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News Feature
My Cat Is Watching HDTV!
And she
isn't alone. Many High-Definition TV owners report that their pets
are having trouble distinguishing the realistic picture from
reality itself.
By Phillip Swann
Washington, D.C. (January 14,
2006) -- The other night, I was
thinking of watching a movie on HBO, but my female housemate
wouldn't let me. She was absorbed in a PBS documentary about birds,
which was broadcast in High-Definition TV.
My female housemate is named Snoopy. She's a five-year-old black
domestic cat.
Yes, my cat watches High-Definition TV.
In fact, she will watch for 20 minutes at a time, particularly if
the show features birds, fish or animals. If she sees a bird flying
on a high-def channel, she will crouch down in the attacker stance
as if the winged creature was right in front of her.
The high-def picture is so clear
and life-like that Snoopy apparently thinks it's
real.
Snoopy,
the HDTV-watching cat.
The Eagle Soars
I first noticed this phenomenon in 2001 when I brought home my
first high-def set. Surfing the dial, I stumbled upon a HDTV
channel that was showing a documentary on the American Bald Eagle.
Snoopy was taking a cat nap in a chair to the left of the TV, but
suddenly looked up and saw an eagle soaring across the screen. She
immediately walked over and began watching -- and she hasn't
stopped yet.
Over the last four and a half years, Snoopy has also shown
remarkable interest in baseball games broadcast in high-def.
(See picture below.) But, oddly, she
totally ignores other sports, such as football and basketball.
(Just like a woman, huh?)
Snoopy watches ESPN's broadcast of Sunday Night
Baseball.
I have told several people in the industry about my HDTV-watching
feline and I have been greeted with skeptical looks at best. I was
beginning to think that either Snoopy (or I) was crazy until I
recently researched the topic on the Internet. There are actually
several message boards filled with comments from high-def owners
saying their pets are watching HDTV -- and having the same trouble
distinguishing the realistic picture from reality.
"My cat attacked the TV when (the high-def
network) HDNet was playing a show about lions," said one high-def
owner at alt.tv.tech.hdtv.
"Our cat generally ignores the TV. But one night there was a show
with wolves. She went over to the screen and tried to touch one,"
said another.
Snoopy watches Winged Migration on
HDNet Movies.
Today, I asked members of the AVS, another
popular message board for high-def owners, if they had ever seen
their pets watch HD. The response was immediate.
"One of our two cats watches HD all the time," said Greg. "It's
funny. I can put it on Animal Planet (a non-HD station) and
he's not that interested. I put it on Discovery HD with animals and
I have to keep him from attacking the screen."
"Frequently I catch my Goldendoodle, Harry,
staring intently into the screen," says another poster. "Both my
dogs react to other animals (on HD channels), especially if there
is audio as well. But Harry watches all sorts of programming."
"My Siamese cat will watch intently when Blue Realm ( a documentary
series on Discovery HD Theater) comes on," said one HD owner. "She
sits right under the screen and watches. Then she will stand on her
hind legs and softly paw at the fish on the screen."
I can relate. Check out the picture of Snoopy below:
Snoopy tries to catch a
fish in a PBS documentary in high-def.
Of course, there have been reports for years of
pets watching TV, regardless of the picture's clarity. In 2003, the
Oxygen cable channel launched Meow TV, a non-HD show dedicated to
the interests of cats. Sponsored by Meow Mix, the 30-minute program
featured videos of birds, squirrels and other cat attractions.
However, Meow TV was cancelled after just a paw full of
episodes.
Perhaps if they brought it back as a HDTV program, it would have
more success.
I know Snoopy would watch.
© TVPredictions.com
Phillip
Swann is president and publisher of TVPredictions.com. He has been
quoted in dozens of publications and broadcast outlets, including
CNN, Fox News, Inside Edition, The New York Times Magazine, The
Washington Post, The Chicago Tribune, The Associated Press and The
Hollywood Reporter. He can be reached at swann@tvpredictions.com or at 703-505-3064.
