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  #91  
Old Yesterday, 11:10 AM posted to microsoft.public.windowsxp.general
Mark Twain
external usenet poster
 
Posts: 2,049
Default O.T. Macrium

Here's my map/report:

http://www.tvfool.com/?option=com_wr...edf2a217378 e

I guess I live in the woods *L*
actually the desert with hills
around me.

I didn't think I would get much.

I'm wondering if it's even worth
it? Maybe stick to my DVD's like
before. There's not much on TV
anyway.

I bought this Terk Tower for the
tuner before it got fried but it
only picked up one more station
although I did notice the signal
was 'cleaner' and didn't drift.

The green light is actually a
adjustment for + or -


https://www.ebay.com/itm/TERK-Amplif...rd!92544!US!-1


Now the weird part of this is,. I
have a cheap clock radio and it picks
up allot of stations as well as my car
radio.

Now how can they pick up the stations
but a dedicated quality stereo tuner
can't?


Thanks,
Robert
Ads
  #92  
Old Yesterday, 11:39 AM posted to microsoft.public.windowsxp.general,uk.tech.broadcast
J. P. Gilliver (John)[_4_]
external usenet poster
 
Posts: 1,040
Default O.T. Macrium (now OT - television reception!)

In message , Paul
writes:
Mark Twain wrote:
I thought I had a balun and rabbit ears
In fact, I know I do, but damned if I can
find it. In any case, I decided to buy this:

https://www.ebay.com/itm/TERK-TVOMA1...idirectional-F
lat-Digital-HDTV-Antenna-/302565532675?_trksid=p5731.m3795
what do you think?
I found the HDMI input under Video
http://www.lg.com/us/tvs/lg-28LN4500-led-tv

[]
Thanks,
Robert


I couldn't find a good reference on the square antenna.
It could be hiding this sort of thing inside. A fractal
antenna. They don't have to use wire for those, and the
antenna could be made from FR4 with copper tracks on it
in the desired pattern. The phasing on some of these,
is intended to combine the signals and drop the characteristic
impedance. Which is how the antennas in the examples here,
manage to get a bit closer to 75 ohms. That's what the
two "rails" in the center are for. Impedance conversion.

http://www.instructables.com/id/How-...nna-for-HDTV-D
TV-plus-/

When I needed an antenna, I build a Gray-Hoverman. One with
extra elements for VHF. And that's because the bureaucrats


Is that better than a Yagi? (I once got hold of Yagi's original paper:
surprisingly long ago - 1920s I think. [When he wrote it, I mean - I'm
not that old!])

here thought it would be cool to give the TV industry zero
dollars to subsidize new transmission equipment. And a side
effect, is a couple transmitters just used the old analog
setup, on something like channel 6. They changed the
modulation of the transmitter, for the digital signal,
but the "power" part is just the old equipment.

It means our channels here, they could have all been placed
on UHF (simplifying things and making the square antenna
more practical), but instead the band remains split between
some stations being on VHF and the rest being on UHF. Then
it means a physically larger antenna to get VHF. UHF works
with smaller dimensions. If I only needed a UHF
antenna, I could have continued using my old one.


Whereas here in UK, things went the other way: VHF would have covered
the country with far fewer transmitters (and did), but we went to UHF
for 625 lines (what some call "PAL", though strictly that's the colour
method), so that the existing VHF network could continue to supply the
old 405 line system. (Which remained operating until I think 197x!)

My Gray Hoverman was designed "for the cottage" rather than
an urban setting. To use it in the city, I'd need a rotator
because it only has a 15 degree beamwidth. Since I have
TV transmitters on two major different vectors, it requires
rotating the antenna to either vector to get a signal.


Or two aerials. (I don't think I've ever seen a domestic TV aerial here
with a rotator; but, we are very fortunate that our networks were mostly
designed to co-site the transmitters.)

It the antenna is isotropic, and has a wide beam width,
then you hardly ever need to fiddle with it.


Though few, at least those with wire elements, are truly isotropic.

