The Picture Clears Up

DIGITAL TELEVISION

THE PICTURE CLEARS UP
What You Need to Know to Watch DTV or HDTV

by Peter H. Putman, CTS

The introduction of digital television (DTV) services in the United States has been fraught with missteps, bumps, and false starts since 1997. One of the big reasons why is the slow acceptance of DTV by the general public, who view often DTV as something happening in a parallel universe!

The vast majority of DTV broadcasts are only available as terrestrial signals, and information about scheduled DTV broadcasts is hard to find. Only a select few viewers can get the signals over cable, and the satellite offerings are limited to a couple of premium channels. DTV stations are slow to get on the air, and when they do, they are often running far less than their authorized power levels.

To add to the confusion, there are a plethora of TV sets being advertised for sale that are supposedly "DTV capable", "DTV-ready" and even "HDTV-ready". Instead of a small yellow RCA plug for video, we now have to deal with three wires colored green, blue, and red. Unless of course we happen to be looking at DTV set-top boxes (STBs) and TV sets that use the computer-standard 15-pin VGA connectors.

If it weren't for the explosive sales of DVD players, DTV might very well be dead in the water. No one can account for the phenomenal sales of DVD players, but there's no question they are currently the "hot" consumer video technology.

Thanks to DVD, the average consumer has learned about and now understands such arcane concepts as progressive-scan video, component video connections, widescreen anamorphic video, and Dolby surround audio. Guess what? Those are all building blocks of the new DTV standard.

It's not as difficult as you might think to watch DTV signals. If you happen to live in one of the top 30 TV markets, you probably have at least one DTV station on-air, and more likely have two or three. DTV broadcasts are sharing the same VHF and UHF TV spectrum as analog broadcasts, and in some cases channels within the same city are adjacent to each other.

Right now, the majority of DTV stations are broadcasting in the UHF (500 - 800 MHz) band, and it will remain that way once DTV is fully implemented (supposedly by January 1, 2006, but don't hold your breath!). There are selected allocations in the VHF band, and some stations are already negotiating with the FCC to retain their old VHF channels after the analog-to-digital changeover.

So - what TV sets are available to watch DTV and HDTV signals? Before we get into that, let's review some of the DTV "basics".

DTV 101

The new digital television standards in the United States encompass a wide variety of digital signals. You've probably heard about the 18 different Advanced Television Standards Committee (ATSC) broadcast formats, but in reality there are just four - interlaced 4:3 video with 480 scan lines (480i), progressive-scan video with 480 scan lines (480p), progressive-scan video with 720 scan lines (720p), and interlaced video with 1080 scan lines (1080i).

The first two formats - 480i and 480p - are considered Standard Definition Television (SDTV) as they don't offer any more picture detail than we can get now with our analog 525-line system. The next two formats - 720p and 1080i - are considered High Definition Television, as they deliver much more picture detail than currently available. 720p and 1080i are also 16:9 widescreen formats. (It's possible to transmit 480i and 480p 16:9 formats, but these remain SDTV in any case.)

The number "18" in the ATSC Table 3 standards is derived from different vertical refresh rates as well as square and non-square pixel formats. For home reception, the standards you'll encounter will be 1080i/30 (1080 interlaced lines, 30 Hz refresh rate), 720p/60 (720 progressive lines, 60 Hz refresh), 480p (480 progressive lines with either 60 Hz or 30 Hz refresh), and 480i (480 interlaced lines with 30 Hz refresh).

These signals are all transmitted as compressed 4:2:0 MPEG-2 streams, complete with audio and Program and Station Information Protocol (PSIP) data. This stream of data is modulated onto a radio frequency carrier using what's called the Eight Level Vestigial Sideband (8VSB) system, which cannot be received by a standard TV set. The maximum permissible data rate is 19.39 Mb/s, so as to fit within our legacy 6 MHz TV channels.

To receive and decode 8VSB signals, you'll need at the minimum a ATSC-compliant DTV set-top box. This device connects to your antenna (or cable, if you have 6 MHz DTV channels available that way) and decodes the digital information, splitting it into video, audio, and available data streams. (An integrated DTV set will have this tuner and perform the same functions.)

Even though DTV signals are 100% digital, the video and audio are usually fed as analog signals from the set-top box (except for Dolby 5.1, which usually connects through optical or coaxial cables to your audio system). The DTV video format is ALWAYS component and NEVER composite or S-video.

