Digital terrestrial televisionDigital terrestrial television (DTTV or DTT, or DTTB with "broadcasting") is a technology for terrestrial television in which land-based (terrestrial) television stations broadcast television content by radio waves to televisions in consumers' residences in a digital format. DTTV is a major technological advance over the previous analog television, and has largely replaced analog which had been in common use since the middle of the 20th century.
TeletextTeletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipped television sets. Teletext sends data in the broadcast signal, hidden in the invisible vertical blanking interval area at the top and bottom of the screen. The teletext decoder in the television buffers this information as a series of "pages", each given a number. The user can display chosen pages using their remote control.
DatacastingDatacasting (data broadcasting) is the broadcasting of data over a wide area via radio waves. It most often refers to supplemental information sent by television stations along with digital terrestrial television (DTT), but may also be applied to digital signals on analog TV or radio. It generally does not apply to data which is inherent to the medium, such as PSIP data which defines virtual channels for DTT or direct broadcast satellite systems; or to things like cable modem or satellite modem, which use a completely separate channel for data.
819 line819-line was an analog monochrome TV system developed and used in France as television broadcast resumed after World War II. Transmissions started in 1949 and were active up to 1985, although limited to France, Belgium and Luxembourg. It is associated with CCIR System E and F. When Europe resumed TV transmissions after World War II (i.e. in the late 1940s and early 1950s) most countries standardized on 625-line television systems. The two exceptions were the British 405-line system, which had already been introduced in 1936, and the French 819-line system.
SECAMSECAM, also written SÉCAM (sekam, Séquentiel de couleur à mémoire, French for color sequential with memory), is an analog color television system that was used in France, Russia and some other countries or territories of Europe and Africa. It was one of three major analog color television standards, the others being PAL and NTSC. Like PAL, a SECAM picture is also made up of 625 interlaced lines and is displayed at a rate of 25 frames per second (except SECAM-M).
Gamma correctionGamma correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in video or systems. Gamma correction is, in the simplest cases, defined by the following power-law expression: where the non-negative real input value is raised to the power and multiplied by the constant A to get the output value . In the common case of A = 1, inputs and outputs are typically in the range 0–1.
Terrestrial televisionTerrestrial television or over-the-air television (OTA) is a type of television broadcasting in which the signal transmission occurs via radio waves from the terrestrial (Earth-based) transmitter of a TV station to a TV receiver having an antenna. The term terrestrial is more common in Europe and Latin America, while in Canada and the United States it is called over-the-air or simply broadcast.
Analog televisionAnalog television (analogue television) is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog signal. Analog signals vary over a continuous range of possible values which means that electronic noise and interference may be introduced. Thus with analog, a moderately weak signal becomes snowy and subject to interference.
Broadcast licenseA broadcast license is a type of spectrum license granting the licensee permission to use a portion of the radio frequency spectrum in a given geographical area for broadcasting purposes. The licenses generally include restrictions, which vary from band to band. Spectrum may be divided according to use. As indicated in a graph from the National Telecommunications and Information Administration (NTIA), frequency allocations may be represented by different types of services which vary in size.
Videocassette recorderA videocassette recorder (VCR) or video recorder is an electromechanical device that records analog audio and analog video from broadcast television or other AV sources and can play back the recording after rewinding. The use of a VCR to record a television program to play back at a more convenient time is commonly referred to as timeshifting. VCRs can also play back prerecorded tapes, which were widely available for purchase and rental starting in the 80s and 90s. Blank tapes were sold to make recordings.
