In the case of television stations, this usually entails the making of an announcement to inform the viewer that the station is about to go off-air, the playing, in many cases, of the appropriate national anthem(s), the displaying of a test pattern, and/or the cutting of the carrier signal. Generally after the carrier signal is cut the viewer only sees static as the transmitter has been shut off. However depending on environmental factors those who are watching the station over the air may see programming from more distant television stations operating on the same frequency.
The practice varies from country to country, and from station to station. Most frequently, the sign-off happens at some time between midnight and 1:30 a.m.
Since the early 1990s, sign-offs have become increasingly rare in developed countries, as most now feature 24-hour networks that air content at all hours of the day and night; in many areas, the time during which a station was formerly off air has now been assigned to the broadcasting of infomercials. However, sign-offs still occur at some television stations in the United States (mostly low-power, UHF, or small-market stations) at the weekend or during routine transmitter maintenance requiring a shut-down (as of late, for instance, for HDTV), and more often in Canada. In Canada however, the CBC did away with sign-offs in favour of 24-hour programming in October 2006.
Some stations that sign off over-the-air continue to feed local cable companies' programming via a fiber optic direct line to the cable company during the time of sign-off; usually this consists of either the station's regular schedule, or an unadulterated network feed of the network's overnight programming without local advertising, such as the case of WKTV. Some stations that have their own weather departments will display an image of their weather radar with a summary of the forecast for the local area.
Many stations replaced the test pattern with their own station logos.
At some stations, a weather forecast and/or a pre-taped inspirational message (also known as a "sermonette") precedes the sign-off sequence.
In the past, many television stations also precede the sign-off or sermonette with a newscast. Until the early 1980s, it generally consisted of an announcer reading the news headlines, plus sports scores and a weather forecast, over a slide identifying it as a newscast; some stations also presented a brief, on-camera newscast, either pre-recorded with the 10PM or 11PM news team, or live with another anchor. Starting in the 1980s, many stations replaced this brief newscast with a taped replay of the 10PM or 11PM newscast, however this has become less common in the 2000's.
According to FCC regulations, however, stations are only required to merely identify themselves before leaving the air. This means stations are to announce their calls, city of license and channel number. Many stations did most or all of the above as a common courtesy.
In many instances today, signing off a station does not mean physically shutting off the transmission source. Often, a test pattern will appear or a "live scan" of the station's weather radar will remain on during the off-air hours. In the latter instance, the audio of a local radio station or instrumental music sometimes plays in the over the audio.
Some PBS member stations, such as KAKM, WKAR-TV, WYIN and WMFE-TV, close down its analog and/or digital signals at a certain hour each day, generally at 12 Midnight or 1AM. However, its overnight programming, usually from the national PBS feed, is still fed overnight to most cable and satellite providers. In most cases, this is due to budget constraints that prohibit the continual operation of the aerial signals. Some of the PBS stations that sign off regularly show an astronomy program, Jack Horkheimer: Star Gazer, as the last program of the day, before closing down.
An up-to-date listing of full-power American television stations that still sign off at some point during their broadcast week can be seen here
Fox40 KTXL did this for saturdays until 4kidsTV took over. & still does
A few stations that still sign off either each night or at some point each week include KAPP-TV, KVEW, KLEW, KSNW (and its satellites, weekends only), WKTV, WWNY, WMFE-TV, WWTI, WTOL-TV, KX Television (all 4 stations), KSMQ, WQPT, WHBF, KLKN, KCAU, WOI-TV, KEYC, KEVN, KNBN, KGIN-TV, KHAS-TV, KNOP, WOAY-TV, KVRR (and its satellites), KVLY-TV, KXJB, ABC West (all stations), KSL-TV, KTBS-TV, KCRG-TV, WJFW-TV, WTKR, WMBD-TV, WFRV-TV, WMSN-TV, WPRI-TV, WLNE-TV, WLRN-TV, WVCY-TV, WFMJ-TV (only on weekends), WDAM-TV, WUTV-TV, WWLP-TV, WNYO-TV, KQDS-TV, KUTV, KCOY, KHSL-TV, KRCR-TV, WVVA-TV, WTVH-TV, KNVN, KXLY-TV, KREM-TV, WLUC-TV, KIRO-TV and WTTV(only on Mondays).
A full night-time closedown sequence on British television would typically contain information about the following day's schedule, perhaps a local weather forecast and/or a news update, possibly a Public Information Film and finally a look at the station clock.