The standard implementation is sync-on-green, usually labeled "YPbPr". In this system, the picture sync travels on the luminance or "Y" signal, and color information on the Pb and Pr color difference signals. In order to watch these SDTV and HDTV signals without any additional conversion, you'll need a monitor, TV set, or projector with broadband component video input jacks.

Even though YPbPr is the ATSC standard video format, some manufacturers have chosen to output their signals as RGBS or RGBHV, two formats that are closer to the computer display world than DTV. The advantage of this format is that you can often use a standard computer monitor to watch the signals. The disadvantage is that many consumer DTV sets won't support RGBS or RGBHV.

All set-top boxes output stereo audio, and also include a Dolby 5.1 connection. On the simplest level, all you need is to hook up the component cables and stereo audio through RCA jacks, and you can watch DTV and HDTV. How it will look is another matter, and that depends entirely on the type of monitor, TV set, or projector you select!

CONFUSION REIGNS SUPREME

Because there are so many ways to watch DTV signals, manufacturers were bringing products to market and labeling them with no regard to any acceptable standard. For example, a TV set with component inputs might be able to display interlaced DVDs, but not show any progressive-scan DTV signals.

Similarly, a portable projector with RGB inputs might have a horizontal scan rate fast enough to display a 720p or 1080i HDTV signal, but not size and position them correctly if they appear in the RGBS or RGBHV formats. So, the Consumer Electronics Association (CEA) released a new set of definitions in late August of last year to help consumers understand the differences between TV sets and monitors.

Special logos are to be placed on these products to help consumers quickly distinguish between a digital set that receives ATSC broadcasts, and a video monitor that requires a set-top ATSC tuner to decode the broadcasts. Here's how the definitions break down:

High-Definition Television (HDTV) defines a fully-integrated television receiver that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats. In addition, it will display 720p or 1080i active vertical scanning lines in a 16:9 aspect ratio. It must also receive and decode, or pass through for decoding, Dolby digital audio.

High-Definition Television (HDTV) Monitor is a direct-view or rear-projection monitor that can be connected to a DTV set-top box and will display 720p or 1080i active vertical scanning lines in a 16:9 aspect ratio. To meet the definition of HDTV, the monitor must have true vertical resolution to show at least 540 progressive or 810 interlaced picture lines.

High-Definition Television (HDTV) Tuner is an RF receiver that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats. It must output the 720p or 1080i/p formats with minimum active vertical scanning lines of 720p, 1080i, or higher. Additionally, it may output HDTV formats that are converted to other signal formats, with lower-resolution ATSC formats (480i and 480p) output at those levels. (The output can also be 100% digital at full resolution.) It must also receive and decode, or pass through for decoding, Dolby digital audio.

Enhanced-Definition Television (EDTV) is a fully integrated television receiver that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats. It must have enough active scanning lines to meet at least the 480 progressive (480p) standard or higher, but does not have to support the 16:9 HDTV aspect ratio. It must also receive and decode, or pass through for decoding, Dolby digital audio.

Enhanced-Definition Television (EDTV) Monitor is a direct-view or rear-projection monitor that can be connected to a DTV set-top box and will display at least 480p active vertical scanning lines, with no specified aspect ratio.

Enhanced-Definition Television (EDTV) Tuner is an RF receiver that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats. It must output the 720p or 1080i/p formats with a minimum of 480 progressive vertical scanning lines. Alternatively, the output can be a digital bitstream capable of delivering 480p, while 480i can be output at native resolution. It must also receive and decode, or pass through for decoding, Dolby digital audio.

Standard-Definition Television (SDTV) is a fully integrated television that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats to "produce a useable picture". It can have less active scanning lines than an EDTV set. No aspect ratio is specified, and it must receive at least an analog audio signal.

Standard-Definition Television (SDTV) Tuner is an RF receiver that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats. The output signal may be in the form of NTSC video, or S-video. It must also receive and decode, or pass through for decoding, Dolby digital audio.

HAVE IT YOUR WAY

As you can see, there are numerous ways you can watch DTV signals. The catch is when there's an HDTV broadcast, which by definition means a 16:9 720p or 1080i signal displayed at true resolution. The majority of TV sets, monitors, and front projectors available use 4:3 aspect ratios for imaging, so the image may appear letterboxed with black bars on top and bottom.

