Digital TV for Dummies
The last resolution is a little tricky. 1080p. 1080p is done in 2 ways depending on the picture source. The first is 1080p 30f/ps. This means the scan rate is 1080 line scanned progressively at just 30 times every second. This is for HD digitally recorded programs like concerts that look live but are recorded. The second is 1080p 24 f/ps. The same scan method, except the scan rate is just 24 frames per second. This is done to show movies in 1080 line HD at the same 24 frames per second as the movie was recorded. A 720p TV has a “Pull-Down for 24 f/ps movies. It is a conversion process that allows 24 f/ps movies to be viewed normally at the 720p 60f/ps rate.
The best picture quality from lowest to highest in order are as follows. 480i, 480p, 1080i, 720p, and 1080p. You will notice that 720p is ranked better than 1080i. This is because 60 frames of 720 lines is sharper and clearer than 30 frames of 1080 lines. Most sports and a few entertainment channels use 720p exclusively because the 60 f/ps makes the fast movements look smoother without jitter. At the bottom of this page, is a link to a page that lists most of the popular networks and what HD resolution mode they use.
The standard for all digital TV audio is Dolby digital and Dolby 5.1 digital surround. So every digital station will have DVD audio quality, and capability.
Digital stations can also broadcast more than one program on the same channel. These are called subchannels. A single digital TV transmission can broadcast 2 HD and 1 SD channels. Or they can broadcast 1 HD and 4 SD channels. Or they can broadcast up to 10 SD channels. They can also send data, CD quality stereo music, and text on several subchannels. This has increased the income that TV stations can make by carrying more than one network on the same channel at the same time.
I wanted to dispel a myth or two about selling features on HDTV sets. First, many manufacturers are telling you what the refresh rate is on their TV. Some say 120Hz, and others are up to 240Hz. They are saying that the circuitry in the TV refreshes the picture up to 240 times per second. This selling point is Bull Shit. It is a gimmick that has no effect on how the TV looks. The resolution of the HDTV is either 720p or 1080i.
A 720p TV display scans at 60 frames per second. Refreshing it 240 or 240,000 times per second will not change the fact that the TV still only scans at 60 frames per second. The refresh rate is just a gimmick to impress you when you are shopping. But it really means nothing. Any one who says they see a difference with higher refresh rates, is just believing what they were told, and imagining it. Your eyes can not see more than about 75 frames per second.
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