simulcast

Simulcast (a portmanteau of "simultaneous broadcast") is the broadcasting of programs or events across more than one resolution, bitrate or medium, or more than one service on the same medium, at exactly the same time (that is, simultaneously). For example, BBC Radio 4 is simulcast on both FM and DAB. Likewise, the BBC's Prom concerts were formerly simulcast on both BBC Radio 3 and BBC Television. Another application is the transmission of the original-language soundtrack of movies or TV series over local or Internet radio, with the television broadcast having been dubbed into a local language. Yet another is when a sports game, such as Super Bowl LVIII, is simulcast on multiple television networks at the same time. In the case of Super Bowl LVIII, the game's main broadcast channel was CBS, but viewers could watch it on other CBS-owned television channels or streaming services as well; Nickelodeon and Paramount+ showed the English-language broadcast, while Univision showed the same visual but had Spanish-language broadcasters for its audio.

==Early radio simulcasts== Before launching stereo radio, experiments were conducted by transmitting left and right channels on different radio channels. The earliest record found was a broadcast by the BBC in 1926 of a Halle Orchestra concert from Manchester, using the wavelengths of the regional stations and Daventry.