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OTA reception problems

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Anonymous
July 1, 2004 5:06:13 PM

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

I live in the Nashville, TN area, about 15 miles West from the towers
b'csting DTV in my area. The problem is, I live in a "hole" between 2 tall
ridges covered with trees, blocking line-of-sight. I've been able to get
spotty reception on most of the DTV channels, which is encouraging, but I
just can't seem to hold a reliable signal. Here's my setup: 40" Radio
Shack UHF yagi on a 25' mast to a Sylvania set-top HDTV box. Here's the
catch...to receive anything, I have to point the antenna AWAY from the
towers and toward the hill behind my house, so I'm getting 100% reflected
signals. So...should I get as bigger yagi, or would more directionality
hurt on my reflected signals more than help? Or should I go for a
different type, like bow-tie and screen? Or should I keep what I have and
try a pre-amp? If so, any recommendations? Cost IS a factor here, so think
cheap please. It's heartbreaking to see the 1st 20 minutes of CSI in
beautiful HD, then have to switch back to SD! Ouch! Please help!

More about : ota reception problems

Anonymous
July 1, 2004 5:06:14 PM

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

I would definitely suggest trying a pre-amp. Pre-amps are definitely a
mixed blessing/curse for analog, but for digital they seem to be an
unconditional benefit. However, a pre-amp is properly seen as a means of
compensating for the underlying problem rather than addressing the problem
itself.

An el cheapo splitter/amplifier (that is, a splitter with a built-in
amplifier -- Wal-Mart sells these) is perhaps a good first-order
approximation to see how well a pre-amp will do without going through all
the investment of a pre-amp. Of course, the greatest benefit is to have a
proper pre-amp on the antenna rather than something that after the fact
amplifies something that has already travelled unamplified down the coax.
But if the splitter/amplifier makes a difference, then you'll definitely
know that a pre-amp is worth the while.

If, as I suspect, the pre-amp improves things significantly but does not
render a complete cure, then I would suggest a bigger yagi.
Directionality is good. You're trying to focus on a particular signal
source and disregard all other sources.

Finally, check with the broadcasters. You may find that some (most?
all?) of them are operating on reduced power, and when they go to full
power many of your problems may go away. Also, some broadcasters have
directional transmitting antennas.

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.
July 1, 2004 9:32:42 PM

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

I would try to call the local station and ask for the engineer in charge of
the station. I have found many of them are very willing to help with
reception problems. It is worth a shot!



"tvserf" <zgirl@mail.com> wrote in message
news:b1bf3db44c9beabf04154c68642aec19@localhost.talkabouttelevision.com...
> I live in the Nashville, TN area, about 15 miles West from the towers
> b'csting DTV in my area. The problem is, I live in a "hole" between 2 tall
> ridges covered with trees, blocking line-of-sight. I've been able to get
> spotty reception on most of the DTV channels, which is encouraging, but I
> just can't seem to hold a reliable signal. Here's my setup: 40" Radio
> Shack UHF yagi on a 25' mast to a Sylvania set-top HDTV box. Here's the
> catch...to receive anything, I have to point the antenna AWAY from the
> towers and toward the hill behind my house, so I'm getting 100% reflected
> signals. So...should I get as bigger yagi, or would more directionality
> hurt on my reflected signals more than help? Or should I go for a
> different type, like bow-tie and screen? Or should I keep what I have and
> try a pre-amp? If so, any recommendations? Cost IS a factor here, so think
> cheap please. It's heartbreaking to see the 1st 20 minutes of CSI in
> beautiful HD, then have to switch back to SD! Ouch! Please help!
>
Related resources
Anonymous
July 1, 2004 9:32:43 PM

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

Actually, I work at one of the local stations. The chief engineer's office
is 10 feet from me as we speak! I've talked to lots of engineers around
here, and everyone seems to have a different answer. The most common
suggestion is "get a pre-amp", or just a general "try it and see" attitude
on other types of antennae. I was hoping someone with a similar problem or
specific knowledge about reflected signals would respond.
July 1, 2004 10:52:44 PM

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

If that's the case I used an HDTV antenna installer recommended by the chief
engineer. It cost me a few bucks but he had the equipment to see the
signal.


