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- Dec 06, 2007
Learn how to shop for a new high-definition TV, and get the features you want for your budget and viewing style. Seattle journalist Clark Humphrey helps you sort through the jargon, understand the technology, consider a variety of peripherals, set up your new system, and find HDTV programming.
"I think everyone who walks into the media section of Best Buy, Circuit City,
Wal-Mart, etc. should be given a copy of this book." -Kathy Berndt
Updates and this ebook: Because the world of digital TV is changing rapidly, we’ve found it difficult to keep this PDF updated, and we do not plan to update it again.
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Clark also looks at how to bring your computer into your TV-viewing system, with notes on video-download sites and products such as the Apple TV and Elgato’s EyeTV line. Case studies show how two technology writers have set up tech-laden TV-viewing systems in their homes, and a third case study highlights the importance of paying attention to the fine-print in a return policy.
Read this book to learn the answers to questions such as:
- Which is best - DTV, SDTV, EDTV, or HDTV?
- Do I want 480i, 480p, 720p, 1080i, or 1080p?
- Is a flat-screen TV better than a tube? What about projection sets?
- Given a choice between LCD and plasma flat screens, which should I choose?
- How far away from my large-screen TV should I sit for optimal viewing?
- Where is the best place to buy a digital TV?
- What features should I look for in a DVD player?
- Where can I find more HDTV programming?
- What’s it like to use an Apple TV? Where are good sites for downloading video from the Internet?
This book covers digital TV from the North American perspective; standards and formats differ in other parts of the world.
What geographical regions are covered in this title?
This book covers digital TV from the North American perspective; standards and formats differ in other parts of the world.
- Read an Excerpt!
This excerpt discusses the history of TV technologies and helps you understand the different technologies available and why North America is currently undergoing a switch from analog to digital TV.
The Past: Analog
Television’s original developers and regulators did their best to give us a simple, easy-to-use technology, given the primitive tools and mechanisms then at hand. The ability to send moving pictures through the air in real time was one miracle; making their reception easy enough for the average family was another.
Regularly scheduled telecasts began in the United States in 1939 (3 years after they’d begun in Britain). The first Canadian stations launched in 1952; by then, many Canadians could already receive northern U.S. stations.
The National Television System Committee (NTSC), made up of corporate and governmental representatives, devised the transmission standards for North American TV. They included 525 horizontal lines (including 480 devoted to the picture), at 60 interlaced fields or half-frames (for 30 total frames) of black-and-white pictures per second, transmitted on 6 MHz channels, with frequency-modulated (FM) audio.
In the early 1950s, a second NTSC was formed to add color information to the signals. The committee chose RCA’s “compatible” color scheme, which enabled existing black-and-white TV sets to receive monochrome versions of color transmissions. It did this by adding a color signal (known as chrominance) to the existing brightness signal (known as luminance). For more than 4 decades, all video innovations (videotape, camcorders, cable, VCRs, and transistor- and chip-based equipment) sold in the United States and Canada would be made to NTSC specifications. By the mid-1980s, the NTSC phased in stereo sound and closed captioning (optional subtitles for the hearing impaired, as described at http://en.wikipedia.org/wiki/Closed_captioning). They were the last major additions to NTSC analog TV.
“NEVER THE SAME COLOR”
Videophiles have long derided the NTSC color standard, giving it such pejoratives as “never the same color.” Until recently, when their TV-set technology advanced to include color-stabilization, American viewers had relatively fuzzy pictures and wandering color hues, while European viewers enjoyed sharper pictures with higher resolution and more stable colors. European countries didn’t switch to color until the 1960s. When they did, they picked newer, more advanced standards–either PAL (phase alternating line), developed in Germany, or SECAM (sequentiel couleur avec memoire, or sequential color with memory), developed in France. These standards were not only incompatible with the NTSC system but also with their own countries’ black-and-white telecasts.
For several years, Europe’s broadcasters would simulcast (simultaneously broadcast) the same shows on separate color and black-and-white channels, before they finally shut off the black-and-white channels. (For example, the British Broadcasting Corporation launched color channels in 1967 and scrapped the last black-and-white channel in 1985.) Now, the United States and Canada are going through a similar transition from analog to digital TV.
The Present (and Near Present): The Digital Transition
HDTV and digital video began as separate technologies, before they merged to form the basis of today’s video revolution.
