Simulcast (a portmanteau of simultaneous broadcast) is the broadcasting of programs or events across more than one medium, or more than one service on the same medium, at exactly the same time (that is, simultaneously). For example, Absolute Radio is simulcast on both AM and on satellite radio. 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.
Before launching stereo radio, experiments were conducted by transmitting the left and right channels on different radio channels. The earliest record found was broadcast by the BBC in 1926 of a Halle Orchestra concert from Manchester, using the wavelengths of the regional stations and Daventry.
In its earliest days, the BBC often transmitted the same program on the "National Service" and the "Regional Network".
The early use of the word "simulcast" is from 1925.
Between 1990 and 1994 the BBC broadcast a channel of entertainment (Radio 5) which offered a wide range of simulcasts, taking programs from the BBC World Service and Radio 1, 2, 3 and 4 for simultaneous broadcast.
Before stereo TV sound transmission was possible, simulcasting on TV and radio was a method of effectively transmitting "stereo" sound to music TV broadcasts. The band Grateful Dead and their concert "Great Canadian Train Ride" in 1970 was the first TV broadcast of a live concert with FM simulcast. In the 1970s WPXI in Pittsburgh broadcast a live Boz Scaggs performance which had the audio simultaneously broadcast on two FM radio stations to create a quadrophonic sound, the first of its kind. The first such transmission in the United Kingdom was in 1975 when the BBC broadcast a recording of Van Morrison's London Rainbow Concert simultaneously on BBC2 TV and Radio 2 (see It's Too Late to Stop Now).
Similarly, in the 1980s, before Multichannel Television Sound or home theater was commonplace in American households, broadcasters would air a high fidelity version of a television program's audio portion over FM stereo simultaneous with the television broadcast. PBS stations were the most likely to use this technique, especially when airing a live concert. It was also a way of allowing MTV and similar music channels to run stereo sound through the cable-TV network. This method required a stereo FM transmitter modulating MTV's stereo soundtrack through the cable-TV network, and customers connecting their FM receiver's antenna input to the cable-TV outlet. They would then tune the FM receiver to the specified frequency that would be published in documentation supplied by the cable-TV provider.
With the introduction of commercial FM stations in Australia in July 1980, commercial TV channels began simulcasting some music-based programs with the new commercial FM stations and continued to do so into the early 1990s. These were initially rock-based programs, such as late-night music video shows and rock concerts, but later included some major rock musicals such as The Rocky Horror Picture Show and The Blues Brothers when they first aired on TV. During the mid-1980s, the final Australian concert of several major rock artists such as Dire Straits was simulcast live on a commercial TV and FM station. The ABC also simulcast some programs on ABC Television and ABC FM, including the final concert of Elton John with the Melbourne Symphony Orchestra.
The first CABLE TV concert simulcast was Frank Zappa's Halloween show (October 31, 1981), live from NYC's Palladium and shown on MTV with the audio-only portion simulcast over FM's new "Starfleet Radio" network. Engineered by Mark G. Pinske with the UMRK mobile recording truck. A later, notable application for simulcasting in this context was the Live Aid telethon concert that was broadcast around the world on July 13, 1985. Most destinations where this concert was broadcast had the concert simulcast by at least one TV network and at least one of the local FM stations.
Most stereo-capable video recorders made through the 1980s and early 1990s had a "simulcast" recording mode where they recorded video signals from the built-in TV tuner and audio signals from the VCR's audio line-in connectors. This was to allow one to connect a stereo FM tuner that is tuned to the simulcast frequency to the VCR's audio input in order to record the stereo sound of a TV program that would otherwise be recorded in mono. The function was primarily necessary with stereo VCRs that didn't have a stereo TV tuner or were operated in areas where stereo TV broadcasting wasn't in place. This was typically selected through the user setting the input selector to "Simulcast" or "Radio" mode or, in the case of some jvc units, the user setting another "audio input" switch from "TV" or "Tuner" to "Line".
In the mid to late 1990s, video game developer Nintendo utilized simulcasting to provide enhanced orchestral scoring and voice-acting for the first-ever "integrated radio-games" – its Satellaview video games. Whereas digital game data was broadcast to the Satellaview unit to provide the basic game and game sounds, Nintendo's partner, satellite radio company St.GIGA, simultaneously broadcast the musical and vocal portion of the game via radio. These two streams were combined at the Satellaview to provide a unified audiotrack analogous to stereo.