"tvserf" <zgirl@mail.com> wrote in message
news:624df770e813b3e664ece0ad757f8bce@localhost.talkabouttelevision.com...
> Actually, I work at one of the local stations. The chief engineer's office
> is 10 feet from me as we speak! I've talked to lots of engineers around
> here, and everyone seems to have a different answer. The most common
> suggestion is "get a pre-amp", or just a general "try it and see" attitude
> on other types of antennae. I was hoping someone with a similar problem or
> specific knowledge about reflected signals would respond.
>
Anonymous
July 5, 2004 4:27:09 AM

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

"tvserf" <zgirl@mail.com> wrote (in part):

>-How high would you have to raise your mast to get a direct signal?
>
>Unfortunately, no mast will be high enough. The ridge between me and the
>towers is over 200' high, topped with 80' trees, and it's directly across
>the street.

Here's an idea that's so ridiculous that it just might work. Do you
own either ridge, or could you get permission to put something on it?
Such as a large passive reflector that might be more efficient than
the ridge itself.

If there's power available on the ridge, and you're not worried about
a visit from the FCC, a more efficient solution might be an antenna on
the ridge aimed at the stations, feeding a wide-band amp that in turn
feeds another antenna aimed at your house.

I'd insert a few smilies, but I don't really expect anyone to take
this seriously.

E. Ogden <eoyymm@nycap.rr.com>
where yymm is the current year and month
Anonymous
July 5, 2004 5:59:14 AM

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

Bob Miller <robmx@earthlink.net> wrote in
news:0Q1Gc.5086$R36.4977@newsread2.news.pas.earthlink.net:

> I have suggested that with COFDM it would be possible for individual
> home owners or neighborhoods who find themselves outside of a coverage
> area to erect on channel repeaters that they could buy from Radio
> Shack. Even if the FCC doesn't allow it when and if they allow COFDM
> on full power TV stations it could be done with WiMax which is COFDM
> based as well. In fact you could do WiMax with 8-VSB as well.

I think, Bob, that he wants a practical solution for NOW, not a sermon on
the relative merits of COFDM and 8VSB.

A powered relay is probably out of the question (the FCC would probably
butt in), but a passive relay would be street legal and for that you only
need access to the ridge and some antennas. Still, it's a tad
expensive...I'd look at an antenna-mounted preamp with the antenna on a
good reflection first off. If he's getting signal part of the time, it
may be that the reflection is OK but just a bit weak and an antenna-
mounted preamp of good quality can altogether fix that problem.

--
Dave Oldridge+
ICQ 1800667

A false witness is worse than no witness at all.
Anonymous
July 5, 2004 8:48:24 AM

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

Go with the channel master 4228 bow tie.

Jeff B
Anonymous
July 5, 2004 5:11:40 PM

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

> Here's an idea that's so ridiculous that it just might work. Do you
> own either ridge, or could you get permission to put something on it?
> Such as a large passive reflector that might be more efficient than
> the ridge itself.

Actually, I do own the ridge behind my house (the one I'm using as a
reflector). There is no power there other that what I string from my
house. I had considered tring to improve the reflective
capabilities...I've already trimmed all the brush from the area the
antenna is pointed at and it did make a small difference. I wonder, would
some other surface, metal or wood, work? Is this what you mean by 'passive
reflector'? I'm not sure how big it needs to be. The point of reflection
is low and close to the antenna, about 20 yards up the hill. I'm guessing
the closer the point of refection is to the antenna, the smaller a
reflector would need to be? Also, how critical is the angle of the
reflector?
Anonymous
July 5, 2004 10:13:58 PM

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

"tvserf" <zgirl@mail.com> wrote:

>> Here's an idea that's so ridiculous that it just might work. Do you
>> own either ridge, or could you get permission to put something on it?
>> Such as a large passive reflector that might be more efficient than
>> the ridge itself.
>
>Actually, I do own the ridge behind my house (the one I'm using as a
>reflector). There is no power there other that what I string from my
>house. I had considered tring to improve the reflective
>capabilities...I've already trimmed all the brush from the area the
>antenna is pointed at and it did make a small difference. I wonder, would
>some other surface, metal or wood, work? Is this what you mean by 'passive
>reflector'? I'm not sure how big it needs to be. The point of reflection
>is low and close to the antenna, about 20 yards up the hill. I'm guessing
>the closer the point of refection is to the antenna, the smaller a
>reflector would need to be? Also, how critical is the angle of the
>reflector?