On BBC One, the sequence was just that - tomorrow evening's schedule, the weather, a Public Information Film but a PIF was only shown four nights a week, and finally the clock which led straight into a rendition of the National Anthem "God Save the Queen", played out over the ident. In BBC2 things were much simpler with the closedown routine just being a run through tomorrow evening and the station clock. BBC2 never closed with the National Anthem and the clock just faded to black. Channel 4 closed down with the clock and a play-out of the station ident before fading to black and after a minute or so the Channel 4 testcard appeared. Channel 4 was the only TV station to show the testcard at closedown as the BBC just radiated tone for ten minutes after closedown before the transmitters then started shutting up shop for the night.
The ITV regions mostly played the National Anthem over scenes of the Royal Family, although Wales and West of England region HTV played Hen Wlad Fy Nhadau in addition to God Save the Queen (with scenes of the flag changing to indicate the end of one anthem and the start of the other). ATV, Central's predecessor, used a version of the National Anthem played on a church organ over the station clock, eschewing the traditional band arrangements used by other broadcasters.
Some stations didn't use a National Anthem at all: the London weekday, Midlands (1982-), Scottish/English Border, Yorkshire & North-West regions. Thames chose to play popular or instrumental music over their clock, Granada played their station theme over the clock, then a minute into the music, they would fade to the Granada ident, Border and Yorkshire simply "faded out" to black, Scottish Television showed us the schedules for the next day whilst their electrical theme tune played, and in Central's case a "Good Night" caption over the station theme.
Westward Television and their successors, Television South West also used the Shipping Forecast as part of the closedown sequence, and occasionally, just before the transmitter was switched off, they liked to show short clips of Loeki de Leeuw, a cartoon lion whose adventures had bookended the advert breaks on Dutch television since the early Seventies.
Two popular items in British culture were inspired by the early years of television; firstly, the phrase "Don't forget to switch off your television set", a warning typically spoken by the station announcer which took place over a blank screen, often after several seconds of dead air, prior to the transmitter being switched off; and secondly the "little white dot", a phosphor trace which lingered on the screen as the power faded, diminishing in size until it became invisible.
The ITV regions gradually switched to 24-hour television between 1986 and 1988, under a directive issued by the Independent Broadcasting Authority. Yorkshire Television was first to go round the clock, initially showing programmes from the satellite station Music Box, until Music Box closed down. During 1987 Thames/LWT, TVS and Anglia went 24/7 and the other regions slowly followed suit during the first half of the following year. By the start of September 1988 the last regions went 24 hours apart from Ulster Television which didn't start round-the-clock broadcasting until a bit later. Some overnight programming slots were filled with teletext information pages including Jobfinder, which some regions adopted and others didn't, and, since 1998, ITV Nightscreen. The temporary suspension of ITV1's overnight gaming shows in March 2007 forced ITV1 to schedule Nightscreen in continuous blocks of up to almost three hours until the start of the ITV Morning News.
BBC One's last closedown took place on 8 November 1997. BBC News 24 has filled the early hours since but in recent years the time available for News 24 has been increasingly curtailed by programmes from the Sign Zone.
This means BBC Two is the last national British terrestrial channel to still sign off at night, but only during times of the year (or times of the week) when BBC Learning Zone is off the air. This currently includes the Christmas holiday and Friday, Saturday, Sunday nights. Pages from Ceefax fill the gap in broadcasting hours. As of March 2007, there has been a trend for BBC Two to expand its overnight hours during weekends, sometimes to as late as 5:05am, leading to speculation that BBC Two's closedowns may soon be consigned to history.
S4C, the Welsh-language channel, is the only UK terrestrial channel which continues to close down every night (though generally only for around 90 minutes between approximately 4:30 and 6.00 in the early morning). Originally, for some 10 minutes after closedown and 10 minutes before start-up, a series of still "slides" were presented with traditional music. The slides included TV listings and information, competitions, etc. This service had no official name but was commonly known as S4C Closedown Screen. In recent days, however, S4C broadcasts just a test tone and black level. The digital service S4C Digidol (S4C Digital) closes down around midnight on most evenings with a weather forecast and sign off voiced by the duty announcer.