In one of the TV forums, the "experts" there never buy
an antenna, without seeing the beam pattern versus
frequency. And I was hoping to find a little backgrounder
on the square antenna, with some good pictures of results.
As that helps predict whether it'll be a practical
purchase or not.

Amplifiers are a good choice for distribution - if you're
driving 100 feet of cheap down-lead, then sticking an amp
on the head end, might help reduce the loss. Amplifiers
always have a "noise figure", and indiscriminate use of
amps leads to a degradation in the noise part of "S/N".


Yes, amplified room aerials aren't in general of that much benefit,
unless your TV is particularly deaf. In general, I wouldn't buy a
"by-the-set" amplifier (except for signal splitting between two or more
sets) unless it had a noise figure mentioned on the box, and few such do
have. As you say, other end of downlead is a different matter.

So a 60dB amp isn't "twice as good" as a 30dB amp,
or a loaf of bread baked for twice as long is burned,
rather than being "twice as good". So if you see


I like that analogy!

exaggerated claims for the amp, keep that in mind :-)

The TV has AGC (automatic gain control on RF) and
probably works from 10uV to 1V or so in amplitude.
The TV will turn up its own gain on a weak signal.


Indeed. A stated noise figure would be good there too, but again is very
rare; even a uV one is, I think.

One difference with DTV, is the response to the signal.
You can go from a crystal clear picture, to a black screen
(LOS) with only a 2dB drop in level. There isn't
nearly the graceful degradation as there was with
analog NTSC. A missing channel could be close to the

(And analog PAL.)
right level, or way way down and totally out of reach,
and you can't really tell.


This (combined with the more or less total decline in technical support
from the broadcasters from the general public) has also allowed other
near band - actually in-band for most equipment, as they keep
reallocating bits of the band to the ravenous mobile (cellular) section
- to increase with impunity; with analogue signals, viewers could see
that what was stopping them viewing properly was interference, but with
digital, they just suffer in silence (and frustration).

One amazing thing that happened here, was getting a
TV tuner card for the PC and comparing it to my
settop box. A world of difference. The STB could
only get three channels regularly. The TV tuner
card (using the same signal) gets everything known
to exist in the city. While propagation characteristics
change from month to month, the difference I'm seeing
really looks like the TV tuner does something different
from a DSP perspective. As I don't think this is
just "moar amp". It's not an amplifier effect.


Despite what I said above about room amplifiers, I was very agreeably
surprised recently when trying out a TV stick that came with an
"amplified aerial" (telescopic rod, but needed a separate USB socket to
power it); it got most of the channels available in the area, where I'd
expected to need to connect the roof aerial. (I _was_ trying upstairs.)
It even got usable signals - some breakup - from many of the channels
from an another transmitter site. (I was at NE6 5AD - main signals from
Pontop Pike, others possibly from one of its fill-ins [Fenham?].) I
_didn't_ try it without the aerial powered, to see if just the stick was
more sensitive than they've been in the past (it might not have worked
at all unpowered, anyway).

It's fun to play with. Too bad I'm not all that interested
in TV :-)

(-:

Paul

John
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)[email protected]+H+Sh0!:`)DNAf

The squeamish will squeam a lot.
(Barry Norman on the film "300", in Radio Times 30 March-5 April 2013.)
  #93  
Old Yesterday, 12:54 PM posted to microsoft.public.windowsxp.general
Paul[_32_]
external usenet poster
 
Posts: 4,876
Default O.T. Macrium

Mark Twain wrote:
Here's my map/report:

http://www.tvfool.com/?option=com_wr...edf2a217378 e

I guess I live in the woods *L*
actually the desert with hills
around me.

I didn't think I would get much.

I'm wondering if it's even worth
it? Maybe stick to my DVD's like
before. There's not much on TV
anyway.

I bought this Terk Tower for the
tuner before it got fried but it
only picked up one more station
although I did notice the signal
was 'cleaner' and didn't drift.

The green light is actually a
adjustment for + or -


https://www.ebay.com/itm/TERK-Amplif...rd!92544!US!-1


Now the weird part of this is,. I
have a cheap clock radio and it picks
up allot of stations as well as my car
radio.