HDTV, also known as high-definition television, emerged in the early 1980s as an experimental Japanese analog system. (Japan’s big public TV network, NHK, had begun research and development for it as far back as 1963.) It offered near-theater-quality pictures and surround sound, but it required too much bandwidth to be transmitted on standard TV channels. NHK marketed its analog HDTV worldwide under the names Hi-Vision and MUSE (Multiple Sub-Nyquist Sampling Encoding), but it never spread commercially beyond Japan.
The Federal Communications Commission (FCC) rejected NHK’s analog HDTV for use in the United States, because it required 9 MHz of broadcast bandwidth, one and a half times that of standard U.S. TV channels. In addition, the FCC felt political pressure to nurture a homegrown advanced-TV system, hoping to stem Japan’s dominance of the video-hardware industry.
If you live in Canada, you might wonder how the Canadian Radio-television and Telecommunications Commission (CRTC) fits into this discussion. As it turns out, the CRTC has nearly always followed the technical standards adopted by the FCC in the United States.
In 1982, the Advanced Television Systems Committee (ATSC), was formed by several industry and professional associations (including the National Association of Broadcasters, the National Cable Television Association, and the Society of Motion Picture and Television Engineers, among others). As the committee’s name (based on the old NTSC) implies, the group would spearhead private-sector efforts to create a new way to make, send, and receive TV signals. In 1987, the FCC formed the Advisory Committee on Advanced Television Service to oversee the government’s side of advancing TV. Initially, it rejected several proposals for enhanced analog TV systems. None of them provided enough improvement over traditional NTSC signals within the bandwidth of a standard TV channel.
Then came digital.
Analog video uses a continuous, variable electrical signal. Digital video, in contrast, uses a sequence of discrete binary digits, the same 1s and 0s that are the building blocks of personal computing. These digits are used to form pixels (picture elements), tiny squares or rectangles of color just like those on your computer monitor.
Digital video images weren’t intrinsically superior to analog video images. But they provided an opportunity to move beyond the NTSC’s primitive color encoding. They could be copied and retransmitted with no degradation in image quality. And, more importantly, digital signals could be compressed, by replacing redundant information with mathematical algorithms.
In the late 1980s and early 1990s, digital video surfaced on two fronts. First, on the professional end, lightweight chip-based cameras and tapeless editing systems began to appear. These eventually revolutionized video production (and made today’s nonstop news channels and reality shows more feasible). Second, in the mid-1990s, compressed video formats (such as Apple’s QuickTime, RealNetworks’ RealVideo, and Microsoft’s Windows Media) brought small-screen-size video clips to computer desktops around the world.
Because few Internet users had broadband connections back then, image compression was incorporated in every online-video standard. Some compression schemes and algorithms were developed in-house by Apple, RealNetworks, Microsoft, and others. Some were licensed from outside developers.
In addition to these proprietary systems (controlled by a single company), other digital video standards have become available for license to the industry as a whole. The most prominent of these is the MPEG series of specifications (named for the Moving Picture Experts Group, the international consortium that originally worked them out). (The audio-compression format known popularly as MP3 is a subset of the group’s earliest video format, MPEG-1.) The group’s MPEG-2 video standard has become a basic part of digital TV standards in the United States. (For the nitty-gritty on MPEG-2, see http://bmrc.berkeley.edu/frame/research/mpeg/.)
Thanks to digital compression, high-definition signals could at last fit into standard broadcast TV channels, with room for one or two standard-definition signals as well.
In 1990, General Instrument submitted a proposal to the FCC for an all-digital HDTV system. Soon after that, the FCC received similar proposals from Zenith, AT&T, and the Massachusetts Institute of Technology (MIT). Instead of accepting one of these systems as-is, the FCC asked the four organizations, plus three others (Philips, Thomson/RCA, and the David Sarnoff Research Center), to pool their research and form a single standard.
By 1994 this consortium, known as the Digital HDTV Grand Alliance, had developed an all-digital HDTV system that had more in common with computers than with traditional TV. The Grand Alliance’s specifi-cations were approved, with minor modifications, by the ATSC, and then, with other minor changes, by the FCC. (You can read a long version of this history at http://www.atsc.org/history.html.)