In reality, all you really need is a electronic display with the correct horizontal and vertical scan rates, plus component inputs, to watch DTV and HDTV signals. The DTV scan rates (31.5 KHz for 480p, 33.75 kHz for 1080i, and 45 kHz for 720p) are well within the range of most multiscan computer/video monitors.

The 1080i standard has a great deal of support from Japanese manufacturers, and even ultraportable LCD projectors will recognize and correctly present 1080i material in a letterbox format. Older monitors will also recognize this format - I use a somewhat-ancient NEC MultiSync XM29 at home as an "air check" monitor, and it automatically syncs up and sizes 1080i RGBHV signals.

The 720p standard is a little trickier, as it originated on these shores. Many monitors and projectors will not size this format correctly in RGBS/RGBHV mode, as they think it is either an SVGA or XGA computer source. Newer models are now including support for 720p, provided the signal is connected as three-wire YPbPr. Some plasma monitors are now available that are "format agnostic" - just tell them the image aspect ratio and select the appropriate component video format, and you are in business.

480p seems simple to handle with its 31.5 kHz scan rate, and it is when connected as a YPbPr signal. Unfortunately, many projectors and monitors assume this is a VGA signal when RGB connections are used. If the source material is 16:9, it may be compressed into a 4:3 "window" and you won't be able to re-size it. The widespread adoption of 480p DVDs is helping to correct this problem.

I use other displays to watch DTV signals. A Sony VPH-D50HTU 7" front projector (very format agnostic) can display any DTV signals in the correct aspect ratio, provided the projector is converged and set up correctly. Sony's VPL-VW10 HT LCD projector is another popular choice for DTV, as it has native 16:9 LCD panels (1366x768 pixels) and recognizes all ATSC formats as long as they are connected to YPbPr inputs.

I also use a Princeton AF3.0HD 32" 16:9 monitor to view HD material. This monitor supports all ATSC formats without conversion, and although it prefers them to be connected as YPbPr signals, it will correctly size and center DTV signals in the RGBS/RGBHV formats. The two Sony projectors and the Princeton monitor would quality as true HDTV displays, while the NEC monitor would be strictly EDTV.

PLAYING IT SAFE

Right now, there is still a considerable amount of debate over the DTV standard in this country. 8VSB has not proven as robust for indoor reception as originally expected, and some voices (led by Sinclair Broadcasting) are calling for the U.S. to adopt the European COFDM DVB standard. Obviously, the antennas and receivers have to be improved, and steps are being taken in that direction.

In the foreseeable future, 8VSB will be the DTV standard in this country. If you want to watch DTV signals, the most logical way to do it is to use a separate DTV set-top box and a compatible HDTV, EDTV, or SDTV monitor or projector. (Once the DTV signal is decoded from 8VSB or COFDM, the signal format is the same - YPbPr, or RGBHV.) The box can be upgraded or changed later without having to replace the TV.

At home, I use a pair of Panasonic first-generation STBs (TU-DST50 and TU-DST51) to watch DTV programs. Both decode and pass all ATSC signals at their native resolution, including 720p. (Many tuners do not pass 720p and instead up- or down-convert it to 480p or 1080i.) The output of both tuners is in the YPbPr format, and I use an Extron CVC-200 format converter to change the signal to RGBHV for the NEC MS29 monitor.

Many manufacturers are now selling (or getting ready to sell) DTV set-top boxes. The earliest models were terrestrial-only receivers (also cable), but all the new models (except one) are combination terrestrial/satellite receivers, which cuts down the risk of unsold inventory. RCA was the first to sell an integrated terrestrial/satellite receiver, the popular DTC-100. Even though it outputs RGB and converts all progressive-scan signals to 540p, this STB has sold more units than any other model to date.

As a result, new combo STBs are coming to market from Mitsubishi (SR-HD400 and SR-HD500), Panasonic (TU-HDS20), Sony (SAT-HD100), Zenith, Toshiba, Princeton (HDT-2000), and Samsung (SIR-S60), to name a few. Most are available for $1,000 or less. In addition, Samsung announced a new terrestrial-only STB for $699 (SIR-T150) at the recent Consumer Electronics Show.

You can also watch DTV on your PC, although the products to chose from are limited. Hauppauge Electronics has been shipping the WinTV-D Digital TV tuner PC card ($299) for some time now, which lets you watch all ATSC format signals simply by connecting an antenna. The catch is; the output signal is always 480p, although you do have selectable aspect ratios.