Now how can they pick up the stations
but a dedicated quality stereo tuner
can't?


Thanks,
Robert


I'm not really good with FM, so I can't tell
you why the Clock Radio is better. The clock
radio can use a ferrite bar for AM, but they
probably wouldn't do that for FM. Ferrite does
go up to fairly high frequencies, but I haven't
run into an example of doing FM that way. And
there isn't room for much of an FM structure
inside a radio.

I tried a 300ohm antenna for FM here, which is
really just a "bag full of wire", and I can't
say it was "sensitive" at all. I couldn't receive
like I was running a shortwave radio or anything.

*******

Your TV map has a couple VHF stations (10 and 5) and
one UHF (25). The products you've been looking at which
are mainly UHF band, are going to make getting 25
easier. I can't promise you how the "10 and 5" are
going to work out.

The three stations in question, are all in the same
direction. So you only need to point the antenna
once for the three of them.

The question would be, what kind of smallish antenna
would give good coverage on UHF and VHF. The people
selling them aren't very honest about this.

*******

This is mine, only mine has a completely different
support structure :-) Mine looks like a clothes
dryer rack, with four vertical pipes and sits on
the floor. Mine isn't intended for outdoor use
like this one is. Mine was intended to sit on the floor
somewhere (original intent was in an attic with
a tall ceiling above it). But it just barely fits
in available space in the living room, for testing.
Roughly $200 in materials went into mine, because
I had some "do-overs". I actually made a "drill assist"
for a hand drill, to emulate a drill press in an attempt
to make holes in stuff, with less than one degree of
positional error. I used a foot long drill bit from
the hardware store, sized to drill holes for the copper
tubing. Based on my material cost, I lost money by
about a factor of two, by DIY. I could have bought
an equivalent antenna for less.

http://www.instructables.com/id/GH10...an-TV-Antenna/

It might not be clear there, but that antenna is 3D and
has depth. It's pretty deep from back to front. But it
would pick up your 10 and 5, and with 100% readings.

A more basic one is here. The zigzag parts are UHF. The
top coupled elements are VHF (and probably weren't present
on the antenna Hoverman designed).

http://www.idc-online.com/technical_...TV_antenna.pdf

That one has a gain curve, and you can see the antenna "peaks"
at 660MHz or so. That's a general shape for UHF antennas,
you can't make them exactly flat over a wide range. The
graph doesn't really go down far enough, as it's not
showing us the important VHF stuff (off the graph
to the left). The antenna in that example, should do well
on your channel 25 (maybe 8dB gain over isotropic).

VHF LOW 05 76-82 MHz VHF HIGH 10 192-198 MHz

UHF 25 536-542 MHz

The top of VHF High is 210-216 MHz and that is channel 13.

*******

Back when I got my STB, this was the one people were talking about.
That's an eight bay antenna (UHF part). It claims

8-Bay HD and UHF outdoor TV antenna picks up UHF band
channels 14 thru 69 with a reception range of 80 miles.

CM 4228HD also picks up High VHF signals within a 45 mile radius,
streaming channels 7 thru 13.

https://www.amazon.com/CHANNEL-CM-42...words=cm4228hd

But in fact, the 4NEC2 analysis showed that channel 9 suffers a
phase inversion and pokes out the back of the antenna. And
since the antenna includes the "grid" in the back as a
reflector, the end result is the antenna has no gain on
channel 9 at all. This puts your channel 10 reception in
danger. And that's why the gain graphs are good for
spotting potential problems.

Now, this one, is an example of a flawed concept. Once
the multi-bay antennas get to a certain size, phasing
becomes an issue. The manufacturer cannot control the
constructive and destructive interference between these
well enough, to obtain consistently high gain. So when
the antenna says "17.4 dB gain", well, we don't know
which exact frequency that happened on, and it might only
be 10dB on channel 25 for all we know. The idea with these
duals, is you point one structure on one vector, the
second structure in a different direction, and "magically"
and obediently, the two signals add without screwing
up one another :-/ Well, not really. Even if you point
them in exactly the same direction, the phasing effects
might leave a bit of ripple in the gain.

https://www.antennasdirect.com/store...V-Antenna.html

*******

Getting back to reality then, I think if you can
locate your rabbit ears, and fully extend them and
you have the balun, that's a start at receiving 5 and 10.

