DTV, ATV AND HDTV IN THE UNITED STATES

A Summary As Of March 2007

HD & DTV, WHAT DO THEY MEAN?

The term “DTV” refers to a digital terrestrial transmission system designed to carry television signals to consumers’ homes as digital bit streams rather than as analog waves.  This is the strict definition of DTV.  The term, however, is frequently being used in marketing activities to describe anything and everything in the emerging world of consumer and professional digital and HDTV television.

The DTV system chosen for broadcast in the US is known as Advanced Television Systems Committee (ATSC) system.  The ATSC is the committee that codified the standards settled upon by a “Grand Alliance” of electronics organizations and manufacturers.  Television stations in the 20 largest markets began broadcasting the ATSC digital signal on December 1, 1998.  Presently there are more than 1500 stations in all but one of the US markets broadcasting in DTV, though in some smaller markets the choice between digital stations can be extremely limited.  Cable and satellite subscribers have quite a few more choices as each typically have digital packages, many of which carry high-definition programming.

You may also be wondering how long you’ll be able to keep watching your old TVs.  Broadcasters had originally been ordered to turn off their analog broadcasts in 2006, but late in 2005 the Federal Communications Commission (FCC) extended the deadline until February 19, 2009.  This gives you a few more years to upgrade your equipment.

If you’re wondering if you need to buy a new TV before 2009, the answer is “no”.  While current televisions cannot recognize a digital signal, consumers will be able to purchase set-top converters that will receive the digital signals being broadcast and convert them into the analog signals that their TVs can accept.  Keep in mind, however, that people with the digital-to-analog converter box will not be watching true HDTV.  The set-top box will “down-convert” the digital signals to analog, offering the same resolution of current standard-definition broadcasts.  It is estimated these boxes will cost between $50 and $75 each, though the federal government will provide up to two $40 coupons per household for the converters.

PICTURE

To receive the full high-definition picture, viewers will need a high-definition television.  High-definition television, or HDTV, delivers a far superior picture to current standard-definition television (SDTV).  Where on SDTV a front lawn appears as a solid mass of green, on HDTV individual blades of grass appear.  Cigarette smoke transforms from a gray smear into swirling, intricate patterns.  A football in flight becomes so clear in HDTV that viewers can clearly see the seams as it spirals down the field.  And every line on an actor’s face becomes visible as he or she projects.

Pictures on HDTV sets are not only much clearer, they are also wider than those currently being broadcast.  SDTV pictures have an aspect ration of 4:3; that is to say the picture (and screen) is four units wide and three units tall.  HDTV on the other hand displays a 16:9 picture.  The advantage may not be immediately apparent, but consider the shows that are broadcast in widescreen at the moment.  Most of the major networks’ prime time line up is filmed in the 16:9 format.  If you have a modern SDTV, this means that you either have black bars at the top and bottom of the screen or you’re missing the far left and right portions of the picture.  In the aforementioned football game, the viewer will see about 20 yards more of the field.

Another consideration in HDTV is the format in which it is being broadcast.  Formats fall into two basic categories: interlaced scanning and progressive scanning.  If you look closely enough at your TV, you’ll see a series of tiny horizontal lines.  Each of these lines is made up of dots called pixels.  An electron gun inside the TV paints the horizontal lines one by one 30 times per second.  A regular picture tube can have as many as 520 lines, but most screens only display 432 or fewer.  Because analog TV channels aren’t large enough to carry the entire picture frame, each frame is sent in two halves. 

Interlacing is the process of assembling a picture on your screen in halves.  If you hold your hands in front of your face and weave your fingers together, that is what your TV picture looks like. The odd-numbered lines are painted first, then the even numbered lines.  Each half takes 1/60^th of a second to be painted—so fast that it looks like a single picture.  But because the two halves are trying to match up as one image, there is inevitably some mismatch that reveals itself as a flicker or blur.  The FCC classifies 18 different formats as DTV.  Standard-definition television (SDTV) is what most consumers presently receive.  Even viewers who have cable with a digital package are watching standard definition.

There is still some question as to what format of DTV will be broadcast, but for the most part, networks have backed their own respective systems.  The FCC classifies HD as resolution of 720p Progressive scanning or better.  Now that FOX has abandoned their 480p, or enhanced-definition broadcasts, the major networks all broadcast their HDTV signal in either 720p or 1080i.

There is some debate as to which is the better format of high-definition, 720p or 1080i.  The answer depends on whom you ask and what you’re watching.  Networks airing lots of sports programming tend towards 720p as the progressive scanning displays motion more clearly.  Networks that have fewer hours of sports or live-action programming tend towards the 1080i as the greater number of lines available display still-shots clearly and with slightly better detail than 720p despite the interlacing. 

SOUND

The absorbing high-definition pictures will be accompanied by six channels of Dolby digital sound, making it possible to set up left, right and center speakers in the front of the living room, two surround-sound speakers in the back and a subwoofer under the couch.  Bullets and spaceships will be heard whistling overhead, just like at the movie theater.  A televised concert with music by Mozart or the Mighty Mighty Bosstones will get your neighbor’s attention.

Dolby Digital 5.1 surround sound is supported by HDTV, giving users the opportunity to set up a six-speaker surround sound system, a la movie theaters.  The sound gets divided between three front channels, left, center and right, two rear or side channels and one “Low Frequency Effects” channel, which can be utilized by a subwoofer.  All of this enhances your viewing enjoyment by immersing you more fully into the experience.