The term "simulcast" (describing simultaneous radio/television broadcast) was coined in 1948 by a press agent at WCAU-TV, Philadelphia. NBC and CBS had begun broadcasting a few programs both to their established nationwide radio audience and to the much smaller—though steadily-growing—television audience. NBC's "Voice of Firestone" is sometimes mentioned in this regard, but NBC's "Voice of Firestone Televues" program, reaching a small Eastern audience beginning in 1943, was a TV-only show, distinct from the radio "Voice of Firestone" broadcasts. Actual TV-AM radio simulcasts of the very same "Voice of Firestone" program began only on 5 September 1949. A documented candidate for first true simulcast may well be NBC's "We the People." Toscanini's NBC Symphony performance of 15 March 1952 is perhaps the first instance of radio/TV simulcasting of a concert, predating the much-heralded rock concert simulcasts beginning in the 1980s. It could, however, be argued that these Toscanini presentations--with admission controlled by NBC, as with all its programming--were no more "public concerts" than NBC's "Voice of Firestone" broadcasts beginning in 1949, or its "Band of America" programs, which were simulcast starting 17 October 1949. Likewise Toscanini's simulcast NBC presentation of two acts of Verdi's "Aida" on 3 April 1949.
Presently, in the United States, simulcast most often refers to the practice of offering the same programming on an FM and AM station owned by the same entity, in order to cut costs. With the advent of solid-state AM transmitters and computers, it has become very easy for AM stations to broadcast a different format without additional cost; therefore, simulcast between FM/AM combinations are rarely heard today outside of rural areas, and in urban areas, where often the talk or all-news radio format of an AM station is simulcast on FM, mainly for the convenience of office buildings in urban cores which easily block AM signals.
During apartheid in South Africa, many foreign programs on SABC television were dubbed in Afrikaans. The original soundtrack, usually in English, but sometimes in German or Dutch was available on the Radio 2000 service. This could be selected using a button labeled simulcast on many televisions manufactured before 1995.
Radio programs have been simulcast on television since the invention thereof, however, as of recent, perhaps the most visible example of radio shows on television is The Howard Stern Show, which currently airs on Sirius Satellite Radio as well as Howard TV. Another prominent radio show that was simulcast on television is Imus in the Morning, which until the simulcast ended in 2015, aired throughout the years on MSNBC, RFD-TV, and Fox Business Network, in addition to its radio broadcast distributed by Citadel Media. Multiple sports talk radio shows, including Mike & Mike, The Herd with Colin Cowherd and Boomer and Carton also are carried on television, saving those networks the burden of having to air encores of sporting events or other paid sports programming which may draw lower audiences.
In professional wrestling, a simulcast happened on March 26, 2001, between WWF Raw is War and WCW Monday Nitro upon WWE's purchase of WCW's assets to merge the storylines of the two wrestling promotions, which was the last episode of Monday Nitro.
In another case, popular programs will be aired simultaneously on different services in adjacent countries, such as The Simpsons, airing Sunday evenings at 8:00 p.m. (Eastern and Pacific times) on both Fox in the United States and Global in Canada. "Simulcast" is often a colloquial term for the related Canadian practice of simultaneous substitution (simsub).
Simulcasts are also used for the purposes of television ratings, mainly with awards ceremonies such as the MTV Video Music Awards and the nickelodeon Kids' Choice Awards where the ceremony airs on other sister channels in the same corporate family. These allow a bulk rating number to compete which allows for more homes to be calculated in a final rating, along with removing any in-house competition, with each of the networks carrying the same ceremony and same advertising. Another example is a "roadblock strategy", where a family of networks will air the premiere of a new series, music video or other events such as a telethon at the same time to maximize their audiences. During major breaking news events, a simulcast of the Fox News Channel is aired on the Fox broadcast network and Fox Business Network.
"Live Simulcast" is also used throughout South America for real-time live broadcasting from the USA, where it differs from just live broadcasting in that, on the former case, the event is being broadcast live while it is happening in real-time (e.g. the NFL games), while, the latter, a show may be a live recording but not necessarily being broadcast in real-time of when the event took place (e.g. a live concert recording). Yet, local live productions (soccer games, for instance) being broadcast in real-time in South America are often just called live, without the use of the word simulcast.