If you think 25 is a good channel, then maybe your
small square purchase would be a good idea. And since all three
of the most powerful stations are on the same vector,
the Terk with the "beam" Yagi concept, might work for
that too. But it's hard to tell with that one, whether
it actually has gain on VHF.

Other than that, 50 feet of 1/4" copper tubing, some
CPVC pipe and solvent cement, a drill, a whole month
of your time, and you can make an antenna like I did :-)
I'm really surprised at one point, I didn't dig a hole
in the back yard, and throw all the materials in there :-)

Paul

  #94  
Old Yesterday, 09:44 PM posted to microsoft.public.windowsxp.general
J. P. Gilliver (John)[_4_]
external usenet poster
 
Posts: 1,040
Default O.T. Macrium - now OT aerials etc. (-:

In message , Mark
Twain writes:
[]
Now the weird part of this is,. I
have a cheap clock radio and it picks
up allot of stations as well as my car
radio.

Now how can they pick up the stations
but a dedicated quality stereo tuner
can't?

[]
The "dedicated quality stereo tuner" probably has a shielding metal
case, and is _designed_ not to receive any signals that don't come in
through it's aerial socket. It may even be less sensitive to signals
coming in there, the assumption being that anyone serious about quality
FM audio will have a good outdoor aerial (with rotator if necessary).
(This can also make it less susceptible to overloading, in circumstances
where that might be a problem.)

Probably less relevant in the case of the FM band, but it used to be the
case for AM sets, especially shortwave, where an unscrupulous salesman
would sweep {an unselective set with poor rejection} across the band,
saying "look at all the stations it can get", when in practice many of
them were intermodulation products generated within the set. But it is
probably still true to say that number of stations picked up is not
directly related to quality of set. (It will be, to some extent anyway,
if _all_ signals are weak. But there are two aspects to the "quality" of
the set: the sensitivity/selectivity/other parameters of the r. f. part
of the set, and the quality of the FM discriminator section and
subsequent audio stages.)
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)[email protected]+H+Sh0!:`)DNAf

Where [other presenters] tackle the world with a box of watercolours, he
takes a spanner. - David Butcher (on Guy Martin), RT 2015/1/31-2/6
  #95  
Old Today, 02:07 AM posted to microsoft.public.windowsxp.general
Mark Twain
external usenet poster
 
Posts: 2,049
Default O.T. Macrium

At this point, I think it's more effort/cost
than it's worth. The only station worthwhile
is channel 5, so I think I'll wait until I
find my rabbit ears and balun and use them.

I didn't know what the Y, Pb, Pr connections
were at first,. but of course I'll be using
the HDMI connection.

I'll have to send the tuner out to be repaired,.
thankfully the Terk Tower wasn't fried.

Many thanks for all your help


Robert
  #96  
Old Today, 09:10 AM posted to microsoft.public.windowsxp.general,uk.tech.broadcast
Brian Gaff
external usenet poster
 
Posts: 16
Default O.T. Macrium (now OT - television reception!)

So you still have vhf tv then? Strange, the band 3 stuff here is basically
dab and land mobile stuff now.
I remember well when tv was actually properly regional, and had varied
programs, I made three band 3 yagis and mounted them on a pole each pointing
at a different station.
IE Anglia, Midlands and Southern as we had then. it was very successful
showing how most of the time long ranges can be achieved with simple
aerials. All were five elements with folded dipoles, nothing special at all.


As for amplification. the problem with mast head amps to get weaker signals
was always intermodulation effects creating phantom signals , noise and
just plain crap.
Its even worse now with mobile phone stuff unfortunately all over the place
and with towers close by.
The best amps in the old days were those made by Pye Labgear. However
Antiference must have been made with use in the wilds of Scotland in mind,
as the slightest signal that was strong anywhere in the vhf or uhf spectrum
trashed their output, yes low noise but noise is not the be and end all of
course!

