Graph of the six pips

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 kHz 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, 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. No time signal is broadcast at 10:00 on Sundays, before the omnibus edition of The Archers. 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. From 2000 to 2008 BBC Radio 5 live used the pips weekdays at 06:00

BBC Radio 3 and BBC Radio 5 Live do not currently 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-IRIG and pre-NTP time transfer and transmission system, the pips have been a great technological success. In modern times, however, time can be transferred to systems with CPUs and operating systems by using BCD or some Unix Time variant.

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 2 and 8 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 machine used to generate the pips in 1970

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]

Crashing the pips

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" ring-tone 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.

Technical problems

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]

Similar time signals elsewhere

This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (August 2015) (Learn how and when to remove this template message)

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.

See also


  1. ^ McIlroy, Jim (Spring 1990). "Network Radio: New Time and Frequency distribution system" (pdf). Eng Inf (40). BBC ETD. Archived (PDF) from the original on 12 February 2024. Retrieved 12 February 2024.
  2. ^ "The Greenwich Time Service". Retrieved 7 February 2024.
  3. ^ "What's the time?". Astronomy & Time. Royal Museums Greenwich. Archived from the original on 22 February 2014. Retrieved 5 February 2014.
  4. ^ "Leap second: Keeper of the pips". BBC News. 30 December 2008. Retrieved 5 February 2014.
  5. ^ "The comforting tone of the hourly radio pips". BBC News (Magazine Monitor). 5 February 2014. Retrieved 5 February 2014.
  6. ^ "Leap years and leap seconds". Royal Museums Greenwich. Archived from the original on 22 February 2014.
  7. ^ "Adjusting after a 'long' weekend at the Royal Observatory – Precision clocks and the leap second". Royal Museums Greenwich. Archived from the original on 22 February 2014. Retrieved 5 February 2014.
  8. ^ "Greenwich Time Signal - the 'pips'". Retrieved 3 March 2023.
  9. ^ a b Sci/Tech – Six pip salute, BBC News, 5 February 1999, retrieved 23 April 2009
  10. ^ Simpson, Peter (25 August 2008). "Baton Passed to London for 2012". South China Morning Post. Archived from the original on 22 March 2012. Retrieved 24 September 2011.
  11. ^ Lister, Charles (5 February 2014). "The 'time pips' at 90". Retrieved 30 April 2016.
  12. ^ Tom Leonard (28 February 2002). "Pip, pip! Woman of Today is gone tomorrow". The Daily Telegraph. Retrieved 18 November 2012.
  13. ^ "The Radio 4 Pips – How you download the pips". Today Programme. BBC News. March 2005. Retrieved 18 November 2012.
  14. ^ 'Pips' slip in BBC radio error, BBC News, 17 September 2008, retrieved 23 April 2009
  15. ^ a b Denis Nowlan (1 June 2011). "What happened to the Radio 4 pips?". Radio 4 and 4 Extra Blog. BBC. Retrieved 2 June 2011.
  16. ^ Harry Wallop (31 May 2011). "Radio 4's pips die". The Telegraph. Archived from the original on 21 April 2013. Retrieved 31 May 2011.
  17. ^ "The Pips return from a 3 hour break" Radio Today 31 May 2011 Retrieved 31 May 2011.
  18. ^ Archived at Ghostarchive and the Wayback Machine: ABC Radio incoming News sound, retrieved 3 April 2018
  19. ^ "'Irrelevant and irritating': The familiar beeps heard every hour to disappear from radio broadcasts". ABC News. 23 November 2023. Retrieved 23 November 2023.
  20. ^ "Goodbye pips!". ABC listen. 29 October 2023. Retrieved 23 November 2023.
  21. ^ Archived at Ghostarchive and the Wayback Machine: "Como surgiu o sinal da Atlântida?". YouTube (in Brazilian Portuguese). Retrieved 2 May 2021.
  22. ^ Taekema, Dan (10 October 2023). "The end of the long dash: CBC stops broadcasting official 1 p.m. time signal". CBC News. Retrieved 10 October 2023.
  23. ^ "Yleisradion aikamerkki on radioklassikko" (in Finnish). 7 July 2008. Retrieved 14 August 2022.
  24. ^ "Time Synchronization with Hong Kong Time System". Hong Kong Observatory. Retrieved 29 September 2017.
  25. ^ Archived at Ghostarchive and the Wayback Machine: "תאגיד השידור הציבורי "כאן"- אותות הפתיחה והסיום של החדשות ברדיו". YouTube. Retrieved 22 May 2017.
  26. ^ "לראשונה מקום המדינה: שינוי היסטורי במהדורות כאן רשת ב" [For the first time since the establishment of the state: a historical change in the Kan Reshet Bet news report]. Kan News (in Hebrew). Israel. 3 September 2023. Retrieved 3 September 2023.
  27. ^ Archived at Ghostarchive and the Wayback Machine: "時報(TV Clock)". YouTube. Retrieved 29 April 2016.
  28. ^ "NHK 1987年 ニュースOP集". YouTube. Archived from the original on 2 February 2019. Retrieved 29 April 2016.
  29. ^ Archived at Ghostarchive and the Wayback Machine: "昭和から平成への変わり目". YouTube. Retrieved 29 April 2016.
  30. ^ Vanaf vandaag: vernieuwde 'pips' op NPO Radio 1 (in Dutch), retrieved 11 November 2019
  31. ^ Russia - Channel One - Vremya («Время») - Intro/Outro (Russia Day - 12/06/2022), retrieved 17 December 2022