As of Mar. 1, 2007, the Federal communications Commission required newly manufactured television sets to be manufactured with built-in digital receivers. Where older analog television sets are used to receive free over-the-air television broadcasts, a separate digital terrestrial receiver and converter is required.
Terrestrial digital broadcasts are transmitted on two frequencies: very high frequency channels 2-13 and ultra high frequency channels 14-51. To receive digital broadcasts, a receiver must use an antenna designed to receive both UHF and VHF signals.
Where digital converter boxes are used to down-convert digital signals for use on an analog TV, the picture quality does not reach digital quality. There are three types of digital broadcast qualities. Standard Definition is used for both analog and digital broadcasts. Enhanced Definition provides better picture and sound quality than SD. High Definition broadcasts, available through digital receivers, is the highest quality of picture and sound available.