Buying any piece of electronic equipment is invariably an act of surrender. No matter how long you wait, you could always do better by waiting longer.
These days, the decision to buy a new television set is complicated by a radical new development in the industry. Digital broadcasts are due to begin in selected cities nationwide–including Chicago–by November, and you’ll need a special set to display these programs in their new, wide-screen format.
There’s a catch to the digital sets, though–the first round coming out this fall will be big-screen models costing upward of $6,000. And for the first few years at least, TV stations probably won’t broadcast much programming in the full digital glory known as high-definition television, or HDTV.
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For people who don’t have thousands of dollars to blow on a TV, then, it could be a long wait before it makes sense to buy a digital set. On the other hand, it’s not hard to find an affordable conventional TV that can be adapted later to display the basic digital picture. And for an extra $1,000 or so, you can buy a screen that will be able to display the two most common digital formats.
Of course, you’ll need to buy a digital converter box to enable any of today’s television sets to tune in the digital channels. The prices on those boxes have not been set yet, with estimates ranging from $400 or $500 for a basic converter to several thousand dollars for a more feature-rich one.
There’s not likely to be enough unique programming on the digital channels to justify buying the low-cost converter boxes when they arrive next year. The key now is to find a set that will adapt well to the digital environment to come.
The two basic elements of a television set are the receiver that tunes in the various channels and the monitor that displays them. With both of these elements, there is a huge difference between today’s sets and digital sets.
Today’s receivers can’t tune in digital broadcasts, and there’s no simple way to fix that. When the analog broadcasts end–maybe eight years from now, maybe longer–the receivers built into your analog television sets will essentially be useless.
On the other hand, the monitors in today’s TVs can display some types of digital broadcast, if connected to a digital receiver or converter box. The problem for the monitors is that they aren’t built to display as much information as some digital signals provide.
The current generation of TVs display 480 lines of information from top to bottom–showing the 240 odd-numbered lines first, then the 240 even-numbered lines a fraction of a second later–and 500 or more columns from left to right. That’s more than enough to handle today’s TV signals, which provide only about 330 discrete columns of information from left to right. The more finely detailed pictures from direct broadcast satellites and digital video disks, or DVDs, can include up to 450 columns of horizontal information.
The lowest quality digital signal provides the same number of vertical lines as an analog broadcast, but offers more horizontal columns–about the same as a DVD player. Today’s monitors can handle that one, engineers say. As you move up the ladder in quality toward HDTV, however, the signals quickly surpass most monitors’ ability to keep up in both the vertical and horizontal directions.
You’d then need a converter to view these digital signals that exceed the display capability of your monitor. You’d still see the complete picture, but without all the fine detail viewers would get with a higher-resolution monitor.
Another issue is the shape of the screen. Many of the digital broadcasting formats call for a cinematic wide screen, with a width-to-height ratio of 16-9. Today’s sets, by contrast, have a ratio of 12-9. So displaying a wide-screen digital broadcast on one of today’s sets means either cropping off the sides of the picture or shrinking it to fit with “letterbox” black bands at the top and bottom of the screen.
Chances are, however, that it will take years for much TV programming to appear in wide-screen formats. So the screen-shape problem isn’t likely to be significant for a while.
Even with these limits, a digital signal converted to run on one of today’s sets will still look better than an analog broadcast, engineers say. One reason is that broadcast digital signals don’t suffer from interference the way analog signals do, so they are free from ghosting, blur and other blemishes. You’ll either get the complete picture or, if the signal is too weak, none at all.
Another reason is the additional detail that even the lowest-quality digital signal can provide. The key to capturing that detail, though, is having the right connection between the digital converter and your set. There, consumers should look for sets with either “S-video” or “component” inputs.
Typically, televisions are connected to the video signals from VCRs and cable converter boxes by a single wire. This “composite” approach limits the amount of information traveling to the TV screen by cramming the color (“chrominance”) and black-and-white and brightness (“luminance”) data into one feed.
S-video, which stands for “separate video,” divides the information into two channels: one for color, one for black-and-white and brightness, although the two channels still travel on a single cable. This split allows more information to be passed on to the monitor, although the color channel must still be broken into two separate components by the set before it reaches the picture tube.
The S-video approach yields a better picture, engineers say, because it sharpens the edges of shapes on the screen and eliminates the rainbows and colored halos seen around patterned objects. Component signals go one step further, delivering a full signal to the set in completely separate cables that require the least amount of processing. This approach divides the information into three channels: one for blue, one for red and one for black-and-white and brightness.
By splitting reds and blues onto separate wires, engineers say, the colors on screen are purer and more faithful to the original signal. The result is an even better picture than S-video.
Most of today’s sets in the middle to upper price ranges, those selling for above $400, have S-video inputs; generally, S-video is standard on 27-inch models and above. Component inputs are harder to find, but manufacturers are putting them in an increasing number of sets to improve performance with the digital converter boxes to come. Look for them mainly in high-end sets, such as Sony’s 32-inch and 36-inch XBR sets, which carry suggested prices of $1,800 and up.
Again, most of today’s sets are not built to handle anything above the lowest-quality digital signal, with its 480 interlaced lines. CBS and the Public Broadcasting System plan to use that format for their daytime digital broadcasts as well as some of their prime-time broadcasts.
NBC, ABC and Fox are likely to use the next grade up, broadcasting 480 progressively scanned lines. Unlike interlaced signals, which alternate odd- and even-numbered lines, all the lines in progressive signals are displayed in quick succession.
The typical TV set today can’t display progressive signals, but computer monitors can. Several combination TV-PC sets (called “SVGA” monitors) are on the market that could handle both of the 480-line digital formats, albeit not on a wide screen; one example is Panasonic’s CT-36VG50, a 36-inch diagonal set with a suggested retail price of $3,200. These sets are pricier than conventional televisions, so consumers would have to pay more for that extra degree of digital compatibility.
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