June 2000. Welcome back. By now you may have read about my equipment selection, paper design, construction, and fine-tuning. You may have read my upgrade piece, Pseudo EX, which describes how to add center surround decoding. And, you may recall that as I selected my original equipment, I tried to plan ahead for the eventual availability of HDTV program material. Well, it's time for me to add high definition television to the home theater.

Sources

There are currently three possible sources of high definition program content: terrestrial over-the-air transmissions; satellite distribution; and, cable distribution. Cable distribution is currently rare, and there are issues concerning the way the signal is to be delivered. Over-the-air broadcasts are modulated based on the 8-VSB transmission system as specified by the ATSC Digital Television Standard, but cable companies are not obligated to adopt this modulation scheme. They may use a competing scheme called COFDM; the choice has yet to be resolved. So this might not be a prudent time to buy an exclusively cable-based system.

I have other issues as well. I would prefer to own the media for the films I wish to enjoy; cable and satellite would force me to tape the films I wish to own on digital videocassettes (and they may employ digital copy protection schemes to foil me). Some satellite providers have decided to pan and scan 2.35:1 films in the 1.78:1 format for HDTV distribution; I object. And in the hierarchy of release dates, cable and satellite programmers are the very last commercial-free sources of film. So I'd be forced to pay hundreds of dollars each year for the privilege of waiting for films to be offered at the provider's convenience, and potentially in a format that deviates from the director's wishes. No, I'll purchase DVDs until HD-DVDs are available (which I expect within two to three years). For now, I'll begin with commercial terrestrial broadcasts.

Program Listings

It occurred to me that buying and installing HDTV is going to be expensive and will require some effort. So I wanted to know what program content is available before taking the plunge. Alas, this information is difficult to find. The best I've been able to do is connect to E-Town's HDTV Listings to read what the networks are planning for the week. (These listings also include HBO and Showtime.) But this page does not help me with independents. Nor does it tell me what's available within my particular reception area. If any reader has a better source of HDTV program listings, I'd appreciate your contacting me via e-mail.

Are There Terrestrial Broadcast Stations In My Area?

The Federal Communications Commission publishes some very helpful documents. The DTV TABLE OF ALLOTMENTS AND LOCATIONS is a list of all the DTV (digital television) stations approved for operation. The list may be found at Appendix B in this FCC document. But not all authorized stations are on the air. I live in the Northeast where I pull in broadcasts from New York City. Despite the fact that NYC is the largest broadcast television market in the country, only two DTV stations are active: CBS on channel 56; and, FOX on channel 44. Fortunately for me, by rotating my antenna to the South, I can receive signals from the fourth largest TV market, Philadelphia. From there may be found: ABC on 64; CBS on 26; FOX on 42; independent WFMZ on 46; NBC on 67; and, PBS on 43. If you're curious about your area, after you've consulted the FCC list of authorized stations, you'll have to get in touch with each station to determine if and when it will be on the air.

You'll notice that the stations are all in the UHF band. For those of you who grew up with cable, I'll mention that the broadcast television band is divided into two sections: 2 through 13 are in the VHF (very high frequency) band; and, 14 through 69 (formerly 83) are in the UHF (ultra high frequency) band. In an age when we routinely receive 12 GHz channels from satellite, the term UHF seems somewhat quaint; all its channels are below 1 GHz. UHF's high frequency transmissions do require some special care to receive them properly, as UHF tends to be more line-of-sight than VHF. Building materials attenuates UHF more than VHF, so indoor antennas are less effective, and DTV needs a very strong multipath-free signal to avoid blocking or lost frames or lack-of-lock.

I should mention that there's a small, behind-the-scenes controversy quietly raging in the DTV world in which some manufacturers (Sinclair is perhaps the most vocal) are claiming that the existing 8-VSB modulation scheme is not as robust as an alternative COFDM process (which was chosen for European DTV). It's claimed that 8-VSB may be more vulnerable to multipath (which appears as ghosting on analog television). This situation reinforces my suggestion that an external high-gain UHF antenna is essential to quality reception. (By the way, all indications point to retaining the exiting 8-VSB modulation scheme, so I'm not concerned about my HDTV investment.)

The Lost Art Of Antenna System Design

Cable and satellite distribution have become so ubiquitous that few have had to give a second thought to the design and installation of an antenna system and an RF distribution system. I've always resisted cable, choosing instead to find my films on video elsewhere. So I've always had a substantial antenna tucked into a spacious attic for broadcast TV, and a capable 75-ohm electronic system to distribute the signals around the house on high-quality coaxial cable. For HDTV reception, I have just the thing, a trusty old Channel Master Model 4251 Para-Scope UHF dish. This monster is 84 inches in diameter and resembles a satellite dish. I was surprised to learn that it's still on the market; have a look at Channel Master's UHF Antenna Page for a variety of excellent UHF antennas, most of which are physically small.

