If you've ever taken a look at the features included on Dish Network high definition satellite receivers, you're probably blown away by all of the technical terminology and the lack of explanation that accompanies it. While it's frustrating to try to sort through the information in those brochures, you you should keep in mind that the people who wrote them are probably engineers who are trying to put a lot of information into a small space. We don't have the disadvantages of a small amount of space or being engineers, so this article should be able to clear some things up that those brochures don't make clear.
One of the most confusing things that high definition satellite receivers are supposed to deal with are different TV resolutions. For example, some brochures say that the receiver can display TV resolutions of 480i, 480p, 720p, and 1080i; which is meaningless if you don't know anything about how televisions produce pictures on their screens. In the case of these resolutions, the number defines the number of horizontal lines of resolution and the letter designates how those lines are scanned onto the screen. The higher the number higher the resolution and the more detailed the picture. As far as the letters go, the "i" means that those lines of resolution are scanned onto the screen in an interlacing pattern, and the "p" means that the lines are scanned onto the screen in a progressive pattern. With an interlacing pattern the odd numbered lines are scanned onto the screen from top to bottom and the even numbered lines are scanned on a thirtieth of a second after that. Because the process happens so fast, it looks like a complete picture is formed on the screen all at once, but an interlacing picture is subject to visual defects under certain conditions. Those visual defects are eliminated with the use of progressive scanning in which all of the lines of resolution- even and odd- are scanned onto the TV screen in one pass.
As to how those resolutions translate into which kinds of programming you can watch using a Dish Network High Definition satellite receiver, it's actually pretty simple. Standard definition television, or SDTV for short, is the kind of television that we all grew up on, and has a resolution of 480i. High definition television can have resolutions of either 720p or 1080i, though many high definition television sets will up-convert 1080i programming so that it's displayed on the screen in a progressive pattern instead of an interlacing one. The 480p resolution is an in-between television format called enhanced definition television, or EDTV.
Another thing that many people find confusing about high definition television receivers is that they can display both MPEG-4 and MPEG-2 Dish Network programming. Both MPEG-2 and MPEG-4 are data compression technologies that are necessary because of the huge amount of data needed to transmit television programming. MPEG-2 is an older data compression technology that's typically used to compress standard definition television programming so that it can be managed more easily by the hardware that makes up Dish Network's transmission equipment, the satellites themselves, and the receiver equipment. Because high definition television has a higher resolution picture and a wider screen, it's a much more data intensive television format than standard definition television and therefore needs to be further compressed using the newer MPEG-4 data compression technology so that the equipment can handle it. The fact that a receiver can decompress both MPEG-2 and MPEG-4 formats, just means that it covers all of the bases needed to handle both high definition television and standard definition television programming.
Hopefully this article clears of some of the confusion with the details of high definition satellite receivers.