_______________________________________________________________________________________________________
RF Technology: Doug Lung
TV
Antennas for DTV Reception
Consumer VHF/UHF TV Antenna
In recent columns, I've discussed options for TV-transmitting
antennas. This month, I'll look at the other end of the path –
outdoor TV-receiving antennas. I'll describe desirable attributes
for DTV reception, look at some of the types of TVantennas
available and tell you how you can build a simple UHF receiving
antenna.
As with transmitting antennas, the main characteristics of
receiving TV antenna are pattern, gain/directionality,
bandwidth/VSWR and size. Before DTV, gain – and to a lesser extent,
bandwidth – were the key specifications. In 2002, TV antenna VSWR
and pattern are equally important – if not the most important –
specifications.
FCC OET-69 interference-free coverage is based on the use of a
directional receive antenna. DTV viewers are assumed to have an
TV antenna with a gain of 4 dB at Channels 2 to 6, 6 dB at
Channels 7 to 13, and 10 dB at Channels 14 to 69. To squeeze in
more channels, front-to-back ratios for receive TV antennas were
also specified. For analog TV, a front-to-back ratio of 6 dB is
used for Channels 2 to 69. For DTV, much higher ratios are required
– 10 dB for Channels 2 to 6, 12 dB for Channels 7 to 13, and 14 dB
for Channels 14 to 69.
In determining how well an TV antenna will work with DTV
signals, VSWR has to be considered. The Association of Federal
Communications Consulting Engineers (AFCCE), in its Consolidated
Opposition to Petitions for Reconsideration to the FCC's Sixth
Report and Order on Advanced Television Systems, noted "The
effective noise figure, the noise figure subject to a typical
mismatch between the receive TV antenna and the receiver's input,
is higher by at least 3 dB for a VSWR of 2:1. VSWR as high as 5:1
can be expected in practical installations."
The AFCCE concluded that the DTV receiver's noise figure would
have to be better than 4 dB when a 7 dB noise figure is used as the
basis for determining coverage.
In addition to the signal loss associated with a high TV antenna
VSWR, group delay will also be affected. The effect on the
signal-to-noise ratio or error vector magnitude is the same on the
receive side as on the transmitter side.
Fortunately, if a low-noise
amplifier (LNA) is mounted at the antenna, the impact of
TV antenna VSWR is greatly reduced. The output of the LNA should
provide a good match for the coax lead-in and a low VSWR at the
tuner.
COMPARISON SHOPPING
There are several ways to cover the span from 54 to 216 MHz.
Log-period TV antennas perform well over frequency ranges larger
than this while maintaining a low VSWR. However, gain is low
relative to boom length required, and the feed system is complex.
Did you ever look at an outdoor TV antenna and wonder why it was
built that way? VHF TV antenna design is a challenge, since
antennas have to operate from 54 to 88 MHz (a 1.6:1 range) and 174
to 216 MHz (a 1.2:1 range) – a total range of 4:1!
A half wavelength dipole at Channel 2 (54 MHz) will be 9.1 feet
long. At Channel 13 (210 MHz), the dipole is only 2.3 feet long.
Although it isn't practical to use one dipole to cover the entire
54 to 216 MHz range, dipoles also work well at odd harmonics of
their half wavelength resonant frequency. A dipole antenna that
covers 54 to 88 MHz should also work from 164 to 264 MHz.
Some consumer TV antennas take advantage of the 3-to-1
relationship between the low VHF and high VHF bands. Antennas that
depend on this harmonic relationship are swept forward. The reason
is that above resonance, the dipole pattern starts to change from a
figure 8 – with lobes perpendicular to the dipole – to one that
looks more like a four-leaf clover.
Bending the dipole elements forward reduces the beam splitting
in the direction the elements are swept. Other tricks to improve
the pattern include adding "whiskers" to each element about a
quarter wavelength from the feed point.
The picture shows a common low-gain urban VHF/UHF antenna. Each
of the dipole elements is driven, giving the TV antenna a better
front-to-side ratio than would be possible if parasitic elements
were used and – if the dipoles are tapered – improves the
bandwidth.
"Thicker" dipole elements (or an array of elements) would also
provide a wider bandwidth. Many TV antennas use interlaced
high-band and low-band VHF elements. The driven element can be a
series of swept dipoles described above with interleaved parasitic
elements for each band.
