Don't forget about the end user

By Brian Dipert, Technical Editor -- EDN, 11/8/2001

While researching my recent series of video articles, I had the opportunity to evaluate three DTV (digital-television) receivers: Mitsubishi's (www.mitsubishi-tv.com) SR-HD5, Panasonic's (www.panasonic.com) TU-HDS20, and Princeton Graphics' (www.princetonhdtv.com) HDT-2000. I used them with a roof-mounted (20-ft-pole) Terk (www.terk.com) TV35 antenna, Princeton Graphics' AF3.0HD wide-screen display, Panasonic's Technics SA-DX1050 audio receiver, and a multivendor surround-plus-subwoofer speaker set.

First, the good news: all three receivers solidly tuned in all NTSC (National Television Systems Committee) and ATSC (Advanced Television Systems Committee) channels in my broadcast area, a ringing endorsement of 8-VSB (eight-level vestigial-sideband) demodulation and particularly impressive given my neighborhood's poor reception characteristics. Go to www.antennaweb.org and enter my office address (1864 52nd St, Sacramento, CA, 95819) to get a visual explanation of the challenge the receivers faced. And, when I watched a film-captured program or a video-captured program that has been carefully converted from interlaced to progressive scan, with an accompanying 5.1-channel audio track, the multimedia quality blew me away. Enough of this type of programming and my wife and I might actually watch more than one or two hours of television per week.

Alas, enough programming is only one of several serious challenges facing DTV as the Federal Communications Commission's 2006 deadline for analog-to-digital conversion looms. I could spend an entire editorial ranting about the chicken-or-the-egg-type finger pointing going on now among broadcasters, cable operators, and equipment suppliers. The fact is, though, that even if all the broadcasters immediately switch over to creating their new television material in a wide-screen, progressive-scan-captured digital format, most of what DTV will broadcast for decades to come will be digitally converted analog-video archives. Think, for example, about all those Happy Days and Gilligan's Island reruns!

How does DTV handle this analog- and interlace-sourced material? Horribly, if my experience—highlighted by my high-resolution progressive-scan display, which uncovers quality sins that older interlaced sets obscure—is any indication. In my survey of morning talk shows, mid-day soap operas, evening sitcoms, and weekend sports programming, I saw lots of blocky MPEG compression artifacts, temporal "jaggies," color-fringe moire patterns, fuzzy edges, and overall soft images. Was this mediocre quality a function of poor encoding at the broadcast end or of poor decoding at the reception end? I don't know for sure (although I strongly suspect the former). But I don't care, and the average consumer won't either. It's sad but true that digital 480i generally looks worse than analog NTSC, either on my old TV or after I ran it through a Focus Enhancements (www.focusinfo.com) QuadScan Elite or Silicon Image (www.siimage.com) iScan Pro video processor before displaying it on the AF3.0HD.

Some broadcasters insist—when displaying 4-to-3 aspect ratio material in a 16-to-9 format—on horizontally stretching the image, thereby creating disproportionately short-and-fat objects. If you watch only one television channel, your eyes and brain eventually compensate, but channel surfers don't have that luxury; why the broadcasters don't keep the 4-to-3 aspect ratio and simply put gray vertical bars on either side is beyond me. Video quality, unfortunately, isn't DTV's only shortcoming. The Princeton Graphics HDT-2000 provides only a six-channel analog output and no S/PDIF (Sony/Philips Digital Interface)—a baffling omission considering that digital-audio signals run around inside the unit. Newer audio receivers provide six-channel analog inputs, but they target DVD-Audio or SACD (Super Audio CD) players. And hardly any receiver more than a year old has them.

The HDT-2000 can also output two-channel conventional analog audio and Dolby Surround, but what's the point? Two- and four-channel matrix-encoded audio is a lame substitute for the real thing (six discrete surround channels). The Panasonic TU-HDS20 provides S/PDIF outputs, but their halfway-complete implementation is no less aggravating. They work only when the unit receives an ATSC channel, meaning that if I want to watch PBS (which doesn't yet broadcast digital content in my area) or an independent station, I have to make an additional two-wire connection between the TU-HDS20 and SA-DX1050, then switch the audio receiver's TV input from digital to analog, and back again for a subsequent ATSC channel.

The Mitsubishi SR-HD5 almost got audio right; the unit outputs Dolby Digital or PCM (pulse-code modulation) over S/PDIF when it receives ATSC broadcasts, and PCM for NTSC. I say "almost" because the bit streams that both the SR-HD5 and the Panasonic unit generate occasionally confuse the digital-decoding circuitry in my audio receiver, necessitating one or sometimes several transitions away from and then back to the desired channel before sound comes out the speakers. Do the television receivers cause this problem, or does the audio receiver cause it? Again, I suspect the former, because the Technics handles my DVD player's Dolby Digital and PCM outputs with aplomb. But again, it doesn't matter. The S/PDIF, Dolby Digital, and PCM formats have been around long enough that less-than-100% interoperability is inexcusable.

My final gripe concerns channel tuning and identification. All three units contain automatic-channel-scanning and programming features, yet the SR-HD5 stubbornly refuses to find the ATSC version of channel 58. When I manually punch "35-2" into my remote control, however, the SR-HD5 reports a strong signal and dutifully adds the channel to its list. Channel designations represent baffling idiosyncrasies. One DTV receiver might report the digital version of Fox network channel 40 as channel "61"; another might call it "40-1." The same unit might even switch from one designation to the other after autoreprogramming.

After using these supposed second- and third-generation DTV receivers, I find it hard to believe that they went through much focus-group testing before their release. They're just too clumsy and nonintuitive to operate—even for a technoid like myself. Quite a few pundits are predicting that the FCC will extend its self-imposed 2006 deadline to give everyone more time to make the analog-to-digital switch. This idea is great. The technology is ready for prime time, but the implementations are not. And the last thing anyone wants is another widget whose reality falls far short of the promises made to consumers.

Our engineering mentalities are both our biggest blessings and our greatest curses. To paraphrase a common expression, they result in us getting so close to the forest that we lose sight of the trees. We sometimes kid around about how we can't explain what we do to our spouses, relatives, and friends. That's a problem, not something to brag about. It's a bug, not a feature.

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