Digital television

Digital television transmits picture and sound as digitally encoded data rather than continuous analog waveforms. Compression and multiplexing let broadcasters carry multiple programs or high-definition video within limited spectrum.

MPEG transport stream: A packetized format that carries encoded audio, video, and metadata for digital broadcasting. It multiplexes program components into the stream sent by a digital television service.
Radio spectrum: The range of electromagnetic frequencies used for radio communication. Digital television shares finite spectrum with other services and must fit into assigned frequency bands.
Digital terrestrial television: Digital television broadcast from land-based transmitters to receiving antennas. It delivers digital programs over the air using terrestrial broadcast networks.
Analog television: Television that represents picture and sound through continuously varying electrical signals. It is the direct transmission format that digital television replaced in many broadcasting systems.
Video compression: Methods that reduce video data by removing spatial or temporal redundancy. Compression allows high-resolution programs to fit within a broadcast channel's capacity.
Channel capacity: The maximum rate at which information can be transmitted reliably through a communication channel. It constrains how many programs and what video quality a television multiplex can support.
Digital cable television: Television services delivered through cable networks using digitally encoded signals. Cable operators use digital transmission to expand channel capacity and offer interactive services.
Internet television: Television programming delivered over internet protocol networks rather than traditional broadcast channels. It delivers digital video through managed or public data networks instead of broadcast spectrum.
Digital modulation: The encoding of digital information onto a carrier wave by varying its properties. Broadcast standards use modulation schemes to transmit encoded television data over radio frequencies.
Multiplexing: The combining of multiple signals or data streams for transmission over one shared channel. Digital broadcasters combine several programs and service data within a single channel.

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