Digital television (DTV) is the sending and receiving of moving images and sound by discrete (digital) signals, in contrast to the analog signals used by analog TV. Digital television supports many different picture formats defined by the combination of size, aspect ratio and interlacing.
There are a number of different ways to receive digital television. One of the oldest means of receiving DTV is using an antenna/aerial. This way is known as Digital Terrestrial Television (DTT). With DTT, viewers are limited to whatever channels the antenna picks up. Signal quality will also vary. Other ways have been devised to receive digital television, including digital cable and digital satellite.
Digital television broadcast standards include the DVB family used throughout Europe including DVB-S (satellite), DVB-T (terrestrial), and DVB-C (cable); the ATSC family used throughout North America including ATSC (terrestrial/cable) and ATSC-M/H (mobile/handheld); and the ISDB family used throughout Japan and South America including ISDB-S (satellite), ISDB-T (terrestrial) and ISDB-C (cable).