The Greenwich Time Signal (GTS), popularly known as the pips, is a series of six short tones (or "pips") broadcast at one-second intervals by many BBC Radio stations to mark the precise start of each hour. The pips were introduced in 1924, generated by the Royal Observatory, Greenwich, and from 1990 were generated by the BBC in London. [1] The broadcast pips replaced an electrical time coordination system based on the railway telegraph network, which itself was an extension of the mechanical time balls in Portsmouth (1829) and later Greenwich (1833), which enabled navigators aboard ships moored in those places to set their chronometers for the determination of longitude on voyages. [2]
There are six pips (short beeps) in total, which occur on each of the 5 seconds leading up to the hour and on the hour itself. Each pip is a 1 k Hz tone (about a fifth of a semitone above musical B5) the first five of which last a tenth of a second each, while the final pip lasts half a second. The actual moment when the hour changes – the "on-time marker" – is at the very beginning of the last pip. [3]
When a leap second occurs (exactly one second before midnight UTC), it is indicated by a seventh pip. In this case the first pip occurs at 23:59:55 (as usual) and there is a sixth short pip at 23:59:60 (the leap second) followed by the long pip at 00:00:00. [4] The possibility of an extra pip for the leap second thus justifies the final pip being longer than the others, so that it is always clear which pip is on the hour. Before leap seconds were conceived in 1972, the final pip was the same length as the others. [5] Although "negative" leap seconds can also be used to make the year shorter, this has never happened in practice. [6] [7]
Although normally broadcast only on the hour by BBC domestic radio, BBC World Service uses the signal at other times as well. The signal is generated at each quarter-hour and has on occasion been broadcast in error. [8]
The pips are available to BBC radio stations every fifteen minutes, but, except in rare cases, they are only broadcast on the hour, usually before news bulletins or news programmes. Normally, BBC Radio 4 broadcast the pips every hour except at 18:00 and 00:00 (at the start of the Six O'Clock News and Midnight News respectively), and at 22:00 on Sundays (at the start of the Westminster Hour ) when they are replaced by the striking of Big Ben at the Palace of Westminster. On BBC Radio 2, the pips are used at 07:00, 08:00 and 17:00 on weekdays, at 07:00 and 08:00 on Saturdays and at 08:00 and 09:00 on Sundays.
The pips were used on BBC Radio 1 during The Chris Moyles Show at 06:30 just after the news, 09:00 as part of the "Tedious Link" feature, 10:00 (at the end of the show) and often before Newsbeat . As most stations only air the pips on the hour, The Chris Moyles Show was the only show where the pips were broadcast on the half-hour. Chris Moyles continues to use the pips at the beginning of his show on Radio X. The pips were previously used at 19:00 on Saturday evenings at the start of Radio 1's 12-hour simulcast with digital station BBC Radio 1Xtra. The pips were also used on Radio 6 Music for a rare occurrence. It took place between 2009 and 2011 on weekdays and the pips were played at 10:00 (end of the breakfast show) and at 19:00 (end of the drive show). On Remembrance Day and Remembrance Sunday, Radio 4 uses the pips at 10:59:55 to mark the start of the two minutes silence and again at 11:01:55 to mark the end.
BBC Radio 5 Live broadcast the pips at 06:00 between 2000 and 2008.
BBC Radio 3 and BBC Radio 5 Live does not broadcast the pips.
The BBC World Service broadcasts the pips every hour.
Pips were also heard on many BBC Local Radio stations until the introduction of a new presentation package in 2020. A rare quarter-hour Greenwich Time Signal was heard at 05:15 weekdays on Wally Webb's programme on local radio in the east of England until it ended in March 2020, as part of his "synchronised cup of tea" feature.
In 1999, pip-like sounds were incorporated into the themes written by composer David Lowe to introduce BBC Television News programmes. They are still used today on BBC One, BBC Two, BBC World News and BBC News.
The BBC does not allow the pips to be broadcast except as a time signal. Radio plays and comedies which have fictional news programmes use various methods to avoid playing the full six pips, ranging from simply fading in the pips to a version played on On the Hour in which the sound was made into a small tune between the pips. The News Quiz also featured a special Christmas pantomime edition where the pips went "missing", and the problem was avoided there by only playing individual pips. The 2012 project Radio Reunited used the pips to commemorate 90 years of BBC Radio.
The pips for national radio stations and some local radio stations are timed relative to UTC, from an atomic clock in the basement of Broadcasting House synchronised with the National Physical Laboratory's Time from NPL and GPS. On other stations, the pips are generated locally from a GPS-synchronised clock. The broadcast pips usefulness for time calibration is diminished by the time lags involved in digital broadcasting.
The BBC compensates for the time delay in both broadcasting and receiving equipment, as well as the time for the actual transmission. The pips are timed so that they are accurately received on long wave as far as 160 kilometres (100 mi) from the Droitwich AM transmitter, which is the distance to Central London.