To ensure optimum signal strength, I installed a mast-mounted preamplifier on my antenna. This little electronic package boosts the signal right at the antenna before it has a chance to be attenuated by a long 75-ohm cable run. This preamp is equivalent to the low noise amplifier found on satellite dishes. Have a look at this Channel Master page for a variety of preamps .If you want to send these signals to a number of sets, you'll next need an active distribution amplifier. Visit another Channel Master page for distribution amplifiers. If you want to be able to pick up signals from more than one location, or if you wish to fine tune antenna pointing from your home theater, you may also want an antenna rotator. Start at this Channel Master page to navigate to various rotator products.

How To Aim

Being able to aim the antenna and touch up its direction becomes a bit tricky for DTV. Unlike analog TV in which the signal becomes weaker and noisier as you rotate the antenna away from the proper direction, digital TV's picture essentially remains unchanged - to a point - since the MPEG-2 compression algorithm provides error correction. As the signal weakens, you may see some blocking; then the picture will abruptly vanish. So without an RF signal strength meter of some kind, aiming can be tough.

If your DTV stations' transmission antennas are collocated with your UHF analog broadcast stations' antennas, you're in luck. Just use a conventional television to watch an appropriate UHF analog TV program. Rotate the antenna clockwise, then counterclockwise, noting the directional angles of equal snow (video noise) on the screen. Then split the difference between the two angles .If you see any ghosting, fine-tune the angle a touch in either direction for the best-looking image. When you have a great picture, you'll have a strong signal. If digital and analog transmission antennas are not collocated, it gets complicated. Fortunately, the Web offers some help. In the same document that lists authorized channels and starting on page B-43 you'll find the longitude and latitude of each transmission antenna. How does that help? Go to Geocode or MapBlast and you'll be able to find the latitude and longitude for your address. Then head back to the FCC to use its utility to calculate the bearing from your location to the HDTV station. You'll want to use a magnetic compass to aim your antenna; unfortunately, it doesn't point with respect to True North, the reference for latitude and longitude. You'll have to know your local magnetic declination, the deviation between Magnetic North and True North. Go to the National Geophysical Data Center to find your magnetic declination from North. Note that West declinations are assumed to be negative while East declinations are considered to be positive; so True Bearing = Magnetic Bearing + Magnetic Declination. My local magnetic declination is -13 degrees, which is enough to reduce my signal strength considerably if I had ignored it.

This whole process may seem a bit extreme, but the effort was worth it. When I was finished assembling and aiming my antenna system, I had a very strong and stable signal without a hint of multipath on my analog television receiver.

Receiving DTV

We've seen the introduction of many DTV and HDTV products over the course of the last year. Of particular interest to me was the category of set top boxes (STBs), which are essentially receivers without displays. Each accepts a signal on its antenna input, allows you to tune to specific channels, sends the received digital bit stream to an onboard MPEG-2 decoder, and spits out analog video, and both analog and digital audio (the DTV standard specifies Dolby Digital sound). There are over a dozen such boxes on the market but my requirements quickly limited my choices.

I wanted to be able to watch HDTV picture formats just as they were transmitted, so the STB would have to pass them through unaltered. I'll explain. There are eighteen video formats within the approved DTV standard. Eighteen. So far as I'm aware, as of this writing, broadcasters have chosen to offer two: 720p60 and 1080i30. (Conventional television resolution in a 4:3 aspect ratio is often upconverted by the DTV station to either of these two formats - particularly for commercials - and shown with black bars on either side of the HDTV widescreen aspect ratio. The source of such images can be NTSC interlaced video.) 720p60 offers an image that measures 1280 pixels wide by 720 pixels high at a progressive frame rate of 60 pictures per second. 1080i30 offers a picture that measures 1920 pixels wide by 1080 pixels high at an interlaced frame rate of 30 pictures per second. Each is shown in an aspect ratio of 16:9 (seem familiar?) and both may be considered to be HDTV (although some will argue that 720p60 is not high definition). Almost all STBs upconvert 720p60 to 1080i30 .In my humble opinion this conversion cannot be accomplished without a loss of detail or the appearance of artifacts. So I insist upon passing native formats.

