Cathode Ray Tube based video projector capable of horizontal scan rates of 31,500 Hz allowing the projector to display line doubled video and computer VGA graphics (at 640 by 480 resolution). A data grade projector has a horizontal scan rate double that of a video projector, which has a rate of 15,750 Hz. Graphics grade projectors feature a horizontal scan rate of 63,000 Hz enabling them to display line-quadrupled video as well as super-VGA computer screens (1,024 by 1,280 resolution). ll three projector types are distinguished by their ability to scan a certain amount of horizontal information per second. They will all display the same quality video when fed a basic NTSC signal that is not line doubled or quadrupled. However, the projectors possess more functionality as their horizontal scan rates increase. Graphics grade and most data grade projectors are capable of displaying HDTV signals in the full HDTV resolution (with the addition of a digital television tuner that is HDTV capable). ata grade projectors cost about 50 percent more than basic video CRT projectors, and graphics grade units cost about twice as much as basic video projectors. Data grade units offer a great degree of flexibility in video formats and quality.