The same affiliate's sign-off in the 1980s featured a cartoon music video sendoff featuring cartoon nudity and sights of Australia played over Good Night by The Beatles, the kangaroo clip played over a brief programming announcement, followed by a music video of a band playing an abridged version of "Advance Australia Fair", then a test pattern. This sign-off is viewable here ATN-7 went 24/7 sometime in the late 80's, putting an end to this infamous sign-off sequence.New Zealand, from 1981, Television New Zealand's Television One played a cartoon known as the Goodnight Kiwi, showing a kiwi stop broadcasting in his TV Station for the night, turning out the light, then he climbs up the stairs to the top floor with the transmitter, riding an elevator to the top of the transmitter, and going to bed in a satellite dish. The cartoon closes up with the words "Goodnight from Television New Zealand". The close was eventually used on both TV1 and TV2, of varying lengths -- 1 minute on TV1 and 2 minutes on TV2. This video may be viewable on YouTube
An alternate version shown on the second channel, TV2 (formerly South Pacific Television) Showing The Cartoon beginning normal but ending with the Kiwi going to bed inside a television camera then closes up with the kiwi shutting the side flaps of the camera then the South Pacific Television (now called TV2) logo would appear as the music faded out. It was popular with children, particularly Television One's animation.
In October 1994, TVNZ began 24-hour broadcasting, marking the disappearance of the Goodnight Kiwi from New Zealand television screens.
In September 2007, The Kiwi close was adopted by TVNZ 6.
In radio broadcasting, several major broadcasters do not practise closedowns these days. Those incluse MBC (nationwide commercial), CBS (Protestant Christian), and SBS (metropolitan commercial); they deliver radio broadcasts 24 hours a day. The Seoul's transport radio, TBS on 95.1 MHz, also runs a 24-hour broadcast. Even though they do not carry out off-air closedowns, they play the national anthem approximately at 5.00 am. The EBS (on 104.5 MHz in Seoul) and certain religious channels such as BBS (Buddhist) and PBS (Catholic) carry out closedowns from 2.00 am to 5.00 am. The KBS is quite unique. Some of the KBS radio channels including KBS Radio 1, 1FM, and 2FM are delivered 24 hours a day. On the other channels, however, closedowns still remain in place. KBS Radio 2 and 3 close down at 3.00 am and they sign on 5.00 am. KBS Radio Social Education 1 on 972 and 1134 kHz has a different closedown period. Its closedown is from 9.00 am to 1.00 pm.
In addition, an evening prayer (ex. AMEN by Sr. Gemma de la Cruz) may be said and the Philippine national anthem is played before it is replaced by a SMPTE test pattern with a black bar telling the name of the station (for ABS-CBN:ABS-CBN CH. 2; for GMA Network: GMA NETWORK TOC) or the station logo in the middle of the test card, like what Associated Broadcasting Company does. After a few seconds, it goes to static for regional stations while in cable, it shows a picture of the station.
Some cable channels don't operate 24 hours a day, mostly those which are owned by ABS-CBN such as CinemaOne Global, Knowledge Channel and Lifestyle Network, and is replaced with an advertisement showing the product, "a reason to go to sleep" and the time when the network will go back on air. On the other hand, some channels, particularly those that have block-time agreements with Solar Entertainment go off the air overnight on terrestrial television (households without cable) but actually continue to broadcast 24 hours on households with cable television.
During Holy Week, particularly Holy Thursday, Good Friday and Black Saturday, most terrestrial stations remain signed-off during the entire day. ABS-CBN signs on at noon. GMA Network signs on at 9:30 AM with some cartoons as their first program, the only station to do such. Associated Broadcasting Company signs on in the afternoon, sometimes they are not on. IBC-13 signs on in the afternoon, sometimes, even in the early evening hours.
Since ABC-5 has been rebranded as TV5, TV5 no longer sign-off and operates 24 hours a day, except for the provincial relay stations which sign-off. It also plays All Hot Music in the overnight hours. Net 25 and GEM TV would go off the air overnight on terrestrial television. It also remains sign-on in an overnight hours on households with cable television after it shows a test card and the terrestrial television will go to static.
As with television, radio stations that sign off are only required to announce their calls, frequency and city of license -- all other items are optional.
In the UK, BBC Radio 4 does "close down" in a sense. While they do not produce any original programming during their "Off-air" hours, audio from the BBC World Service is provided. BBC Asian Network also has an off-hours simulcast -- in this case, with BBC Radio Five Live.