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In broadcasting, local insertion is the act or capability of a broadcast television station, radio station or cable system to insert or replace part of a broadcast network feed with content unique to the local station or system. Most often this is a station identification (required by the Federal Communications Commission), but is also commonly a television commercial or sometimes a radio ad, or a weather or traffic report. A digital on-screen graphic ("dog" or "bug"), commonly a semi-transparent watermark, may also be keyed (superimposed) with a television station identification over the network feed using a character generator using genlock. In the case where several programs are carried separately from the main broadcast network, this is known as regional variation (in the United Kingdom) or a television network (in Canada and the United States).
Automated local insertion used to be triggered with in-band signaling, such as DTMF tones or sub-audible sounds (such as 25 Hz), but is now done with out-of-band signaling, such as analog signal subcarriers via communications satellite, or now more commonly via digital signals. Broadcast automation equipment can then handle these automatically. In an emergency, such as severe weather, local insertion may also occur instantly through command from another network or other source, such as the Emergency Alert System. In this case, the most urgent warning messages may interrupt without delay, while others may be worked into a normal break in programming within 15 minutes of their initial issuance.
Within individual programs
In the United States, insertion can easily be heard every evening on Delilah, a nationally-syndicated radio show, where the host does a pre-recorded station-specific voiceover played over a music bed from the network. When she says "this is Delilah", her voice (often in a slightly different tone or mood than what she has just been speaking) then says "on B98.5 FM" when heard on WSB-FM in metro Atlanta, for example. Listeners to other stations hear their own station's moniker or ID instead. Because of this slight difference in vocal quality, many syndicated radio networks suggest using only one voice for local station ID 24/7; in this way, the difference in vocal intonation is lessened.
The other more prominent example is during live sports programming carried over radio and television networks, where close to the top of the hour, the play-by-play announcer will say "we pause ten seconds for station identification; this is the (team name) (radio network branding)", or a close equivalent. On most stations it is a basic FCC station identification with the call letters and city of license relayed, while on others a quickly-read five second advertisement or program promotion is read before the identification, or a breaking news event or weather warning occurring during the event is relayed, followed by the station ID. Due to many sports rights deals for televised sports moving to regional sports networks which are not required to identify themselves under FCC guidelines, or network sports coverage where the station identification is made with an on-screen display by the local station rather than speech, this is more prominent on radio rather than television.
Local commercial (and some non-commercial) broadcast television stations also locally insert local commercial breaks during each half-hour of network programming. Television networks give their affiliates either 60, 90 or 120 seconds each half-hour (typically totaling about four minutes each hour) to run local station breaks, including station promos and advertisements for national and local area businesses (and on a few stations, local news updates (this was particularly common during the 1970s through the 1990s, especially as the 24 Hour News Source format became commonplace in the United States during the latter decade), current time and temperature information or a brief local weather forecast), over network programming. Typically, these networks air a blank feed showing the network's logo (such as with Fox, NBC and The CW) or a series of public service announcements (as with ABC and CBS), while stations air local commercials. PBS member stations also insert promos for PBS network series and locally-produced programming during promo breaks; as PBS is non-commercial, the network typically does not feature breaks during the programs themselves, instead promos are inserted in-between programs, even if the member station is carrying PBS' national network feed.
Various television morning news shows (such as Good Morning America and Today) also have a local news break for five minutes (sometimes as little as three minutes) prior to each "top" or "bottom" half-hour (:25 to :30 and :55 to :00), though the national feed continues for stations that do not wish to "break away", either because they have no news operation or because they may not air a morning newscast (for example, Ada, Oklahoma NBC affiliate KTEN does not air news cut-ins during the weekend edition of Today as the only weekend newscast on that station airs at 10 p.m., but cut-ins are shown during the weekday telecasts where Today follows a morning newscast). This also occurs with news on NPR's Morning Edition and All Things Considered, which are on during the morning and evening rush hours, respectively.
Starting in the early 1990s, some cable television systems began carrying a local insert called "Local Edition", a segment featuring local news inserts (which are produced by area television stations or local cable operators) that air at :24 and :54 minutes past the hour during HLN's rolling daytime news block, usually during the network's non-essential features news block. This has been discontinued as that network has switched to a general news/talk format.
Broadcast translators may also have local insertion, though this is very limited to identifying the repeating station's callsign and community of license separate from its parent station. In the United States, the Federal Communications Commission (FCC) also allows up to 30 seconds each hour for fundraising to keep the translator service on the air.
Local insertion is also used by cable and telephone company television providers, in which cable and telco headends insert advertisements for the cable system, promos for programs on other cable channels carried by the cable provider and commercials for local area businesses (such as car dealerships or furniture stores) at least twice each hour; unlike most commercial broadcast stations, however, cable channels often run only 60 seconds of local commercial inserts each half-hour near the end of the first or second commercial break and are aired in place of national ads or network promos that air during that given time. Direct-broadcast satellite services cannot locally insert content during commercial breaks, so viewers are either able to see ads or promos that are covered up by the local content on cable or see a DBS company's own promos.
Local insertion on cable television is used especially on The Weather Channel in the U.S. and The Weather Network/MétéoMédia in Canada, where systems like the WeatherSTAR, IntelliSTAR and PMX have been used to show local weather forecasts (known as "Local on the 8s" on The Weather Channel in the U.S.) every ten minutes, and well as the lower display line (LDL) or lower-third graphic that is shown at other times. The Weather Channel, in particular also airs barker ads during national breaks at the end of some commercials allowing its WeatherSTAR or IntelliSTAR systems to insert certain area locations for certain businesses, such as restaurants or auto rental dealers; though The Weather Channel has not done this as much in recent years as they have in the past. This only applies to the cable systems, although in the U.S. direct-broadcast satellite services have shown an LDL of the current conditions and 12-hour forecast for select major cities. This is not seen on older TVRO or "big ugly dish" systems, as this is intended as a backhaul and has very few end-users, and is used as a clean feed.
In place of the IntelliSTAR, a hyper-local form of insertion is now done on DirecTV (and possibly other DBS services), whereby the first half of the local forecast is generated by the set-top box. A "cutout" at the upper right corner of the picture allows the sponsor's advertising logo to be shown live from the main video, while a datacast on the satellite (like that which provides the electronic program guide) sends simple forecast and conditions data for the entire country every couple of minutes. Graphics are stored on the receiver, and displayed according to the forecast, which is selected by ZIP code or city according to user settings.
Additionally, starting in 2011, DirecTV users with digital video recorders will have commercials downloaded to their boxes, which will play according to their demographic information, likely commanding higher revenue from advertisers. This may eventually lead to or merge with interactive television, which may find more success on cable and telco television because of the lack of a return channel on satellite and broadcast. Internet-connected TVs may erode this barrier as well, however, with only their embedded flash memory chip necessary to hold short video clips.