I've never tried tv sticks. Might be worth a go I suppose if any of the
software is accessible that is, as I'll need some new way to get tv soon as
my old sd goodmans talking box slowly becomes obsolete. I just find it
pretty daft to have to buy a whole tv just to listen to the sound and AD!
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"J. P. Gilliver (John)" wrote in message
...
In message , Paul
writes:
Mark Twain wrote:
I thought I had a balun and rabbit ears
In fact, I know I do, but damned if I can
find it. In any case, I decided to buy this:
https://www.ebay.com/itm/TERK-TVOMA1...idirectional-F
lat-Digital-HDTV-Antenna-/302565532675?_trksid=p5731.m3795
what do you think?
I found the HDMI input under Video
http://www.lg.com/us/tvs/lg-28LN4500-led-tv

[]
Thanks,
Robert


I couldn't find a good reference on the square antenna.
It could be hiding this sort of thing inside. A fractal
antenna. They don't have to use wire for those, and the
antenna could be made from FR4 with copper tracks on it
in the desired pattern. The phasing on some of these,
is intended to combine the signals and drop the characteristic
impedance. Which is how the antennas in the examples here,
manage to get a bit closer to 75 ohms. That's what the
two "rails" in the center are for. Impedance conversion.

http://www.instructables.com/id/How-...nna-for-HDTV-D
TV-plus-/

When I needed an antenna, I build a Gray-Hoverman. One with
extra elements for VHF. And that's because the bureaucrats


Is that better than a Yagi? (I once got hold of Yagi's original paper:
surprisingly long ago - 1920s I think. [When he wrote it, I mean - I'm not
that old!])

here thought it would be cool to give the TV industry zero
dollars to subsidize new transmission equipment. And a side
effect, is a couple transmitters just used the old analog
setup, on something like channel 6. They changed the
modulation of the transmitter, for the digital signal,
but the "power" part is just the old equipment.

It means our channels here, they could have all been placed
on UHF (simplifying things and making the square antenna
more practical), but instead the band remains split between
some stations being on VHF and the rest being on UHF. Then
it means a physically larger antenna to get VHF. UHF works
with smaller dimensions. If I only needed a UHF
antenna, I could have continued using my old one.


Whereas here in UK, things went the other way: VHF would have covered the
country with far fewer transmitters (and did), but we went to UHF for 625
lines (what some call "PAL", though strictly that's the colour method), so
that the existing VHF network could continue to supply the old 405 line
system. (Which remained operating until I think 197x!)

My Gray Hoverman was designed "for the cottage" rather than
an urban setting. To use it in the city, I'd need a rotator
because it only has a 15 degree beamwidth. Since I have
TV transmitters on two major different vectors, it requires
rotating the antenna to either vector to get a signal.


Or two aerials. (I don't think I've ever seen a domestic TV aerial here
with a rotator; but, we are very fortunate that our networks were mostly
designed to co-site the transmitters.)

It the antenna is isotropic, and has a wide beam width,
then you hardly ever need to fiddle with it.


Though few, at least those with wire elements, are truly isotropic.

In one of the TV forums, the "experts" there never buy
an antenna, without seeing the beam pattern versus
frequency. And I was hoping to find a little backgrounder
on the square antenna, with some good pictures of results.
As that helps predict whether it'll be a practical
purchase or not.

Amplifiers are a good choice for distribution - if you're
driving 100 feet of cheap down-lead, then sticking an amp
on the head end, might help reduce the loss. Amplifiers
always have a "noise figure", and indiscriminate use of
amps leads to a degradation in the noise part of "S/N".


Yes, amplified room aerials aren't in general of that much benefit, unless
your TV is particularly deaf. In general, I wouldn't buy a "by-the-set"
amplifier (except for signal splitting between two or more sets) unless it
had a noise figure mentioned on the box, and few such do have. As you say,
other end of downlead is a different matter.