My other requirement is to be able to record off-the-air. I like to time-shift, I don't like to be a slave to broadcast television's schedule, and I prefer to fast scan through commercials. This narrows the field to one STB, the Panasonic TU-DST51, and its companion Digital VCR, the Panasonic PV-HD1000. They interconnect using the IEEE 1394 digital interface, better known as Firewire. This combination is intriguing; the recorder accepts and records the MPEG-2 bit stream from the STB and sends it back to the STB for decoding during playback. So the recording should exhibit no loss in quality whatsoever in either the video or audio portions of the program. Neat.

Should my local cable company decide to offer HDTV in the 8-VSB modulation scheme, the Panasonic is capable of dealing with that cable signal. For those of you who may decide to buy an HDTV display incapable of accepting 720p60, the Panasonic STB will upconvert it to 1080i30 with a simple slide switch change on its back panel. In fact, you have a choice of Native (my preference), 1080i and 480p, 480p only, and 480i (conventional NTSC). As with DVD players, the STB allows you to select your display's aspect ratio. (There are a number of display modes that affect the way the video is written to the screen.)

Setup and option selection is a snap. A clever little onscreen rotating main menu guides you to pages named Setup, Timer, Display, and D-VHS. The Action and navigation buttons on Panasonic's universal remote control are intuitive. Since there is a digital interface to the DVHS recorder, both content and control signals may be passed. The STB can control the recorder and even make automatic recordings. Unfortunately, there are only two Timer memories in the STB, and they're only programmable over the next seven days. The recorder has its own eight memories, but the recorder can't change the STB's channel, nor can it turn the STB on and off. So to record under the recorder's control, the STB must be left powered and only one channel may be recorded. The recorder is also capable of conventional VHS recording, and is capable of pseudo-S-VHS playback at reduced resolution.

Interfacing

While the Panasonic seems to be my only choice, it comes with some serious interfacing challenges - at least for me. The video output is in component form only; my projector requires RGB-HV. And the digital audio output is in optical form only; my B&K Decoder/Preamp requires a coaxial connection. And how can I switch back and forth between the output of the Faroudja Line Doubler used for DVD playback and the HDTV STB?I'm forced to invest in outboard electronics to perform some transparent conversions and video switching. I chose two superb video products from Extron, the CV200 Component-to-RGB-HV Converter and the SW2ARHVxi RGB-HV switcher. I also chose a delightfully simple little converter from Midiman, the CO2, to transform the optical digital audio signal from the Panasonic to a coaxial digital audio signal suitable for the B&K. (For a more detailed discussion of these products, have a look at my article The Ins And Outs Of Interfacing.)

I should mention that DVD component video is not the same as DTV component video. DVD's component video jacks might be labeled Y, R-Y, and B-Y for Luminance, Red minus Luminance, and Blue minus Luminance. (Green is recovered mathematically in your display's component video electronics.) DVD jacks might also be labeled Y, Cb and Cr; these are the same signals. DTV component video jacks are labeled Y, Pb, and Pr; a similar signal format, but not the same. DTV's component video is tri-level sync and has a higher bandwidth than that of DVD.

Does All This Stuff Work Together?

As I interconnected all these components, the cabling mess that's the back of my equipment rack quickly became a nightmare. It took thirteen video cables just to get the video from the STB to the converter, from the converter to the switcher, and from the doubler to the switcher. And then there are the audio connections, the antenna connections, the IR emitter for remote control, the Firewire, and the separate connections to the NTSC tuner Panasonic generously included in the STB.

I flipped the switch on the back of the STB that forced passing all transmissions in their native formats. This puts the STB in the 1080i30 mode for all onscreen menus. So after I eagerly fired up my system, I first had to establish a new memory in my NEC projector. The projector dutifully locked onto the 1080i30 video and reported a 33.75 KHz horizontal scan frequency and a 61.46 Hz vertical scan frequency. I copied the screen convergence data from the memory that serves the line doubler, labeled and stored the memory, and I was off and running. With the antenna aimed at New York, I asked the STB to scan the airwaves for DTV stations. It found the two operational stations, CBS and Fox. I tuned to Fox and repeated the NEC's new memory process for Fox's 720p60 transmissions. Once again, the NEC locked on, this time to report 45.02 kHz horizontal scan frequency and 61.32 Hz vertical scan frequency. I once again copied the line doubler's screen convergence data, labeled the memory and stored. I enabled digital audio for the Video 2 input of the B&K Decoder/Preamp, and AC-3 appeared on its display. I had picture. I had sound.

(For those who may be interested, if I can trust the NEC's numbers, it would seem that there are nine additional horizontal scan lines in the vertical interval for each of 1080i30's fields, and fourteen additional horizontal scan lines in the vertical interval for each of 720p60's frames.)

Was It Worth It?