As a pre-digital time transfer and transmission system, the pips have been a great technological success. In modern times, however, time can be transferred using IRIG and pre-NTP.
Newer digital broadcasting methods have introduced even greater problems for the accuracy of use of the pips. On digital platforms such as DVB, DAB, satellite and the Internet, the pips — although generated accurately — are not heard by the listener exactly on the hour. The encoding and decoding of the digital signal causes a delay, of usually between two and eight seconds. In the case of satellite broadcasting, the travel time of the signal to and from the satellite adds about another 0.25 seconds.
The pips have been broadcast daily since 5 February 1924, [9] and were the idea of the Astronomer Royal, Sir Frank Watson Dyson, and the head of the BBC, John Reith who commissioned Marconi / Siemens in Charlton, close to Greenwich, to create the signal. The company gave the project to an 18-year-old engineer, Harry Lampen Edwards, who was seconded to the Observatory. The pips were originally controlled by two mechanical clocks located in the Royal Greenwich Observatory that had electrical contacts attached to their pendula. Two clocks were used in case of a breakdown of one. These sent a signal each second to the BBC, which converted them to the audible oscillatory tone broadcast. [9]
The Royal Greenwich Observatory moved to Herstmonceux Castle in 1957 and the GTS equipment followed a few years later in the form of an electronic clock. Reliability was improved by renting two lines for the service between Herstmonceux and the BBC, with a changeover between the two at Broadcasting House if the main line became disconnected.
The tone sent on the lines was inverted: the signal sent to the BBC was a steady 1 kHz tone when no pip was required, and no tone when a pip should be sounded. This let faults on the line be detected immediately by automated monitoring for loss of audio.
The Greenwich Time Signal was the first sound heard in the handover to the London 2012 Olympics during the Beijing 2008 Olympics closing ceremony. [10]
The pips were also broadcast by the BBC Television Service, but this practice was discontinued by the 1960s.
To celebrate the 90th birthday of the pips on 5 February 2014, the Today programme broadcast a sequence that included a re-working of the Happy Birthday melody using the GTS as its base sound. [11]
The BBC discourages any other sound being broadcast at the same time as the pips; doing so is commonly known as "crashing the pips". This was most often referred to on Terry Wogan's Radio 2 Breakfast show, although usually only in jest since the actual event happened rarely. [12] Different BBC Radio stations approach this issue differently. Radio 1 and Radio 2 generally take a relaxed approach with the pips, usually playing them over the closing seconds of a song or a jingle "bed" (background music from a jingle), followed by their respective news jingles. Many BBC local radio stations also played the pips over the station's jingle before the 2020 rebrand. BBC Radio 4 is stricter, as it is an almost entirely speech-based network.
As a contribution to Comic Relief's 2005 Red Nose Day, the BBC developed a "pips" ringtone which could be downloaded. [13]
Bill Bailey's BBC Rave includes the BBC News theme, which incorporates a variant of the pips (though not actually broadcast exactly on the hour). The footage can be seen on his DVD Part Troll.
In the late 1980s Radio 1 featured the pips played over a station jingle during Jakki Brambles' early show and Simon Mayo's breakfast show. This was not strictly "crashing the pips" as they were not intended to be used as an accurate time signal.
At 8 am on 17 September 2008, to the surprise of John Humphrys, the day's main presenter on the Today programme, and Johnnie Walker, who was standing in for Terry Wogan on Radio 2, the pips went "adrift" by six seconds, and broadcast seven pips rather than six. This was traced to a problem with the pip generator, which was rectified by switching it off and on again. [14] Part of Humphrys' surprise was probably because of his deliberate avoidance of crashing the pips with the help of an accurate clock in the studio.
A sudden total failure in the generation of the audio pulses that constitute the pips was experienced on 31 May 2011 and silence was unexpectedly broadcast in place of the 17:00 signal. The problem was traced to the power supply of the equipment which converts the signal from the atomic clocks into an audible signal. [15] Whilst repairs were underway the BBC elected to broadcast a "dignified silence" in place of the pips at 19:00. [16] By 19:45 the same day the power supply was repaired [15] and the 20:00 pips were broadcast as normal. [17]
Many radio broadcasters around the world use the Greenwich Time Signal, or a variant thereof, as a means to mark the start of the hour. The pips are used in both domestic and international commercial and public broadcasting. Many radio stations use six tones similar to those used by the BBC World Service; some shorten it to five, four, or three tones. On some broadcasters the final pip is of a different pitch.
Greenwich Mean Time (GMT) is the local mean time at the Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, including being calculated from noon; as a consequence, it cannot be used to specify a particular time unless a context is given. The term "GMT" is also used as one of the names for the time zone UTC+00:00 and, in UK law, is the basis for civil time in the United Kingdom.