So a 60dB amp isn't "twice as good" as a 30dB amp,
or a loaf of bread baked for twice as long is burned,
rather than being "twice as good". So if you see


I like that analogy!

exaggerated claims for the amp, keep that in mind :-)

The TV has AGC (automatic gain control on RF) and
probably works from 10uV to 1V or so in amplitude.
The TV will turn up its own gain on a weak signal.


Indeed. A stated noise figure would be good there too, but again is very
rare; even a uV one is, I think.

One difference with DTV, is the response to the signal.
You can go from a crystal clear picture, to a black screen
(LOS) with only a 2dB drop in level. There isn't
nearly the graceful degradation as there was with
analog NTSC. A missing channel could be close to the

(And analog PAL.)
right level, or way way down and totally out of reach,
and you can't really tell.


This (combined with the more or less total decline in technical support
from the broadcasters from the general public) has also allowed other near
band - actually in-band for most equipment, as they keep reallocating bits
of the band to the ravenous mobile (cellular) section - to increase with
impunity; with analogue signals, viewers could see that what was stopping
them viewing properly was interference, but with digital, they just suffer
in silence (and frustration).

One amazing thing that happened here, was getting a
TV tuner card for the PC and comparing it to my
settop box. A world of difference. The STB could
only get three channels regularly. The TV tuner
card (using the same signal) gets everything known
to exist in the city. While propagation characteristics
change from month to month, the difference I'm seeing
really looks like the TV tuner does something different
from a DSP perspective. As I don't think this is
just "moar amp". It's not an amplifier effect.


Despite what I said above about room amplifiers, I was very agreeably
surprised recently when trying out a TV stick that came with an "amplified
aerial" (telescopic rod, but needed a separate USB socket to power it); it
got most of the channels available in the area, where I'd expected to need
to connect the roof aerial. (I _was_ trying upstairs.) It even got usable
signals - some breakup - from many of the channels from an another
transmitter site. (I was at NE6 5AD - main signals from Pontop Pike,
others possibly from one of its fill-ins [Fenham?].) I _didn't_ try it
without the aerial powered, to see if just the stick was more sensitive
than they've been in the past (it might not have worked at all unpowered,
anyway).

It's fun to play with. Too bad I'm not all that interested
in TV :-)

(-:

Paul

John
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)[email protected]+H+Sh0!:`)DNAf

The squeamish will squeam a lot.
(Barry Norman on the film "300", in Radio Times 30 March-5 April 2013.)



  #97  
Old Today, 12:03 PM posted to microsoft.public.windowsxp.general,uk.tech.broadcast,alt.windows7.general
J. P. Gilliver (John)[_4_]
external usenet poster
 
Posts: 1,040
Default O.T. Macrium (now OT - television reception!)

In message , Brian Gaff
writes:
So you still have vhf tv then? Strange, the band 3 stuff here is
basically dab and land mobile stuff now. I remember well when tv was


The rest of western Europe still had VHF TV, at least up to the end of
analogue, I don't know since the change to digital; however, they had
more or less the same _type_ of TV signal on both (OK, slight
differences in bandwidths for PAL-D vs PAL-G, but I suspect these didn't
translate into different circuitry after the IF in the receivers),
unlike the UK (and Eire).
[]
I've never tried tv sticks. Might be worth a go I suppose if any of the
software is accessible that is, as I'll need some new way to get tv

(For readers of the two Windows 'groups: Brian is a blind user, so needs
software that interacts with screenreader software. Much graphical
software does not "play well"; the designers of TV stick software tend
not to worry that much, presumably as they think it's a visual thing
anyway!)
soon as my old sd goodmans talking box slowly becomes obsolete. I just
find it pretty daft to have to buy a whole tv just to listen to the
sound and AD!
Brian


From recent - but limited - experience with one: the supplied software
worked to a limited extent with two of the screenreaders we tried
(Narrator [Microsoft] and the four-letter one), but some things didn't
speak. (We wanted to try with Window-Eyes, but we've only got that on an
XP machine, and though the software loaded, the driver wouldn't.) We
found the stick could also be used with VLC: you have to give it the
frequency in MHz, but otherwise it works somewhat better with speech.
But is somewhat less stable.

