Differences between “digital cable,” “digital satellite” and “HDTV”

Just because a program arrives through a digital cable or digital satellite doesn’t mean it is in high-definition. Much of today’s programming – even that received from a digital satellite, digital cable or even a digital channel broadcast over-the-air – is delivered in SDTV. You’ll get a better picture than you get with the analog broadcasts TV has used for years, because a digital picture will be free from the “ghosts” and “snow” that can plague analog transmissions. At a minimum, over-the-air SDTV offers a picture 640 pixels wide by 480 pixels high, totaling 307,200 pixels – about 50 percent more than today’s analog TV. A standard definition picture will be good, but not nearly as sharp and crisp as high-definition, which can go up to two million pixels.

Source: cea