Digital Television - 14 Questions about digital televisionKeywords - digital tv,digital television,digital |
DTV stands for digital television, which refers to any all-digital TV broadcast. HDTV stands for high-definition television, and refers to broadcasts that contain a high-quality picture and Dolby Digital surround sound. When the FCC (Federal Communications Commission) set out the rules and allocated the airspace for digital TV in late 1996, it decreed that all HDTV broadcasts in the United States would be digital.
That doesn't mean that all digital broadcasts are going to be high-definition. Other possibilities include splitting one old analog TV channel into several standard-definition channels (SDTV multicasting) or sending a stream of data along with the program (enhanced TV or datacasting).
These options--or some unforeseen twist on them--could become the bread and butter of DTV. As if to confuse the issue, some commentators talk about ATV (advanced TV), generally meaning digital television and all its possible offshoots.
1. How many different HDTV formats are there?
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In the United States, there are 18 video formats for digital television.
However, only widescreen, high-resolution transmissions can truly be called
HDTV.
- 1080i = 1080 lines of resolution, interlaced
- 720p = 720, progressive
- and so forth.
Widescreen means an aspect ratio of 16:9, rather than today's 4:3. Resolution, however, is more complicated. It is measured in part by the number of horizontal lines in the picture, and in part by how the signal comes into your TV--all lines at once (progressive, like today's computer monitors), or every other line in two sweeps (interlaced, like today's TV screens). There's a common shorthand for talking about resolution:
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So far, the United States, Canada, South Korea, Taiwan, and Argentina
have agreed to use the formats and transmission methods recommended by
an industry group called the ATSC (Advanced Television Systems Committee).
European countries and Australia, however, plan to use a different system
called DVB-T (Digital Video Broadcasting-Terrestrial). The two kinds of
signals are transmitted and encoded differently, and cannot be received
on the same gear.
Japan has broadcast a completely different, analog version of HDTV since 1989. However, in 1997, the government decided to go digital. The Japanese system, slated for adoption by 2003, will be similar but not identical to DVB-T.
Some critics have claimed that the ATSC system has serious transmissionproblems, and that consumers will be unable to pick up the signals without investing in expensive extra equipment (Editor's note: InData Group has not tested these products, and cannot confirm whether this is a real problem). If this turns out to be the case, and it's not easily fixable, the United States and other countries could conceivably come around to some variation of DVB-T.
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Not necessarily. Several companies, including Panasonic, Sharp, and Sony,
are releasing set-top boxes that will make digital signals work on a standard
TV. Currently, these boxes are very expensive--from $1,500 to $2,000--and,
as with any first-generation version of a brand-new technology, they may
not even work perfectly.
It's a safe bet that converter boxes will become cheaper, better, and more common over the next few years--especially if the cable industry finally jumps on board the digital bandwagon. Nobody wants to see millions of viewers locked out of television simply because they can't afford an equipment upgrade.
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Not all companies use the same definition, but most of the industry agrees
that HDTVs should be able to receive and display all 18 digital TV formats
approved for broadcast in the United States. In addition, HDTV resolutions
will exceed 480 lines per inch and must have a widescreen aspect ratio.
Digital-ready TVs (sometimes called other names, such as HDTV-ready or HD-compatible) do not receive digital signals--they have no built-in decoder. Instead, they have some sort of input so that, eventually, you'll be able to get a separate decoder box, hook it to your set, and have the equivalent of HDTV. The inputs vary from company to company, so you might have to buy a decoder from the same company that made the TV itself.
Digital-ready sets are usually in a widescreen format, and they often use progressive scanning. They're almost always capable of displaying more lines of resolution than normal TVs, and some even have a line-doubler or another technology that makes analog TV signals, VCR tapes, and DVDs look a lot better. Before you buy a digital-ready TV, be sure it's loaded--they're almost as expensive as full HDTVs, and you'll have to spend extra money for a decoder when you do want to receive digital broadcasts!
Both plasma and LCD flat screens display a picture on a screen. They have higher resolutions and richer color than many regular cathode-ray sets, and it doesn't take up much space. Flat screens are extremely thin and futuristic-looking--and expensive. Flat TVs are technically not HDTVs unless they have a built-in digital decoder designed to diplay high definition.
There are differeences between plasma and LCD screens as this article will detail.
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Yes. Consumers would be pretty angry if they bought an $8,000 TV, only
to find that it didn't work with current technology. All the companies
we spoke with said that their HDTVs and digital-ready TVs would have composite
video inputs (for peripherals) and antenna inputs (for receiving analog
TV signals). In addition, most HDTVs and digital-ready TVs will accept
the signals from peripherals and analog TV and actually increase their
resolution by doubling the number of lines or changing the scanning from
interlacing to progressive.