PRICE

The price of HDTV is still comparatively high to that of SDTV, but the difference is not nearly as great now as when HDTV sets were first introduced.  CRT high-definition sets start in the $700 to $800 range, though at that price you need to be sure that the set display is in true HD.  Many TVs advertised as HD or HD-Ready only display 480p resolution.  This is an upgrade from the current 480i of SD, but it is not truly high-definition.  HDTV resolution starts at 720p.  Consumers looking for the flat-panel HDTV with a D-ILA, plasma, LCD or other similar display should be ready to spend well into the thousands.

You also have some choice in the type of set you can buy, though that choice is quickly dwindling.  There are two types of HDTV sets, those without an ATSC tuner and those with one.  Sets without tuners, or monitors as they are known, require the consumer to supply an outside or set-top receiver.  You may think it would be pointless to buy a monitor, but considering that most cable and satellite providers require their own set-top box in order to receive their digital and HD programming, you don’t need to buy your own HDTV with a tuner.  This could save you upwards of $100 on the cost of a new set.  At present, you should still be able to find HDTV-Ready monitors that don’t have tuners in just about all screen sizes.

Monitors will become scarce, however, in coming years as Congress, in an attempt to speed the adoption of the new format, has mandated a gradual phase-in of HDTVs manufactured with built-in tuners.  Thus the cost of the external tuner that used to be optional will soon be included in the price of TVs.

Another consideration is something that is talked about only in hushed tones: most networks air their daytime programming in 480p.  If you do most of your viewing during the daytime, or are planning on getting a smaller screen (27” or less), 480p may be something for you to consider.  The reason for this is that many people are unable to notice the difference between 480p and higher resolutions on a screen that size.  Thus if you’re purchasing a smaller set, you may be able to save some money by going 480p.  Remember, though, this does not work for larger TVs, so the bigger the screen, the better the resolution you’ll want.

THE DIGITAL LANDSCAPE

As of March 2006, all but one market have at least one station broadcasting digitally over the air.  So you can receive DTV over the air with the proper receiver and monitor.  Since local stations broadcasting over the air broadcast analog and digital signals, the numbering can be a little foreign.  For example, WEDU Channel 3 in Tampa actually broadcasts three different channels.  These are noted as channels 3-1, 3-2 and 3-5, each one carrying a different signal.

As noted above, most cable and satellite providers also offer HD packages.  Your provider will also rent a set-top tuner that will allow you to receive both the cable broadcasts and whatever HD programming they offer.  Cable networks such as ESPN and HBO, along with many others, offer HD versions of their programming, giving you many more hours per week of choices than standard over-the-air networks offer. 

Another consideration is that most cable and satellite operators offer the national feed for the major broadcast networks.  This may not be a big deal to people living in the major markets, but for people in smaller markets where the affiliates are not yet carrying the HD signal, the cable/satellite option means they’ll be able to view their favorite primetime programs in HD for the first time.

WHAT IT ALL MEANS

In the end, DTV’s future is becoming clearer by the day.  The end of analog broadcasting is around the corner.  TV manufacturers are working to bring new and exciting products to the market to allow consumers to enjoy the new content being broadcast every day.  And everyday, the new technologies are becoming more and more affordable, making HDTV a reality for more homes all the time.

Televisions aren’t the only home electronics that will be affected.  DVD players that play movies in high-definition will soon be available, though there will be two competing formats, HD DVD and Blu-ray.  New HD Digital Video Recorders, or DVRs, are also presently available, allowing viewers to capture high-definition programming on a hard drive, much like many already do with TiVo and other devices.  And just as with the cost of HDTV sets, the price tags on these other items will be falling as the changeover approaches.

Clearly, DTV and HDTV are on their way and the closer we get to the analog cut-off date, the more choices consumers will have when it comes to enhancing their viewing experience.  And the best is yet to come.  As we get closer to the changeover to DTV and HDTV, consumers will have more options to choose from in the way of programming and how they can view it.  The next few years will be a very exciting time for home theater enthusiasts and casual viewers alike.

But you don’t have to wait.  Broadcast networks’ prime time lineups already offer a great selection of shows in HD and cable and satellite companies offer many attractive packages replete with sports programming and movie channels.  Now is your chance to be the first on your block to enjoy the awe-inspiring picture and surround sound delivered by the High-Definition format.

Note: Material and information for this section gathered from U. S. NEWS & WORLD REPORT, The San Francisco Chronicle, JVC Professional Video, National Association of Broadcasters, the Federal Communication Commision and Media Concepts’ Research Department.

WHAT IS DTV?

"DTV" is a single, serial stream of digital bits representing one, or a combination of, television program(s), audio program(s), data service(s) and a potential wide variety of other information, transmitted to receiver/decoders in consumer homes. Some of the technical characteristics of a transmitted "DTV" bit stream are as follows:

Principal technologies employed in the ATSC Standard for the transmitted digital "DTV" bit stream:

Video Compression       MPEG-2 Main Profile at Main Level (MP @ ML) or Main Profile at High Level   (encoding)                     (MP @ HL).

Audio Compression       Dolby AC-3 system (encoding)

Digital Modulation          8 VSB system

Features of the technologies used in the ATSC Standard:

8 VSB Modulation         Digital bit stream transmission modulation that permits a maximum transmitted bit rate of about 20 Mb/s within a bandwidth of 6 MHz.  6MHz is the channel width occupied by current analog NTSC television signals.

MPEG-2                         Input video is component; Y, CR, CB.  Image sampling structure is 4:2:0. Output is MPEG-2 (MP @ ML, 15Mb/s maximum) for 525/60.  Users can select any bit rate below 15 Mb/s. Output is MPEG-2 (MP @ HL, 80Mb/s maximum) for HDTV.  Users must select any bit rate below ~ 20Mb/s.

Dolby AC-3                    Compressed digital audio bit stream representing 5.1 channels of High Fidelity Surround Sound.

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