Another recent PC-DTV entry is the Hi-Pix PC-DTV card ($399), which also allows you to receive and watch ATSC-format signals on your computer. Unlike the WinTV-D card, this version outputs a higher-resolution signal and can record the MPEG-2 bitstream directly to your hard drive for later viewing.

The list of HDTV, EDTV, and SDTV TV sets and monitors is too big and detailed to include here. Both conventional and direct-view DTV TVs and monitors are available from Panasonic, Hitachi, Mitsubishi, Sony, Samsung, Zenith, Sampo, Konka, RCA, Princeton, Toshiba, Sharp, Pioneer, Philips, and JVC. Rear-projection sets (using tubes) can be had from Sharp, Panasonic, Mitsubishi, Sony, Pioneer, Samsung, Zenith, Hitachi, Runco, RCA, Philips, and Toshiba.

Want a flat-matrix screen? You can get plasma from Sony, Pioneer, Runco, Hitachi, Fujitsu, Philips, Panasonic, Sampo, Samsung, Sharp, Revox, and Zenith, to name a few. LCD monitors capable of SDTV, EDTV, and even HDTV display can be had from Samsung, Sampo, Zenith, Sharp, and Sanyo.

LCD rear-projection TVs are now sold by Sony, Samsung, JVC, and RCA, among others. Finally, Texas Instruments' DLP technology is now available in rear-projection TVs sold by Panasonic, Mitsubishi, and Hitachi, and front-projection versions were shown at CES by Toshiba, Sharp, and PLUS.

WHERE DO I START?

If you are ready to take the plunge into DTV, there are a few web sites with useful information to check out. Etown (www.etown.com) has a comprehensive list of products and reviews, plus a regular schedule of DTV and HDTV programming updated every ten days. CBS has its schedules available at http://www.cbs.com/hdtv/ , and PBS lists its schedule for the next few months at www.pbs.org/dtv.

Another good source for information is the AV Science web site at http://www.avsforum.com - but there are literally thousands of discussions going on about everything from set-top boxes to antennas, DSS reception, programs, and of course TVs, monitors, and projectors. I've posted several articles about terrestrial reception at http://www.projectorexpert.com which may be helpful if you need more information about signal reception.

Copyright ©2001 Peter H. Putman / Intertec Publishing
This article appears in the March 2001 issue of Video Systems.


						DIGITAL TELEVISION
					THE PICTURE CLEARS UP What You Need to Know to Watch DTV or HDTV