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Yes, as long as you have the right gear. Some high-res sets will have
an S-Video input, so if your computer's video card has an S-Video out,
you're in luck. Sharp has even announced a digital-ready set, the XV-ZW99,
that can work with the more traditional VGA outs.
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That depends on whom you ask. According to the Consumer Electronics Manufacturers'
Association, any so-called HDTV or digital TV decoder must be capable
of receiving all 18 digital TV formats approved in the United States,
and should be good as long as the FCC continues to require U.S. broadcasters
to use one of those formats.
But skeptics point out that public tests of HDTV gear have been very rare. James Burger is an attorney with clients in the electronics, cable, and computing industries who has been following the development of digital TV for more than ten years; he claims that today's HDTV gear may not even be able to receive digital broadcasts. According to some early tests, consumers would need to point a 30-foot antenna directly toward the nearest digital transmitter just to get the signals! (Editor's note: InData Group has not yet been able to test any DTV equipment in order to confirm this.)
More to the point, it's not clear which of the 18 digital TV formats will eventually become the most common standard. You might pay big bucks for a TV capable of displaying 1080 interlaced lines, only to find that broadcasters are going to stick with the 480-line progressive scan format, which takes up much less bandwidth--and which could come across perfectly well on your PC. We suggest that you wait for more public tests and better-defined industry standards before investing a lot of money in new gear.
The FCC has mandated by May 2009, all network affiliates will begin sending digital signals. Even so, HDTV is very expensive to produce, and the networks have only agreed to about five hours of programming per week.
High-definition television, one of several different formats that can be transmitted over DTV, uses one of two formats: 1280 × 720 pixels in progressive scan mode (abbreviated 720p) or 1920 × 1080 pixels in interlace mode (abbreviated 1080i). Each of these utilizes a 16:9 aspect ratio. (Some televisions are capable of receiving an HD resolution of 1920 × 1080 at a 60 Hz progressive scan frame rate — known as 1080p60, but this standard is not currently used for transmission.) HDTV cannot be transmitted over current analog channels.
More ominously, some critics claim that receiving over-the-air signals is extremely difficult without a large antenna aimed directly at a local DTV transmitter. And local broadcasters are running into stumbling blocks: it's difficult to find land for new digital transmitters (especially when residents complain about the huge antennae), and it has proven difficult to broadcast in Dolby Digital sound with today's equipment. Expect the deadlines to slip, and don't look for a huge amount of over-the-air HDTV programming over the next couple years.
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Yes and very well. Satellite was slightly ahead of the curve but CATV has done a good job of catching up.
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Yes, DTV tuner cards are available for PCs. Then again, that's for broadcast TV. You can of course receive streamed video over the Internet. That's like YouTube and such but there is network broadcast TV being streamed over the Internet as well. Because it's digital, you can watch it on a computer monitor, flat screen, iPhone, Blackberry, G-Phone - just about anywhere.
In some ways, your PC is the most logical place for digital TV. Computer monitors already use progressive scanning, and it would be much easier to upgrade a PC to receive extra data or other material than it would be to upgrade the brains of a new TV set.
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Probably. Digital signals can carry far more information than the current
analog signals, which makes them perfectly suited for the high-bandwidth
requirements of HDTV. However, the FCC left the door open fo broadcasters
to carry signals at lower resolution as well. Because there's so much
extra space with digital TV, it's possible for one local network affiliate
to split off into four separate standard-definition channels (this is
called SDTV multicasting), or some combination such as one HDTV channel
and two standard channels. If consumer demand for high-definition pictures
never takes off, it's far more likely that broadcasters will use their
bandwidth to show multiple channels.
13. Will digital TV give me data in addition to a regular picture?
There's been lots of speculation that some broadcasters or media companies will use the extra digital bandwidth to send a stream of data--such as sports statistics, movie star biographies, or Web links--along with images and sound. This twist on digital TV is called enhanced TV or, sometimes, datacasting.
In fact, it's already possible to do this with analog TV. In 1996, Intel began promoting a technology called Intercast, which allows PC users to receive regular TV signals along with Web-style data (the data is transferred in an unused portion of the analog signal called the vertical blanking interval). Consumers' and broadcasters' response to Intercast ranged from lackluster to nonexistent. Nonetheless, Intel has announced that they'll continue working on datacasting products--this time, tying them to DTV. So, it's a safe bet that sometime down the road, your PC will be able to receive a whole stream of data along with digital television broadcasts. Stay tuned.
14. What is personalized TV, or "smart TV"?
The TiVo and Replay receivers allow users to record shows, then play them back in whatever order desired. Viewers can even pause a live show in the middle of the broadcast, and the box will record the rest of the show for later viewing.
Yes, it's related to TV. Yes, it uses digital technology. And, yes, it's contained in a set-top box. But personalized TV really has nothing to do with what is usually called digital TV.
