Although most people are mesmerized by the wide screen and high resolution picture of HDTV, there are a lot of other things about high definition television to be interested in. For example, many people don't know exactly how that high resolution picture in created. With any type of TV display, the picture is made up of horizontal lines of pixels that are scanned onto the screen from top to bottom. In the past, odd numbered lines of resolution (every other line) was scanned onto the screen from top to bottom, followed a small fraction of a second later by the even numbered lines. This method of creating a TV picture is called 'interlaced scanning' and is still the dominant method of creating a TV picture. This process happens so quickly that the human eye just sees the picture as a whole image, but it has the disadvantage of creating defects in the picture called motion artifacts while displaying fast movie objects.
The other method of creating a TV picture is scanning the picture onto the screen all at once. With this technique (which is called 'progressive scanning'), even and odd numbered lines of resolution are scanned on in sequence in one pass. This creates a complete picture which isn't subject to the motion artifacts of interlaced scanning.
The actual picture resolution is determined by the number of horizontal lines of resolution that the picture is composed of, and the more lines that are in the picture, the more detailed the picture is. For example, normal TV has a resolution of 480i (where the 'i' indicates interlaced scanning and the '480' indicates the number of horizontal lines of resolution), and a format called enhanced definition TV has a resolution of 480p (where the 'p' indicates progressive scanning). Actual HDTV can have resolutions of 720p, 1080i, or 1080p; though 1080p isn't widely supported right now.
The higher resolutions of HDTV pictures also create the need for more sophisticated receiver hardware to process pictures with those resolutions. The satellite TV provider, Dish Network does an especially good job of providing versatile HDTV satellite receivers to its subscribers. Currently Dish Network offers two models, which together provide just about all of the functions that someone could want in a high def satellite receiver.
The ViP211 is the basic model and it can handle the standard definition TV resolution of 480i, the enhanced definition TV resolution of 480p, as well as both of the most common high def resolutions: 720p and 1080i. This model also provides access to all of the features that Dish Network subscribers have come to enjoy with any satellite receiver.
The ViP622 DVR, is currently the most advanced satellite receiver offered by Dish Network. It has all of the capabilities of the ViP211 to display a variety of TV formats and access Dish Network's value adding receiver features, but it also includes a digital video recorder and the ability to watch different programming on two different TV sets at the same time. The digital video recorder is the really impressive addition to this model. It allows its users to easily record any TV show or movie, regardless of whether or not the user is at home when the program is aired to initiate the process. The DVR also contains a hard disk large enough to store up to two hundred hours of 480i video or as many as thirty hours in high def video format.
Dish Network HDTV receivers are a fascinating development of HDTV technology.
