ATSC DTV On Channel DTV Repeaters
K. B.
To fill in the coverage holes created in the move from
analog to digital TV and to provide seamless mobile DTV
coverage, many stations will need repeaters.
~~~
Kirk Bayne
alt.video.digital-tv Home Page
<http://avdtv.tripod.com/avdtv.htm>
Daniel W. Rouse Jr.
news:jmmve5p6fga2l3i1n...@4ax.com...
> <http://www.tvtechnology.com/article/89672>
>
> To fill in the coverage holes created in the move from
> analog to digital TV and to provide seamless mobile DTV
> coverage, many stations will need repeaters.
>
were referred to as "digital translators". Somehow, everyone knew it was
going to be necessary, and yet any significant effort to build and test
these repeaters have been non-existent at best.
The followup question is this: since DTV signal propagation/reception is
essentially destroyed by most factors that previously only introduced extra
noise with analog reception, will these repeaters actually have more of a
negative effect on DTV propagation/reception than an actual improvement?
Bill Cohn
than good? Why would a broadcaster spend money on a fill in repeater
that made reception worse? That seems very counter intuitive to me. Do
you have some sort of insight that the rest of the experts don't have here?
I have heard that that trials of on channel repeaters in the New York
metro area went very well. Roll out of this technology would require a
few rule changes at the FCC as per the article by Doug Lung quoted
above. So don't expect instant gratification on this technology.
Bill Cohn
Andy from Dover
"Bill Cohn" <bill...@comcast.net> wrote in message
news:hcpj4m$fju$1...@news.eternal-september.org...
WTVE-DT is doing this around Philadelpahia
http://en.wikipedia.org/wiki/WTVE
from the article
"The station transmits from sites in or near:
WTVE-DTS1 Reading, PA (225m 0.76kW DA)
WTVE-DTS2 Bethlehem, PA (155m 2.8kW DA)
WTVE-DTS3 North East, MD (87m 0.11kW DA)
WTVE-DTS4 Quarryville, PA (193m 1.0kW DA)
WTVE-DTS5 Myerstown, PA (63m 1.15kW DA)
WTVE-DTS6 Lambertville, NJ (95m 0.6kW DA)
WTVE-DTS7 Philadelphia, PA (378m 126kW DA)
WTVE-DTS8 Brockton, PA (138m 4.25kW DA)"
I'm in Dover Delaware and always get WTVE DT-25 solid with an attic aerial
(rat shack flying saucer). A good idea that seems to work. :-)
Gordon Burditt
>than good?
It would seem logical that repeaters might cause multipath, which
seems deadly to digital TV. There may be ways to avoid much of the
problem, but I doubt that it can be eliminated entirely.
There isn't, for example, a way to construct a RF-channel-23-proof-wall
between areas best served by the repeater and areas best served by
the main transmitter, without (a) messing up RF channel 26, (b)
causing problems with automobile traffic, (c) causing problems with
air traffic, (d) killing plants from lack of sun, or (e) lots of
complaints from homeowner's association nazis that the wall is ugly.
>Why would a broadcaster spend money on a fill in repeater
>that made reception worse?
They might not *know* that until they try it.
Stations have been surprised before that their receiption is a lot
worse than expected at the initial frequency and power levels they
started with, leading to requests for changes.
I also wonder if it's true that just about any change you make to
a broadcasting setup (e.g. double the power, re-aim the antenna,
add a repeater, etc.) will make reception worse *somewhere* (not
necessarily a location where there's a TV, like in the middle of
an ocean), even if the overall effect is an improvement. Re-aiming
an antenna to move the dead spot from a population center to a spot
in the middle of an ocean is a net win, but Too Many Tools on that
island may not think so.
>That seems very counter intuitive to me. Do
>you have some sort of insight that the rest of the experts don't have here?
Experts don't know everything in advance of testing. That's one
reason why they do testing. Modelling the internal structure of
every tall building and tree is a bit more effort than they can
afford.
Daniel W. Rouse Jr.
news:hcpj4m$fju$1...@news.eternal-september.org...
>> "K. B." <hotmail.com@lis2lis2> wrote in message
>> news:jmmve5p6fga2l3i1n...@4ax.com...
>>> <http://www.tvtechnology.com/article/89672>
>>>
>>> To fill in the coverage holes created in the move from
>>> analog to digital TV and to provide seamless mobile DTV
>>> coverage, many stations will need repeaters.
>>>
>> This was also previously mentioned before the mandatory transition when
>> they were referred to as "digital translators". Somehow, everyone knew it
>> was going to be necessary, and yet any significant effort to build and
>> test these repeaters have been non-existent at best.
>>
>> The followup question is this: since DTV signal propagation/reception is
>> essentially destroyed by most factors that previously only introduced
>> extra noise with analog reception, will these repeaters actually have
>> more of a negative effect on DTV propagation/reception than an actual
>> improvement?
>>
> How do you come to the conclusion that the repeaters would do more harm
> than good? Why would a broadcaster spend money on a fill in repeater that
> made reception worse? That seems very counter intuitive to me. Do you have
> some sort of insight that the rest of the experts don't have here?
>
actual conclusion was reached.
> I have heard that that trials of on channel repeaters in the New York
> metro area went very well. Roll out of this technology would require a few
> rule changes at the FCC as per the article by Doug Lung quoted above. So
> don't expect instant gratification on this technology.
>
Are these trials being reported with the same amount of optimism as the DTV
signal calculations? It was obvious that the projections and mathematical
models were skewed towards a better than actual representation of signal
reception as soon as problems started being reported in areas that were
projected to have good or moderate signal levels, so now are these repeaters
also being reported/projected to work better than they actually do?
K. B.
them to become involved in trying out on-channel DTV
Repeaters.
TJ
Any mathematical model is only as good as the assumptions used to create
it, and often factors may be incorrectly considered insignificant until
the Real World proves them otherwise.
Consider the various models used to predict weather. Each uses different
assumptions, and they frequently disagree on what they predict. When
they disagree they can't possibly *all* be right, yet there is a
significant chance they *all* are wrong. Statistically, that skews the
results toward being wrong more often than they are right. Yet we still
find them useful, even though all are flawed.
While TV signal patterns aren't as complex as the weather, they
apparently aren't as simple to predict as they were initially believed
to be. Refinement of these models takes time, as the weight of various
factors and assumptions is reassessed. Most likely, they will never
become refined enough to tell you which type and position of antenna
will function to your particular standards within a particular room of a
particular house.
Yes, the confidence expressed by those reporting the early predictions
was too high, but that was done for the simple reason that few "experts"
ever want to admit they may be wrong.
TJ
GMAN
>"K. B." <hotmail.com@lis2lis2> wrote in message
>news:jmmve5p6fga2l3i1n...@4ax.com...
>> <http://www.tvtechnology.com/article/89672>
>>
>> To fill in the coverage holes created in the move from
>> analog to digital TV and to provide seamless mobile DTV
>> coverage, many stations will need repeaters.
>>
>This was also previously mentioned before the mandatory transition when they
>were referred to as "digital translators". Somehow, everyone knew it was
>going to be necessary, and yet any significant effort to build and test
>these repeaters have been non-existent at best.
Nothing has to be done to the 1000's of repeaters out there already other than
to update the hardware inside. they are already setup with the proper UHF
towers and broadcasting antenna's . they just need the rackmount equipment
updated.