Universal Time is a time standard based on Earth's rotation. While originally it was mean solar time at 0° longitude, precise measurements of the Sun are difficult. Therefore, UT1 is computed from a measure of the Earth's angle with respect to the International Celestial Reference Frame (ICRF), called the Earth Rotation Angle. UT1 is the same everywhere on Earth. UT1 is required to follow the relationship
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The Time from NPL is a radio signal broadcast from the Anthorn Radio Station near Anthorn, Cumbria, which serves as the United Kingdom's national time reference. The time signal is derived from three atomic clocks installed at the transmitter site, and is based on time standards maintained by the UK's National Physical Laboratory (NPL) in Teddington. The service is provided by Babcock International, under contract to the NPL. It was funded by the former Department for Business, Innovation and Skills; as of 2017 NPL Management Limited (NPLML) was owned by the Department for Business, Energy and Industrial Strategy (BEIS), and NPL operated as a public corporation.
A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day.
CHU is the call sign of a shortwave time signal radio station operated by the Institute for National Measurement Standards of the National Research Council. CHU's signal is used for continuous dissemination of official Canadian government time signals, derived from atomic clocks.
BPM is the call sign of the official short-wave time signal service of the People's Republic of China, operated by the Chinese Academy of Sciences, broadcasting from CAS's National Time Service Center in Pucheng County, Shaanxi at 34°56′55.96″N109°32′34.93″E, roughly 70 km northeast of Lintong, along with NTSC's long-wave time signal BPL on 100 kHz.
WWV is a shortwave radio station, located near Fort Collins, Colorado. It has broadcast a continuous time signal since 1945, and implements United States government frequency standards, with transmitters operating on 2.5, 5, 10, 15, and 20 MHz. WWV is operated by the U.S. National Institute of Standards and Technology (NIST), under the oversight of its Time and Frequency Division, which is part of NIST's Physical Measurement Laboratory based in Gaithersburg, Maryland.
WWVH is the callsign of the U.S. National Institute of Standards and Technology's shortwave radio time signal station located at the Pacific Missile Range Facility Barking Sands, in Kekaha, on the island of Kauai in the state of Hawaii.
WWVB is a longwave time signal radio station near Fort Collins, Colorado and is operated by the National Institute of Standards and Technology (NIST). Most radio-controlled clocks in North America use WWVB's transmissions to set the correct time.
JJY is the call sign of a low frequency time signal radio station located in Japan.
DCF77 is a German longwave time signal and standard-frequency radio station. It started service as a standard-frequency station on 1 January 1959. In June 1973 date and time information was added. Its primary and backup transmitter are located at 50°0′56″N9°00′39″E in Mainflingen, about 25 km (20 mi) south-east of Frankfurt am Main, Germany. The transmitter generates a nominal power of 50 kW, of which about 30 to 35 kW can be radiated via a T-antenna.
The National Research Council Time Signal was Canada's longest running radio program, begun 5 November 1939 until its final broadcast on 9 October 2023. Broadcast daily shortly before 13:00 Eastern Time across the CBC Radio One network, it lasted between 15 and 60 seconds, ending exactly at 13:00. During standard time, the signal was at 13:00 Eastern Standard Time and during Daylight Saving Time, the signal was at 13:00 Eastern Daylight Saving Time.
YVTO is the callsign of the official time signal from the Juan Manuel Cagigal Naval Observatory in Caracas, Venezuela. The content of YVTO's signal, which is a continuous 1 kW amplitude modulated carrier wave at 5.000 MHz, is much simpler than that broadcast by some of the other time signal stations around the world, such as WWV.
A speaking clock or talking clock is a live or recorded human voice service, usually accessed by telephone, that gives the correct time. The first telephone speaking clock service was introduced in France, in association with the Paris Observatory, on 14 February 1933.
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JN53dv is the Maidenhead grid square of an experimental shortwave time signal station in Italy. It is located in the town of Corsanico-Bargecchia near Massarosa and operated by Italcable
Pip-squeak was a radio navigation system used by the British Royal Air Force during the early part of World War II. Pip-squeak used an aircraft's voice radio set to periodically send out a 1 kHz tone which was picked up by ground-based high-frequency direction finding receivers. Using three HFDF measurements, observers could determine the location of friendly aircraft using triangulation.
A sign-on is the beginning of operations for a radio or television station, generally at the start of each day. It is the opposite of a sign-off, which is the sequence of operations involved when a radio or television station shuts down its transmitters and goes off the air for a predetermined period; generally, this occurs during the overnight hours although a broadcaster's digital specialty or sub-channels may sign-on and sign-off at significantly different times than its main channels.
In the United Kingdom, television closedowns originally took place frequently during the daytime, and sometimes for a few hours at a time. This was due initially to Government-imposed restrictions on daytime broadcasting hours, and later, budgetary constrictions. The eventual relaxation of these rules meant that afternoon closedowns ceased permanently on the ITV network in October 1972. The BBC took a long time to abandon the practice, and did not commence a full daytime service until the autumn of 1986.