system (Antenna, power output, location,
etc) remains the same, the signal will be identical. What will change is
the "fringe" areas - If you can get a useful signal now, you'll almost
certainly get a perfect picture when you move to digital. If your signal
now is "iffy", it's likely that it will improve tremendously. If it's
*REALLY* iffy, it's likely that you'll get nothing at all on digital.
Then again, you might be surprised at how much better things are.

Digital TV is, quite literally, "all or nothing", where analog is
anywhere from "Perfect" to "OK, but some snow", to "Just barely
watchable", to "Can't get it at all". If there's enough of a signal for
the tuner to work with, you'll get perfect picture and sound. If not,
you'll get absolutely nothing at all. With digital TV, there is no such
thing as "Well, it's strong enough to make out a picture through all the
snow" like with analog. It's either perfect, or it's nonexistent, with
absolutely no "in between".

Personal observation from making the switch: On analog, I had 3 channels
(Not counting the spanish channel and the three religious stations that
are completely worthless to me) that were useful, plus two more that
*MIGHT* be watchable at any given moment and were subject to fading in
and out, along with 4-5 more that varied from "audio only" to "well,
there's *ALMOST* a picture buried in all that snow". Now, on digital,
using the same antenna, I've got almost two dozen channels I can choose
from, every one of them cable/satellite perfect reception quality. (But
beware... Just because I've got those two dozen channels coming in
perfectly doesn't mean that all of them are worth watching!!! Digital or
not, religious channels are garbage, as far as I'm concerned. Ditto the
spanish, hmong, and ukranian (and two more that I can't even guess at
what language they're using) language stations that I've started picking
up since switching to digital)
4: Are there going to be a lot of places which simply will no longer
get TV reception when February 2009 arrives due to their location?

Once again, digital TV is "all or nothing". Without knowing idiotic
amounts of information about your *EXACT* location, the local
topography, details about your exact setup, where the transmitters are
in your area, and probably half a dozen other things, I (or anybody
else, for that matter) can't even take a reasonable guess at whether
you're going to lose TV, keep it, improve, or get worse.
 
R

Rich Webb

Jan 1, 1970
0
I have a few questions regarding the upcoming conversion to digital
with over-the-air broadcasts. Please forgive my naivete.
1: Are the digital signals, which have become available now, being
broadcast in UHF -- while the analog signals are in VHF?

Mostly, yes.
2: If so, when the analog signals are done away with in 2009, will the
digital signals then begin to transmit in VHF?

Some, yes (VHF-HI); most, no
Doesn't a VHF signal
travel much farther than a UHF signal?

It depends.
3: Is the digital signal expected to travel less distance than the
analog?

It depends.
4: Are there going to be a lot of places which simply will no longer
get TV reception when February 2009 arrives due to their location? TIA

It depends.

Hop over to http://www.tvfool.com and try some of their tools. I've
found that I can get good digital reception with just a set-top UHF loop
antenna down to about a predicted -30 dBm.
 
M

Michael

Jan 1, 1970
0
Don Bruder wrote:
(snip)
Digital TV is, quite literally, "all or nothing", where analog is
anywhere from "Perfect" to "OK, but some snow", to "Just barely
watchable", to "Can't get it at all". If there's enough of a signal for
the tuner to work with, you'll get perfect picture and sound. If not,
you'll get absolutely nothing at all. With digital TV, there is no such
thing as "Well, it's strong enough to make out a picture through all the
snow" like with analog. It's either perfect, or it's nonexistent, with
absolutely no "in between".
(snip)

Um.... not true that DTV is all or nothing. It most certainly can exhibit a symptom that is similar
in appearance to so-called snow, what I call "confetti". I'm speaking of the gay colored blocks
sprinkled all over the picture like confetti that can occur when the signal is flaky. My indoor
antenna is admittedly poor, and I get "OK, but occasional confetti" several times every evening that
I watch. Sometimes the confetti is coincident with the passing of a "junker" vehicle, sometimes
with the passing of an aircraft. Last night I first noticed a new source of disruption: left-overs
were heating in the microwave, and when the microwave shut off and the loud alarm squeeled about
half the the TV picture simultaneously went to confetti for a split second.

So yes, there is "in between" with DTV.
 
I have a few questions regarding the upcoming conversion to digital
with over-the-air broadcasts. Please forgive my naivete.
1: Are the digital signals, which have become available now, being
broadcast in UHF -- while the analog signals are in VHF?
2: If so, when the analog signals are done away with in 2009, will the
digital signals then begin to transmit in VHF? Doesn't a VHF signal
travel much farther than a UHF signal?
3: Is the digital signal expected to travel less distance than the
analog?
4: Are there going to be a lot of places which simply will no longer
get TV reception when February 2009 arrives due to their location? TIA

The stations that are/will be available to you can be found here:
http://www.2150.com/broadcast/default.asp
if you know your latitude and longitude.

If you don't know your lat/long, you can enter your address here:
http://stevemorse.org/jcal/latlon.php
and get the lat/long.

I get about 8 stations with a piece of wire out the back of a digital
converter and about 24 stations with an outdoor UHF antenna ($30 at
Radio Shack) sitting on the workbench in the basement. It should do
even better when mounted in the attic ;-)

John
 
D

Don Bruder

Jan 1, 1970
0
Don Bruder wrote:
(snip)
(snip)

Um.... not true that DTV is all or nothing. It most certainly can exhibit a
symptom that is similar
in appearance to so-called snow, what I call "confetti". I'm speaking of the
gay colored blocks
sprinkled all over the picture like confetti that can occur when the signal
is flaky. My indoor
antenna is admittedly poor, and I get "OK, but occasional confetti" several
times every evening that
I watch. Sometimes the confetti is coincident with the passing of a "junker"
vehicle, sometimes
with the passing of an aircraft. Last night I first noticed a new source of
disruption: left-overs
were heating in the microwave, and when the microwave shut off and the loud
alarm squeeled about
half the the TV picture simultaneously went to confetti for a split second.

So yes, there is "in between" with DTV.

That "confetti" is a manifestation of "nothing" - The signal has dropped
to the point where the tuner/decoder can't cope, so it has nothing to
hand off to the display circuitry. The display circuitry expects image
data in a continuous stream, but since the decoder circuitry has nothing
to give it, the display circuitry basically says "Well, I have to put
*SOMETHING* there, so I'll just use the last thing I got". Which usually
means the last successfully decoded block of image that came out of the
decoder stage. Interrupt the image stream long enough, and you'll end up
with a blank screen.
 
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