Conventional wisdom indicates that to achieve HDTV's full resolution potential, nine-inch CRTs are required. The larger diameter reduces the tube's spot size with respect to its total image size; this greatly increases resolution. My NEC projector is equipped with only seven-inch tubes but it does have electromagnetic deflection. It's rated at 1280x1024 pixels. My home theater is in a room as dark as the inside of a coffin, which permitted me to reduce the projector's contrast and brightness (while retaining proper settings based on the AVIA Guide to Home Theater DVD). Reduced contrast and brightness also reduces the spot size. But I wasn't sure just how much of HDTV's resolution I'd be able to perceive. As it turns out, quite a bit.

CBS transmits much of its primetime programming in 1080i30, and so I sat down to watch "Judging Amy." At first, commercials in disappointing-looking 480-line video in an aspect ratio of 4:3 were on the screen. Then CBS faded to black, there was a short pause, and the network switched to a full-resolution, widescreen, helicopter shot of New York City - its HDTV signature logo .It was virtually three-dimensional. The level of detail was truly impressive. My screen is sufficiently far away to allow me to focus my eyes at infinity, so the view of New York was like drifting over the Hudson River in a hot air balloon. Quite an illusion.

The show began, and I was immediately startled by visible textures in fabrics and wood. Individual hairs on the actors' heads were clearly visible. Small print on background objects could be read. All scan lines were gone. No visible edge enhancement was detectable. The series is shot on film, and the image looked like film. Since 3:2 Pulldown is used to transfer the film to video, interfield motion artifacts are no more visible than for any other film source on video. (Had the series been videotaped from an interlaced, sixty field-per-second camera, motion artifacts would have been more visible.) The colors were vibrant, perhaps a bit too vibrant. Contrast was high and brightness seemed low. I touched the video up by eye. The images were absolutely gorgeous.

The sound was a bit more problematical. The front center channel seemed to have been placed in the surrounds, creating the audible illusion that the actors are closer to the listener than the screen. This, I'm sure, was a result of some inventive mixing at CBS and does not imply that there is anything wrong with the audio format.

Days later, I sat down to watch "Ally McBeal" on Fox. I was surprised that I could clearly see less detail in Fox's 720p60 images than CBS's 1080i30 images with my little seven-inch tubes. Nonetheless, the picture was terrific, providing a level of detail I had not previously seen in this clever David E. Kelley series. The only other show Fox routinely offers in HDTV is "The X-Files." Not a bad choice.

I programmed the Panasonic Digital VCR through the STB to record the season finales of a couple of CBS series, which requires digital videocassettes. Upon playback, the recording was indistinguishable from a live transmission. Very impressive.

Since I started work on this HDTV project (and article), I've learned that Panasonic ceased production of my STB and is about to introduce a new STB in which a digital satellite receiver section has replaced the NTSC tuner. Unfortunately, at the request of the satellite program providers, the Firewire port has been removed from this new model. But limited numbers of the STB I've described is still available at stocking dealers, and the recorder will remain in production to satisfy existing STB owners.

How does HDTV stack up to DVD?

I'm sorry to report that either HDTV format - 1080i30 in particular - puts the finest anamorphic DVD to shame. Consider the differences between VHS and anamorphic DVD. The improvement from anamorphic DVD to 1080i30 HDTV is that dramatic.

I've read of several technological breakthroughs that would accommodate HDTV's higher bit rate on optical disc. At least two don't require a blue or violet laser, which currently have a limited lifetime. It's my impression that within two or three years HD-DVD will be introduced. And if the studios' copy protection issues can be resolved, we may see some content. Then get out your wallets; it'll be time to build our film libraries all over again.

Take comfort in the knowledge that HD-DVD may be the last time you'll have to buy the same films again. In my critique of the digital projection of The Phantom Menace (Part One and Part Two ), I revealed that the video format was an anamorphic version of 1080i30. And you're probably already aware that George Lucas is "filming" Episodes Two and Three of the Star Wars series in an anamorphic form of 1080p24 video. So with the proper equipment and with HD-DVD as a source, it will be possible to essentially replicate motion picture theater resolution at home.

Interestingly, that may be an impediment to the studios. Not only are they concerned about selling copies of their movies in a quality that approaches 35mm film, they may not be able to sell us their back-catalog ever again after we've purchased the HD-DVD versions. We live in interesting times.

Wrapping Up

When I started this series, several of you wrote to ask if I could show you some pictures of my completed theater. The theater's colors are dark and lighting for photography was difficult, but I can direct you a few modest quality photos in a picture gallery. Thanks for joining me on this journey. I hope my experiences have provided a little insight into the complexities of creating a theater at home, and you found them helpful as you plan your own.

(If you have any questions or comments for the author, say hello to Mr. Blandings here.)