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By way, if you have a digital box from cable company, you have only a handful of digital channels, rest are same if you remove cable box.
Satellite companies like Direct TV (or DirecTV) and Dish Network, provide national satellite service with hundreds of digital stations. The picture is clear and crisp, especially if you spring for a high definition receiver to match your HD ready TV. While most cable signals are below 150 lines of interlaced resolution, standard satellite can approach DVD quality (480i) and HD content will be sent at either 1080i or 720p (progressive). A regular 27” TV has capability of no more than 500i while a HD television can produce full range.
What are interlaced and progressive signals? Interlaced broadcast was developed from old NTSC format where designers in 1920’s and 30’s couldn’t get TV to scan every line from top of screen to bottom fast enough. They needed to cheat by having TV scan all odd lines; 1, 3, 5 etc. then go back and scan even lines; 2, 4, 6 etc. The result is thick black lines running horizontally across your screen and only half picture appearing. These flickering lines prevented you from sitting close to television without getting eye strain. As TVs got bigger, you sat farther away.
The new HD televisions scan all lines progressively and refresh screen much quicker. It is like looking through your front window with horizontal blinds. Turn rod so blinds are half open. The street outside is now half covered like interlaced pictures and you only see half picture at one time. Now pull cord to fully open blinds. You now see entire window unobstructed or like a progressive signal.
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