I'm thinking metal. Wood doesn't reflect RF very well (after all,
you've already got plenty of wood there). Could be another material
with a metal surface. Doesn't have to be solid either; a mesh should
do. Don't know how big the holes can be, but the lower the frequency
the bigger the holes and it still looks solid to the signal. Window
screen? Aluminum (not vinyl) siding? Dunno; I never tried anything
like that. It was just an idea off the top of my head. Maybe others
here can advise you.

The ideal shape might be a parabola with the focus at your antenna,
which would require some math. The focus of any satellite dish is
much too short. Probably easier to just use a more-or-less flat plate
angled to bounce the signal down to you. Also don't know if it's
better to ground it or not. A ham might know, but I never was one.

E. Ogden <eoyymm@nycap.rr.com>
where yymm is the current year and month
Anonymous
July 5, 2004 10:42:59 PM

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

On Mon, 05 Jul 2004 13:11:40 -0400, "tvserf" <zgirl@mail.com> wrote:

>> Here's an idea that's so ridiculous that it just might work. Do you
>> own either ridge, or could you get permission to put something on it?
>> Such as a large passive reflector that might be more efficient than
>> the ridge itself.
>
>Actually, I do own the ridge behind my house (the one I'm using as a
>reflector). There is no power there other that what I string from my
>house. I had considered tring to improve the reflective
>capabilities...I've already trimmed all the brush from the area the
>antenna is pointed at and it did make a small difference. I wonder, would
>some other surface, metal or wood, work? Is this what you mean by 'passive
>reflector'? I'm not sure how big it needs to be. The point of reflection
>is low and close to the antenna, about 20 yards up the hill.

Total distance to the spot you cleared? Move the antenna there?
Otherwise search for corner reflector on google.com
Anonymous
July 6, 2004 2:32:11 AM

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

"tvserf" <zgirl@mail.com> wrote in
news:608cb3c09c496212a2f24eca32820a9e@localhost.talkabouttelevision.com:

>> Here's an idea that's so ridiculous that it just might work. Do you
>> own either ridge, or could you get permission to put something on it?
>> Such as a large passive reflector that might be more efficient than
>> the ridge itself.
>
> Actually, I do own the ridge behind my house (the one I'm using as a
> reflector). There is no power there other that what I string from my
> house. I had considered tring to improve the reflective
> capabilities...I've already trimmed all the brush from the area the
> antenna is pointed at and it did make a small difference. I wonder,
> would some other surface, metal or wood, work? Is this what you mean
> by 'passive reflector'? I'm not sure how big it needs to be. The point
> of reflection is low and close to the antenna, about 20 yards up the
> hill. I'm guessing the closer the point of refection is to the
> antenna, the smaller a reflector would need to be? Also, how critical
> is the angle of the reflector?

Yes, a piece of sheet metal, positioned properly so as to reflect the
signal TO your antenna and large enough to reflect some decent amount of
signal might do it quite well. If you can get an analog signal from the
same tower and a pair of walkie talkies and someone to coordinate with
you, it might just be the exact ticket. Put the reflector directly in
the antenna's path and then orient it so that its normal (a line
perpendicular to the surface) bisects the angle between your antenna and
the transmitter. If you can get audio on an analog signal from the same
tower, then you can probably peak it on that and do ok...

Size is important. Anything under a half wave is almost useless.

--
Dave Oldridge+
ICQ 1800667

A false witness is worse than no witness at all.
!