How do these VHF antennas compare with planning factors used to
determine DTV coverage? At least for textbook designs, it isn't too
difficult to obtain the correct gain and front-to-back ratio. VWSR,
however, is another issue.
As noted by the AFCCE, VSWR of up to 5:1 can be expected.
UHF-receive TV antenna designs tend to be much simpler, because
they only need to cover 470 to 806 MHz, a 1.7:1 range. When UHF TV
moves to the core channels, the range will drop to 470 to 698 MHz
(1.5:1).
A popular TV antenna design of the past used four stacked
dipole-driven elements in front of a screen. As at VHF,
well-crafted log-periodic designs provide excellent performance
across the UHF band. The gain versus boom length is not as much of
an issue at UHF.
Another TV antenna well-suited to the UHF TV frequency range is
the V or rhombic antenna. These are easy to construct, but their
size makes them impractical for most consumer uses. For this
discussion, it helps to know that a half wavelength at 470 MHz
(Channel 14) is 12.6 inches and at 806 MHz (Channel 69), 7.3
inches.
A typical single UHF bow-tie (triangular) dipole TV antenna in
front of a reflector will have a gain above a dipole ranging from
just under 6 dB at Channel 14, to 10 dB at Channel 69. A stacked
four-bay bow-tie dipole antenna in front of a screen provides gain
ranging from around 11 dB at Channel 14, to approximately 15 dB at
Channel 69.
A typical UHF bow-tie using a corner reflector has about 2 dB
more gain than one using a flat screen: 8 dB to 12 dB from Channel
14 to 69.
As with VHF TV antennas, differences between manufacturers make
it hard to specify a typical VSWR for a particular type of TV
antenna. However, the simpler feed system of the single dipole in
front of a corner reflector should give it an advantage over the
more complicated multiple-bay bow-tie design. I've found the
performance of the simple corner reflector bow-tie antenna to be
similar to that of the four-bay bow-tie and often better than some
corner reflector/ dipole/parasitic director combinations.
How does the performance of these UHF TV antennas compare with
the DTV planning factors? The gain numbers seem reasonable – at
least at midband and higher – for the four-bay bow-tie and corner
reflector antennas. At the low end of the band, they may come up
short. But what happens to the front-to-back ratio?
For a corner reflector or a dipole in front of a screen, the
size of the corner reflector or screen will determine the ratio at
the low end of the band and the size of the opening (or spacing
between horizontal members of the reflector) will determine the
performance at higher channels. The corner reflector dipole/Yagi in
the photo (Consumer VHF/UHF TV Antenna) would probably not meet the
required 14 dB front-to-back ratio at all UHF frequencies.
BUILD YOUR OWN TV Antenna!
Although the bow-tie dipoles have a reasonable response over the
UHF TV band, there are better options. Log-periodic antennas are
the usual choice, but a "do-it-yourself" option is a V or a
rhombic. The V antenna consists of two elements forming a "V."
Ideally each of the elements should be four wavelengths or more in
length at the lowest frequency, although gain is reasonable even at
three wavelengths.
To build a V TV antenna, it can be as easy as arranging two
six-foot rods 50 degrees apart. Gain will be over 5 dB at the low
end of the UHF band, where each side of the V is just under three
wavelengths – and increase smoothly toward the high end of the
band, to over 8 dB.
Two V TV antennas are easily stacked about 12 inches apart to
provide gains over 12 dB at Channel 69. The impedance of the V TV
antenna will be higher than the 300 ohms available from the
ubiquitous 300-ohm TV balun, but it is consistent and close enough
that the VSWR should be better than 2:1 across the UHF band.
One problem with the TV antenna is that it is bidirectional. The
front-to-back ratio is 0 dB. If you need a high front-to-back ratio
and are only interested in one or two channels, one of the two
stacked V antennas can be moved a quarter of a wavelength behind
the other and fed 90 degrees out of phase. However, there is an
easier approach – the rhombic.
Fig. 1 shows a drawing of a rhombiTV antenna with four
elements. Each element of the antenna ("L" in Fig. 1) should be
equal and ideally 60 inches or longer. The angle between the
elements is still 50 degrees (130 degrees on each side). At the end
opposite the feed point, terminate the antenna with a 470-ohm
resistor. (The value of this resistor can be adjusted to maximize
the front-to-back ratio to 20 dB or more.)