					by Peter H. Putman, CTS The introduction of digital television (DTV) services in the United States has been fraught with missteps, bumps, and false starts since 1997. One of the big reasons why is the slow acceptance of DTV by the general public, who view often DTV as something happening in a parallel universe! The vast majority of DTV broadcasts are only available as terrestrial signals, and information about scheduled DTV broadcasts is hard to find. Only a select few viewers can get the signals over cable, and the satellite offerings are limited to a couple of premium channels. DTV stations are slow to get on the air, and when they do, they are often running far less than their authorized power levels. To add to the confusion, there are a plethora of TV sets being advertised for sale that are supposedly "DTV capable", "DTV-ready" and even "HDTV-ready". Instead of a small yellow RCA plug for video, we now have to deal with three wires colored green, blue, and red. Unless of course we happen to be looking at DTV set-top boxes (STBs) and TV sets that use the computer-standard 15-pin VGA connectors. If it weren't for the explosive sales of DVD players, DTV might very well be dead in the water. No one can account for the phenomenal sales of DVD players, but there's no question they are currently the "hot" consumer video technology. Thanks to DVD, the average consumer has learned about and now understands such arcane concepts as progressive-scan video, component video connections, widescreen anamorphic video, and Dolby surround audio. Guess what? Those are all building blocks of the new DTV standard. It's not as difficult as you might think to watch DTV signals. If you happen to live in one of the top 30 TV markets, you probably have at least one DTV station on-air, and more likely have two or three. DTV broadcasts are sharing the same VHF and UHF TV spectrum as analog broadcasts, and in some cases channels within the same city are adjacent to each other. Right now, the majority of DTV stations are broadcasting in the UHF (500 - 800 MHz) band, and it will remain that way once DTV is fully implemented (supposedly by January 1, 2006, but don't hold your breath!). There are selected allocations in the VHF band, and some stations are already negotiating with the FCC to retain their old VHF channels after the analog-to-digital changeover. So - what TV sets are available to watch DTV and HDTV signals? Before we get into that, let's review some of the DTV "basics". DTV 101 The new digital television standards in the United States encompass a wide variety of digital signals. You've probably heard about the 18 different Advanced Television Standards Committee (ATSC) broadcast formats, but in reality there are just four - interlaced 4:3 video with 480 scan lines (480i), progressive-scan video with 480 scan lines (480p), progressive-scan video with 720 scan lines (720p), and interlaced video with 1080 scan lines (1080i). The first two formats - 480i and 480p - are considered Standard Definition Television (SDTV) as they don't offer any more picture detail than we can get now with our analog 525-line system. The next two formats - 720p and 1080i - are considered High Definition Television, as they deliver much more picture detail than currently available. 720p and 1080i are also 16:9 widescreen formats. (It's possible to transmit 480i and 480p 16:9 formats, but these remain SDTV in any case.) The number "18" in the ATSC Table 3 standards is derived from different vertical refresh rates as well as square and non-square pixel formats. For home reception, the standards you'll encounter will be 1080i/30 (1080 interlaced lines, 30 Hz refresh rate), 720p/60 (720 progressive lines, 60 Hz refresh), 480p (480 progressive lines with either 60 Hz or 30 Hz refresh), and 480i (480 interlaced lines with 30 Hz refresh). These signals are all transmitted as compressed 4:2:0 MPEG-2 streams, complete with audio and Program and Station Information Protocol (PSIP) data. This stream of data is modulated onto a radio frequency carrier using what's called the Eight Level Vestigial Sideband (8VSB) system, which cannot be received by a standard TV set. The maximum permissible data rate is 19.39 Mb/s, so as to fit within our legacy 6 MHz TV channels. To receive and decode 8VSB signals, you'll need at the minimum a ATSC-compliant DTV set-top box. This device connects to your antenna (or cable, if you have 6 MHz DTV channels available that way) and decodes the digital information, splitting it into video, audio, and available data streams. (An integrated DTV set will have this tuner and perform the same functions.) Even though DTV signals are 100% digital, the video and audio are usually fed as analog signals from the set-top box (except for Dolby 5.1, which usually connects through optical or coaxial cables to your audio system). The DTV video format is ALWAYS component and NEVER composite or S-video. The standard implementation is sync-on-green, usually labeled "YPbPr". In this system, the picture sync travels on the luminance or "Y" signal, and color information on the Pb and Pr color difference signals. In order to watch these SDTV and HDTV signals without any additional conversion, you'll need a monitor, TV set, or projector with broadband component video input jacks. Even though YPbPr is the ATSC standard video format, some manufacturers have chosen to output their signals as RGBS or RGBHV, two formats that are closer to the computer display world than DTV. The advantage of this format is that you can often use a standard computer monitor to watch the signals. The disadvantage is that many consumer DTV sets won't support RGBS or RGBHV. All set-top boxes output stereo audio, and also include a Dolby 5.1 connection. On the simplest level, all you