As for AD the audio description channel, however, that is more of a
problem. (For those who don't know what this is: it is an extra audio
channel, which for certain programmes - often shown as "(AD)" in the
listings mag.s, at least here in the UK - gives an audio description of
what's happening, for VH/VI users of the programme.) With the supplied
software, it was possible to select the AD channel, but it comes out at
the wrong speed - as do certain of the DAB channels. (The particular
stick I chose does DAB/DAB+/FM as well as TV [including DVB-T2, which is
marketed as HD in the UK, unfortunately].) We surmise that it is because
the AD channel (and some DAB channels) are transmitted at lower bit rate
than the main audio (and other DAB channels). With VLC, the AD channel
(and the affected DAB channels) come out at the _correct_ speed. But
this revealed another problem (which I'd known in advance):

For the AD channel as it is included on for example DVDs that have it,
and possibly in some other countries (anyone in US know?), the AD
channel contains the normal audio of the programme, obviously including
dialogue (i. e. where someone is speaking); this is "dipped" when audio
description is required. However, on UK DTV, the AD channel contains
_only_ the audio description, silence otherwise: therefore, for a VH/VI
user wanting to use an AD programme, the set has to receive both the
normal audio _and_ the AD, and dip the normal audio when there is
description - otherwise the VH/VI person will hear "Fred comes into the
room and shoots Jim", but won't hear what Jim said to Fred to provoke
it! And won't hear a car crash, the clink of a glass, or whatever.
Obviously, TVs - and set-top-boxes - sold here that have an AD button on
the remote _do_ do this, but in the case of TV sticks, either they
don't, or at least the _software_ used with them doesn't. (Unless anyone
here can tell me otherwise!)

(End of this posting. What follows left for context - Brian top-posts,
with a proper .sig delimiter that normally causes the tail to be deleted
on the first repost. This helps him.)
--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"J. P. Gilliver (John)" wrote in message
...
In message , Paul
writes:
Mark Twain wrote:
I thought I had a balun and rabbit ears
In fact, I know I do, but damned if I can
find it. In any case, I decided to buy this:
https://www.ebay.com/itm/TERK-TVOMA1...idirectional-F
lat-Digital-HDTV-Antenna-/302565532675?_trksid=p5731.m3795
what do you think?
I found the HDMI input under Video
http://www.lg.com/us/tvs/lg-28LN4500-led-tv

[]
Thanks,
Robert

I couldn't find a good reference on the square antenna.
It could be hiding this sort of thing inside. A fractal
antenna. They don't have to use wire for those, and the
antenna could be made from FR4 with copper tracks on it
in the desired pattern. The phasing on some of these,
is intended to combine the signals and drop the characteristic
impedance. Which is how the antennas in the examples here,
manage to get a bit closer to 75 ohms. That's what the
two "rails" in the center are for. Impedance conversion.

http://www.instructables.com/id/How-...nna-for-HDTV-D
TV-plus-/

When I needed an antenna, I build a Gray-Hoverman. One with
extra elements for VHF. And that's because the bureaucrats


Is that better than a Yagi? (I once got hold of Yagi's original paper:
surprisingly long ago - 1920s I think. [When he wrote it, I mean - I'm not
that old!])

here thought it would be cool to give the TV industry zero
dollars to subsidize new transmission equipment. And a side
effect, is a couple transmitters just used the old analog
setup, on something like channel 6. They changed the
modulation of the transmitter, for the digital signal,
but the "power" part is just the old equipment.

It means our channels here, they could have all been placed
on UHF (simplifying things and making the square antenna
more practical), but instead the band remains split between
some stations being on VHF and the rest being on UHF. Then
it means a physically larger antenna to get VHF. UHF works
with smaller dimensions. If I only needed a UHF
antenna, I could have continued using my old one.


Whereas here in UK, things went the other way: VHF would have covered the
country with far fewer transmitters (and did), but we went to UHF for 625
lines (what some call "PAL", though strictly that's the colour method), so
that the existing VHF network could continue to supply the old 405 line
system. (Which remained operating until I think 197x!)