Beginning in late 1997, the FCC assigned an additional channel (typically in the UHF band) for each existing U.S. TV station to use for digital transmission. As of April 2007, 1,603 of the 1,725 U.S. TV stations simulcast in analog and digital. The remaining analog-only stragglers are expected to get their simulcast channels up and run-ning by the end of 2007. (In a handful of cases, the FCC has allowed a station to remain analog-only for now, as long as it promises to switch to digital later.)
The first digital simulcast channels signed on in November 1998. Each of these channels has 6 MHz of bandwidth, the exact same amount of bandwidth an old, analog NTSC channel used. Out of that band-width, 1 MHz is sufficient to send a digitized version of a station’s regular signal. An HDTV signal can fit into as little as 4 MHz. That leaves 1 MHz for stations to use for data transmission or an extra standard-definition TV (SDTV) channel. The major networks are now feeding multicast (multiple broadcasts on one frequency) digital channels to their affiliates, such as PBS Create and NBC Weather Plus.
Alternately, a station can multicast up to six standard-definition channels on its digital bandwidth. For example, Seattle’s PBS affiliate, KCTS, formerly offered three SDTV digital channels during the day (KCTS-DT, KCTS Learns, and KCTS Kids)–using 1 MHz per channel, or 3 MHz total, and then switched at 3 p.m. to one SDTV channel (KCTS-DT) and one HDTV channel (KCTS-HD)–using 5 MHz total, 1 MHz for SDTV and 4 MHz for HDTV. (As of early 2007, KCTS-HD went 24 hours.)
Digital cable and satellite TV
Around the same time in the 1990s that digital broadcasting began in the United States, cable systems began to add digital tiers of channels to their existing analog transmissions, as they replaced their coaxial lines with fiber optics. Now, many cable systems are dropping their legacy analog services, switching those channels to bandwidth-conserving digital versions. That lets the cable providers use the extra space for such things as more SDTV or HDTV channels, pay-per-view and on-demand content, and Internet and phone services.
In contrast to the cable companies, home satellite TV services, such as DirecTV and Dish Network, were all-digital from the start. They are phasing in MPEG-4 compression, a more robust system that fits DTV signals into an even smaller bandwidth than MPEG-2 allows (MPEG-4 was finalized in 1998, after digital-broadcast standards had already been set in the United States). MPEG-4 allows satellite companies to squeeze even more SDTV or HDTV channels onto their existing satellites, reducing (but not eliminating) their need to launch more hardware into the sky.
The Future: The Analog Shutoff
Eventually, the old analog transmitters will shut down, so the U.S. government can reassign some of the surplus frequencies to emergency communications services and resell the others to wireless phone and data companies, resulting in a one-time gain of up to $50 billion to the U.S. Department of the Treasury.
The U.S. Congress debated the shutoff date throughout 2005. In early 2006, Congress officially set February 17, 2009, as the date when analog TV transmissions will cease.
At that time, according to the FCC’s current plans, TV channels 52-69 will be reassigned to new uses. The DTV versions of current analog stations on channels 52-69 will move to new frequencies; other DTV stations will revert to their stations’ original channels.
Users who haven’t bought digital receivers before the analog shutoff can still use their old sets to watch cable or satellite signals, DVDs, and videotapes, and to play video games; but they’ll need a new external tuner to receive traditional over-the-air (OTA) TV stations. Under a federal subsidy program scheduled to launch on January 1, 2008, eligible U.S. households will be able to receive up to two $40 discount coupons for digital-TV tuner boxes.
To speed the transition, the FCC is requiring set makers to phase out analog-only receivers. In June 2005, it required set makers to provide at least standard-definition digital tuners in all big-screen TV sets (more than 36 inches, measured diagonally) and half of all midsize sets (25 to 36 inches). As of March 1, 2007, all TV receivers sold in the United States must include digital tuners. (Devices billed as “monitors,” however, needn’t include tuners; neither do receivers that made it into the retail-supply chain before the deadline.)
- Update Plans
December 2007—Because the world of digital TV is changing rapidly, we’ve found it difficult to keep this book updated, and we do not plan to update it again.
Posted by Adam S Khan
The current version of this ebook is 2.1, which includes a number of changes, including details about high-def cable and DirectTV channels; updated coverage of products from Elgato, Miglia, and Apple; and more. However, since we have no plans to release further updates to this ebook, we’re no longer charging an update fee; feel free to download the latest version (from December 2007) using the link in the Downloads tab (it claims it’s version 1.3; that’s a little white lie to fool our content management system).
Posted by Adam S Khan (Permalink)