need is to hook up the component cables and stereo audio through RCA jacks, and you can watch DTV and HDTV. How it will look is another matter, and that depends entirely on the type of monitor, TV set, or projector you select! CONFUSION REIGNS SUPREME Because there are so many ways to watch DTV signals, manufacturers were bringing products to market and labeling them with no regard to any acceptable standard. For example, a TV set with component inputs might be able to display interlaced DVDs, but not show any progressive-scan DTV signals. Similarly, a portable projector with RGB inputs might have a horizontal scan rate fast enough to display a 720p or 1080i HDTV signal, but not size and position them correctly if they appear in the RGBS or RGBHV formats. So, the Consumer Electronics Association (CEA) released a new set of definitions in late August of last year to help consumers understand the differences between TV sets and monitors. Special logos are to be placed on these products to help consumers quickly distinguish between a digital set that receives ATSC broadcasts, and a video monitor that requires a set-top ATSC tuner to decode the broadcasts. Here's how the definitions break down: High-Definition Television (HDTV) defines a fully-integrated television receiver that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats. In addition, it will display 720p or 1080i active vertical scanning lines in a 16:9 aspect ratio. It must also receive and decode, or pass through for decoding, Dolby digital audio. High-Definition Television (HDTV) Monitor is a direct-view or rear-projection monitor that can be connected to a DTV set-top box and will display 720p or 1080i active vertical scanning lines in a 16:9 aspect ratio. To meet the definition of HDTV, the monitor must have true vertical resolution to show at least 540 progressive or 810 interlaced picture lines. High-Definition Television (HDTV) Tuner is an RF receiver that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats. It must output the 720p or 1080i/p formats with minimum active vertical scanning lines of 720p, 1080i, or higher. Additionally, it may output HDTV formats that are converted to other signal formats, with lower-resolution ATSC formats (480i and 480p) output at those levels. (The output can also be 100% digital at full resolution.) It must also receive and decode, or pass through for decoding, Dolby digital audio. Enhanced-Definition Television (EDTV) is a fully integrated television receiver that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats. It must have enough active scanning lines to meet at least the 480 progressive (480p) standard or higher, but does not have to support the 16:9 HDTV aspect ratio. It must also receive and decode, or pass through for decoding, Dolby digital audio. Enhanced-Definition Television (EDTV) Monitor is a direct-view or rear-projection monitor that can be connected to a DTV set-top box and will display at least 480p active vertical scanning lines, with no specified aspect ratio. Enhanced-Definition Television (EDTV) Tuner is an RF receiver that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats. It must output the 720p or 1080i/p formats with a minimum of 480 progressive vertical scanning lines. Alternatively, the output can be a digital bitstream capable of delivering 480p, while 480i can be output at native resolution. It must also receive and decode, or pass through for decoding, Dolby digital audio. Standard-Definition Television (SDTV) is a fully integrated television that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats to "produce a useable picture". It can have less active scanning lines than an EDTV set. No aspect ratio is specified, and it must receive at least an analog audio signal. Standard-Definition Television (SDTV) Tuner is an RF receiver that will receive any and all ATSC terrestrial broadcasts, and will decode all of the ATSC Table 3 formats. The output signal may be in the form of NTSC video, or S-video. It must also receive and decode, or pass through for decoding, Dolby digital audio. HAVE IT YOUR WAY As you can see, there are numerous ways you can watch DTV signals. The catch is when there's an HDTV broadcast, which by definition means a 16:9 720p or 1080i signal displayed at true resolution. The majority of TV sets, monitors, and front projectors available use 4:3 aspect ratios for imaging, so the image may appear letterboxed with black bars on top and bottom. In reality, all you really need is a electronic display with the correct horizontal and vertical scan rates, plus component inputs, to watch DTV and HDTV signals. The DTV scan rates (31.5 KHz for 480p, 33.75 kHz for 1080i, and 45 kHz for 720p) are well within the range of most multiscan computer/video monitors. The 1080i standard has a great deal of support from Japanese manufacturers, and even ultraportable LCD projectors will recognize and correctly present 1080i material in a letterbox format. Older monitors will also recognize this format - I use a somewhat-ancient NEC MultiSync XM29 at home as an "air check" monitor, and it automatically syncs up and sizes 1080i RGBHV signals. The 720p standard is a little trickier, as it originated on these shores. Many monitors and projectors will not size this format correctly in RGBS/RGBHV mode, as they think it is either an SVGA or XGA computer source. Newer models are now including support for 720p, provided the signal is connected as three-wire YPbPr. Some plasma monitors are now available that are "format agnostic" - just tell them the image aspect ratio and select the appropriate component video format, and you are in business. 