| The recent technological breakthrough in broadcast signals from the traditional analog NTSC, PAL, and SECAM formats to a digital signal format with a higher resolution is called as High-Definition television (HDTV). A consortium of companies such as AT&T, General Instrument, MIT, Philips, Sarnoff, Thomson, and Zenith formed the Digital HDTV Grand Alliance and introduced the technology for the first time in the USA in 1990.
HDTV broadcast standards lay down specifications to have a resolution of 1080 active lines and a 16 x 9 aspect ratio in ITU-R BT.709. The ATSC broadcast standard uses a resolution of 720 lines across the United States and few other countries. The standard is referred by a specific notation stating the number of lines in the display resolution, Progressive frames (p) or interlaced fields (i), and Number of frames or fields per second. For example the format 1080i50 has a resolution of 1920 × 1080 pixels with an interlaced encoding at 25 frames per second. According to the standards, the 720p is more suited to fast action sequences due to the progressive rendering as against the 1080i using the interlaced fields much suited for slower motion picture.
With the advent of such high resolution broadcasts, latest developments in television technology have incorporated support for such standards. Most projection television sets introduced have in-built HDTV receiver units. These units intercept transmitted data, process the same, and finally produce the output depending on the size of the television screen. For television sets capable of reproducing high resolution images, processing the signal feed cannot be achieved in the absence of a HDTV receiver or “tuner”. Most tuner-sets are designed as small external units placed beside the television with the HDTV signal cable attached to them. Prominent consumer electronic manufacturers such as Viewsonic, Samsung, Hughes, Toshiba, etc manufacture HDTV tuners capable of processing wide range of broadcasts signals. For users demanding an HDTV experience on their personal computers, HDTV receiver units are available as expansion cards from manufacturers such as Pinnacle, Avermedia, etc. |