Gain is over 12 dB with elements five wavelengths long. If this
seems low, remember that half the power is lost in the 470-ohm
terminating resistor.
_______________________________________________________________________________________________________
From the Chicago Tribune
James Coates:
Computers
Old-fashioned TV antenna can help you catch high-def
signals
January 17, 2006
Q. I have a question about my TV set -- I bought a Sony HDTV last
summer.Unfortunately, my satellite receiver isn't capable of
bringing in the HD signals. The HD-DVR box put out by DirecTV was
more than $900 when I bought the TV last summer and beyond what I
can afford. I'm still waiting for prices to come down.
I really want to be able to see the high-definition quality
and be able to record shows in HD too. I have TiVo for that. Any
advice?
-- Fran Fredricks, North Aurora
A. I
suggest you try an old-time TV antenna instead of waiting for a
costly HD cable box. You'll be surprised at how well plugging a
regular TV antenna into an HD receiver works.
HDTV may be the wave of the future, but its arrival comes with
maybe as much confusion as that which afflicted consumers back in
the early days of television when we watched broadcast shows with
rabbit
ears in the city and rooftop TV antennas in the suburbs.
Few folks seem to know that because HD receivers are digital
devices rather than analog machines, they work far better than
ordinary TV sets using ordinary antennas for broadcast television.
With digital broadcasts there can be no snow, no double vision
because of nearby buildings and other bad reception. If you are in
range of the HD signals broadcast in major cities, then they will
either come in clear or not at all. It's almost amazing to see the
ultra ultraclarity of an HD show and realize it's coming through
your rabbit ears.
Figure on approximately 20 channels of digital reception,
including most of the large networks' prime-time broadcasts, as
well as PBS shows and smaller outlets such as UPN and PAX.
The consumer electronics industry is Johnny on the Spot with HD
help, including a Web service (www.antennaweb.org) that
lets you plug in your address and see what sort of antenna might be
needed. Another Web site, www.checkhd.com, offers grid
schedules of shows available to you.
All you need to do is use one of the auxiliary video source
connectors on your new big screen for an over-the-air antenna.
_______________________________________________________________________________________________________
Just put up a TV
antenna
Posted by petealicat - August 6, 2005 7:04 PM
PDT
We just put up our TV antenna and cancelled cable. How liberating!
Kids will be smarter, we have more family time, we save
money...it's all good
_______________________________________________________________________________________________________
How to Make a TV Antenna on a Budget
This guide will show you how to make a TV antenna with a
fruit or vegetable and a cable cord.
Steps
Purchase a fruit or vegetable. Oranges tend to last the longest and
potatoes work well too.
Buy a cable cord.
Attach the cable cord to the fruit or vegetable(the pin inside the
tip of the cord is the only part that should be pressed into the
fruit or vegetable.)
Take a piece of electrical tape or similar and tape the cord onto
the fruit or vegetable so it does not become dislodged.
Plug the other end of the cable cord into the back of your
television.
Things You'll Need
Fruit or vegetable (an orange or potato)
A common cable cord
Electrical tape
_______________________________________________________________________________________________________
The fuzz-free TV antenna
12/26/05
Few people know they can get extra-sharp digital broadcast
television signals with an old-fashioned antenna, on which millions
of American homes still depend for free TV. All that's required is
an external box called a digital tuner (starting at about $150)
that decodes the new signals simulcast now by most stations, and
it's easy to connect. The digital signals arrive crystal clear,
with no fuzzy or ghosted images. Beginning next spring, the digital
tuners will be built into most new sets as Congress pushes us
toward all-digital TV. Already, RCA sells a 27-inch standard model
TV with a built-in digital tuner for about $300.
The digital broadcasts aren't as sharp as luxurious HDTV, but
they do offer a DVD-caliber picture. And there's another bonus:
Local stations can broadcast several digital channels. My local PBS
station has three, including one with all-day kids programming
that, by the way, isn't available on cable or satellite. -David
LaGesse
Go to HDTV In THe News page two
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