480p seems simple to handle with its 31.5 kHz scan rate, and it is when connected as a YPbPr signal. Unfortunately, many projectors and monitors assume this is a VGA signal when RGB connections are used. If the source material is 16:9, it may be compressed into a 4:3 "window" and you won't be able to re-size it. The widespread adoption of 480p DVDs is helping to correct this problem. I use other displays to watch DTV signals. A Sony VPH-D50HTU 7" front projector (very format agnostic) can display any DTV signals in the correct aspect ratio, provided the projector is converged and set up correctly. Sony's VPL-VW10 HT LCD projector is another popular choice for DTV, as it has native 16:9 LCD panels (1366x768 pixels) and recognizes all ATSC formats as long as they are connected to YPbPr inputs. I also use a Princeton AF3.0HD 32" 16:9 monitor to view HD material. This monitor supports all ATSC formats without conversion, and although it prefers them to be connected as YPbPr signals, it will correctly size and center DTV signals in the RGBS/RGBHV formats. The two Sony projectors and the Princeton monitor would quality as true HDTV displays, while the NEC monitor would be strictly EDTV. PLAYING IT SAFE Right now, there is still a considerable amount of debate over the DTV standard in this country. 8VSB has not proven as robust for indoor reception as originally expected, and some voices (led by Sinclair Broadcasting) are calling for the U.S. to adopt the European COFDM DVB standard. Obviously, the antennas and receivers have to be improved, and steps are being taken in that direction. In the foreseeable future, 8VSB will be the DTV standard in this country. If you want to watch DTV signals, the most logical way to do it is to use a separate DTV set-top box and a compatible HDTV, EDTV, or SDTV monitor or projector. (Once the DTV signal is decoded from 8VSB or COFDM, the signal format is the same - YPbPr, or RGBHV.) The box can be upgraded or changed later without having to replace the TV. At home, I use a pair of Panasonic first-generation STBs (TU-DST50 and TU-DST51) to watch DTV programs. Both decode and pass all ATSC signals at their native resolution, including 720p. (Many tuners do not pass 720p and instead up- or down-convert it to 480p or 1080i.) The output of both tuners is in the YPbPr format, and I use an Extron CVC-200 format converter to change the signal to RGBHV for the NEC MS29 monitor. Many manufacturers are now selling (or getting ready to sell) DTV set-top boxes. The earliest models were terrestrial-only receivers (also cable), but all the new models (except one) are combination terrestrial/satellite receivers, which cuts down the risk of unsold inventory. RCA was the first to sell an integrated terrestrial/satellite receiver, the popular DTC-100. Even though it outputs RGB and converts all progressive-scan signals to 540p, this STB has sold more units than any other model to date. As a result, new combo STBs are coming to market from Mitsubishi (SR-HD400 and SR-HD500), Panasonic (TU-HDS20), Sony (SAT-HD100), Zenith, Toshiba, Princeton (HDT-2000), and Samsung (SIR-S60), to name a few. Most are available for $1,000 or less. In addition, Samsung announced a new terrestrial-only STB for $699 (SIR-T150) at the recent Consumer Electronics Show. You can also watch DTV on your PC, although the products to chose from are limited. Hauppauge Electronics has been shipping the WinTV-D Digital TV tuner PC card ($299) for some time now, which lets you watch all ATSC format signals simply by connecting an antenna. The catch is; the output signal is always 480p, although you do have selectable aspect ratios. Another recent PC-DTV entry is the Hi-Pix PC-DTV card ($399), which also allows you to receive and watch ATSC-format signals on your computer. Unlike the WinTV-D card, this version outputs a higher-resolution signal and can record the MPEG-2 bitstream directly to your hard drive for later viewing. The list of HDTV, EDTV, and SDTV TV sets and monitors is too big and detailed to include here. Both conventional and direct-view DTV TVs and monitors are available from Panasonic, Hitachi, Mitsubishi, Sony, Samsung, Zenith, Sampo, Konka, RCA, Princeton, Toshiba, Sharp, Pioneer, Philips, and JVC. Rear-projection sets (using tubes) can be had from Sharp, Panasonic, Mitsubishi, Sony, Pioneer, Samsung, Zenith, Hitachi, Runco, RCA, Philips, and Toshiba. Want a flat-matrix screen? You can get plasma from Sony, Pioneer, Runco, Hitachi, Fujitsu, Philips, Panasonic, Sampo, Samsung, Sharp, Revox, and Zenith, to name a few. LCD monitors capable of SDTV, EDTV, and even HDTV display can be had from Samsung, Sampo, Zenith, Sharp, and Sanyo. LCD rear-projection TVs are now sold by Sony, Samsung, JVC, and RCA, among others. Finally, Texas Instruments' DLP technology is now available in rear-projection TVs sold by Panasonic, Mitsubishi, and Hitachi, and front-projection versions were shown at CES by Toshiba, Sharp, and PLUS. WHERE DO I START? If you are ready to take the plunge into DTV, there are a few web sites with useful information to check out. Etown (www.etown.com) has a comprehensive list of products and reviews, plus a regular schedule of DTV and HDTV programming updated every ten days. CBS has its schedules available at http://www.cbs.com/hdtv/ , and PBS lists its schedule for the next few months at www.pbs.org/dtv. Another good source for information is the AV Science web site at http://www.avsforum.com - but there are literally thousands of discussions going on about everything from set-top boxes to antennas, DSS reception, programs, and of course TVs, monitors, and projectors. I've posted several articles about terrestrial reception at http://www.projectorexpert.com which may be helpful if you need more information about signal reception. Copyright ©2001 Peter H. Putman / Intertec Publishing This article appears in the March 2001 issue of Video Systems.