My Gray Hoverman was designed "for the cottage" rather than
an urban setting. To use it in the city, I'd need a rotator
because it only has a 15 degree beamwidth. Since I have
TV transmitters on two major different vectors, it requires
rotating the antenna to either vector to get a signal.


Or two aerials. (I don't think I've ever seen a domestic TV aerial here
with a rotator; but, we are very fortunate that our networks were mostly
designed to co-site the transmitters.)

It the antenna is isotropic, and has a wide beam width,
then you hardly ever need to fiddle with it.


Though few, at least those with wire elements, are truly isotropic.

In one of the TV forums, the "experts" there never buy
an antenna, without seeing the beam pattern versus
frequency. And I was hoping to find a little backgrounder
on the square antenna, with some good pictures of results.
As that helps predict whether it'll be a practical
purchase or not.

Amplifiers are a good choice for distribution - if you're
driving 100 feet of cheap down-lead, then sticking an amp
on the head end, might help reduce the loss. Amplifiers
always have a "noise figure", and indiscriminate use of
amps leads to a degradation in the noise part of "S/N".


Yes, amplified room aerials aren't in general of that much benefit, unless
your TV is particularly deaf. In general, I wouldn't buy a "by-the-set"
amplifier (except for signal splitting between two or more sets) unless it
had a noise figure mentioned on the box, and few such do have. As you say,
other end of downlead is a different matter.

So a 60dB amp isn't "twice as good" as a 30dB amp,
or a loaf of bread baked for twice as long is burned,
rather than being "twice as good". So if you see


I like that analogy!

exaggerated claims for the amp, keep that in mind :-)

The TV has AGC (automatic gain control on RF) and
probably works from 10uV to 1V or so in amplitude.
The TV will turn up its own gain on a weak signal.


Indeed. A stated noise figure would be good there too, but again is very
rare; even a uV one is, I think.

One difference with DTV, is the response to the signal.
You can go from a crystal clear picture, to a black screen
(LOS) with only a 2dB drop in level. There isn't
nearly the graceful degradation as there was with
analog NTSC. A missing channel could be close to the

(And analog PAL.)
right level, or way way down and totally out of reach,
and you can't really tell.


This (combined with the more or less total decline in technical support
from the broadcasters from the general public) has also allowed other near
band - actually in-band for most equipment, as they keep reallocating bits
of the band to the ravenous mobile (cellular) section - to increase with
impunity; with analogue signals, viewers could see that what was stopping
them viewing properly was interference, but with digital, they just suffer
in silence (and frustration).

One amazing thing that happened here, was getting a
TV tuner card for the PC and comparing it to my
settop box. A world of difference. The STB could
only get three channels regularly. The TV tuner
card (using the same signal) gets everything known
to exist in the city. While propagation characteristics
change from month to month, the difference I'm seeing
really looks like the TV tuner does something different
from a DSP perspective. As I don't think this is
just "moar amp". It's not an amplifier effect.


Despite what I said above about room amplifiers, I was very agreeably
surprised recently when trying out a TV stick that came with an "amplified
aerial" (telescopic rod, but needed a separate USB socket to power it); it
got most of the channels available in the area, where I'd expected to need
to connect the roof aerial. (I _was_ trying upstairs.) It even got usable
signals - some breakup - from many of the channels from an another
transmitter site. (I was at NE6 5AD - main signals from Pontop Pike,
others possibly from one of its fill-ins [Fenham?].) I _didn't_ try it
without the aerial powered, to see if just the stick was more sensitive
than they've been in the past (it might not have worked at all unpowered,
anyway).

It's fun to play with. Too bad I'm not all that interested
in TV :-)

(-:

Paul

John
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)[email protected]+H+Sh0!:`)DNAf

The squeamish will squeam a lot.
(Barry Norman on the film "300", in Radio Times 30 March-5 April 2013.)




--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)[email protected]+H+Sh0!:`)DNAf

As we journey through life, discarding baggage along the way, we should keep
an iron grip, to the very end, on the capacity for silliness. It preserves the
soul from desiccation. - Humphrey Lyttelton quoted by Barry Cryer in Radio
Times 10-16 November 2012
 




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