Televison Buyer's Guide, Part 2
The Lines Are Drawn
Now that you know where you will put your new TV and how you will be using it, what kind of television do you buy? You probably want High Definition for the main TV in your house, but is it necessary for a second TV? Here's where all the terminology can get confusing. Before we go any further, let's understand what the terms mean.
Signal Types
You've probably heard a lot about "digital" television and "HDTV" or "hi def" television. The terms refer to the kind of signal coming to your television set. No matter how you get your TV signal, by antenna, satellite, or cable, you are getting either a digital or analog signal from each station.
Analog: The television we've been used to all our lives is analog. The standard-definition programs found on regular TV, cable, or satellite channels--including digital cable and DirecTV or Dish Network -- usually analog.
Digital: A "digital" signal is available over the air, by cable or satellite. Digital does not mean high definition. A digital signal can be SDTV, EDTV, or HDTV. See below for definitions.
Interlaced and Progressive: Interlaced and its companion term Progressive scan refer to the way the picture is drawn on the screen. Every television picture is made up of lines. The old standard NTSC picture was 525 lines, newer televisions have resolutions of 480, 720, and 1080 lines. The more lines to the picture, the finer the image, at least in theory. But the way the lines are drawn is important. An interlaced signal paints every other line (such as 2, 4, 6, 8) and then comes back to paint the other lines (1,3,5,7) and completes the entire image in one thirtieth of a second. (See image to right. Refresh the page to see how the interlaced image is built, at a much reduced speed of course..) A progressive scan paints every line in order (1,2,3,4) in the same time period. A progressive scan image is sharper and has fewer artifacts or "jaggies" than an interlaced scan.
SDTV: A standard-definition television is an analog television equipped with a built-in ATSC* tuner that allows it to receive digital TV broadcasts. It will display a picture from these broadcasts, but HDTV shows won't look nearly as detailed as they would on a true HDTV.
EDTV: This stands for Enhanced-Definition TV, and usually it describes a television that can display HDTV signals at the lowest allowed resolution, 480p or 852 x 480 pixels. This sets will not produce the highest quality HDTV image.
HDTV: Most digital televisions are high definition televisions, or HDTV. They come in several resolutions, 720p, 1080i, and 1080p. These sets can display standard TV, progressive-scan DVD, and HDTV signals.
Next -- You Say You Want Resolution
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*ATSC - Advanced Television Systems Committee, set up by the the industry and approved by the US government, this committee adopted the official digital television standard for the United States in 1997. These days, ATSC means a tuner capable of receiving digital and high definition signals.
NTSC - National Television Standards Committee, the group that developed the television standards used from 1941 until the present for analog television signals. The television standard that has been used in the US is also referred to as NTSC and an NTSC tuner is one that will receive only the older style signals.