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Encyclopedia > Greenwich Time Signal
Graph of the six pips

## Contents

There are six pips (short beeps) in total, which occur on the 5 seconds leading up to the hour and on the hour itself. Each pip is a 1 kHz tone which, for the five leading pips, lasts a tenth of a second, while the final pip lasts half a second. The actual moment when the hour changes is at the very beginning of the last 'long' pip. An SI prefix is a prefix that can be applied to an SI unit to form a decimal multiple (supramultiple or submultiple). ... The hertz (symbol: Hz) is the SI unit of frequency. ...

• GTS Time Signal ( file info) — play in browser (beta)
• The 6 Pips
• Problems listening to the file? See media help.

When a leap second occurs, 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. The leap second is also the explanation for the final pip being longer than the others. This is so that it is always clear which pip is on the hour, especially where there is an extra pip that some people might not be expecting. Prior to the invention of leap seconds, the final pip was the same length as the others. Image File history File links Gts_(bbc)_pips. ... Software development stages In computer programming, development stage terminology expresses how the development of a piece of software has progressed and how much further development it may require. ... A leap second is a one-second adjustment to civil time in order to keep it close to the mean solar time. ...

Although only normally broadcast on the hour, the signal is also generated at quarter-past, half-past and quarter-to every hour. It has occasionally been broadcast at these times due to operator error.

## Usage and homages

The pips are used on some BBC radio stations to mark the start of the hour. On Radio 4, at start of the 6 o'clock evening, 10pm and midnight news the pips are replaced by the chimes of Big Ben, where the first chime represents the start of the hour. In 1999, pip-like sounds were incorporated into BBC Television News by composer David Lowe. This included news on BBC ONE and later BBC NEWS 24 and BBC WORLD. The pips can be heard every hour on the BBC's worldwide radio station BBC World Service. The Clock Tower, colloquially known as Big Ben (a name that correctly refers to the main bell) Big Ben redirects here. ... 1999 (MCMXCIX) was a common year starting on Friday, and was designated the International Year of Old Farts by the Sometimes-United Nations. ... The current BBC News logo BBC News and Current Affairs is a major arm of the BBC responsible for the corporations newsgathering and production of news programmes on BBC television, radio and online. ... David Lowe is a British composer, focusing primarily on music for television. ... BBC One (or BBC1 as it was formerly styled) is the primary channel of the British Broadcasting Corporation. ... BBC News 24 is BBC News 24-hour news television channel in the UK, its international counterpart being BBC World. ... BBC World is the BBCs 24-hour international, news and information television channel, launched on January 1995. ... The BBC World Service is one of the most widely recognised international broadcasters of radio programming, transmitting in 33 languages to many parts of the world. ...

As a contribution to the 2005 Red Nose Day charity day the BBC have developed a "pips" ring-tone. For a description of the origin of the term comic relief see comic relief. ...

## History

The pips have been broadcast since February 5, 1924, and were the idea of the Astronomer Royal Sir Frank Watson Dyson and head of the BBC John Reith. The pips were originally controlled by two mechanical clocks located in the Royal Greenwich Observatory that had electrical contacts attached to the pendulums. Two clocks were used in case of a breakdown. These sent a signal each second to the BBC, who converted them to the audible oscillatory signal that is broadcast. February 5 is the 36th day of the year in the Gregorian Calendar. ... 1924 (MCMXXIV) was a leap year starting on Tuesday (link will take you to calendar). ... Astronomer Royal is a senior post in the Royal Household of the Sovereign of the United Kingdom. ... Sir Frank Watson Dyson (January 8, 1868 â€“ May 25, 1939) was an English astronomer. ... John Charles Walsham Reith, 1st Baron Reith (July 20, 1889 - June 16, 1971), later Sir John Reith (1927-), then Baron Reith (1940-) established the British tradition of independent public service broadcasting. ... Royal Observatory, Greenwich The original site of the Royal Greenwich Observatory (RGO), which was built as a workplace for the Astronomer Royal, was on a hill in Greenwich Park in Greenwich, London, overlooking the River Thames. ... Simple gravity pendulum assumes no air resistance and no friction of/at the nail/screw. ...

The signal on the line was inverted; that is, the signal sent to the BBC was "on" when no pip was required, and was pulsed "off" when a pip should be sounded. This allowed a fault on the line to be detected easily.

Today the pips for national radio stations and some local radio stations are timed relative to UTC, obtained from an atomic clock located in the basement of Broadcasting House that is synchronised with British Telecom's Rugby time signal and GPS. On other stations, the pips are generated locally from a GPS-synchronised clock. ... Atomic clock Chip-Scale Atomic Clock Unveiled by NIST An atomic clock is a type of clock that uses an atomic resonance frequency standard as its counter. ... Broadcasting House Broadcasting House is the headquarters of the BBC in London, England. ... BT Group plc (which trades as just BT, and is commonly known by its former name, British Telecom) is the privatised former British state telecommunications operator. ... The MSF time signal is a broadcast from the VLF transmitter Rugby near Rugby, Warwickshire based on time standards maintained by the British National Physical Laboratory. ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ...

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 accurate as received on long wave 160 km (about 100 miles) from the Droitwich AM transmitter, which is the distance to central London. Longwave radio frequencies are those below 500 kHz, which correspond to wavelengths longer than 600 meters. ... The Droitwich AM transmitter is a large broadcasting facility for longwave and mediumwave established in 1934 close to the village of Wychbold, near Droitwich, Worcestershire, England (grid reference SO929663). ...

Newer digital broadcasting methods have introduced even greater problems for the accuracy of the pips: on platforms which use digital compression such as DAB, digital satellite, Freeview as well as listening via the Internet; the pips are no longer exactly on the hour. The encoding and decoding of the digital signal can cause a slight delay. In the case of satellite broadcasting, the travel to and from the satellite adds a further delay of around 0.25s. Digital Audio Broadcast or DAB is a standard for digital radio broadcast developed by EUREKA as a research project for the European Union. ... MILSTAR:A communication satellite A satellite is any object that orbits another object (which is known as its primary). ... FreeView is a non-profit free-to-air digital television service planned for New Zealand. ... Look up second in Wiktionary, the free dictionary. ...

The MSF time signal is a broadcast from the VLF transmitter Rugby near Rugby, Warwickshire based on time standards maintained by the British National Physical Laboratory. ... -1... CBC Radio One is the English language news and information radio network of the publicly-owned Canadian Broadcasting Corporation. ...

Results from FactBites:

 Atomic Clock Synchronization using the WWVB time signal from Colorado (1132 words) Accurate time using Atomic Clock accuracy is available across North America using the WWVB Atomic Clock time signal transmitted from Colorado, it provides the ability to synchronize the time on computers and other electrical equipment. Greenwich Mean Time (GMT) was established as the first global time scale in 1884, and its 'atomic' equivalent, UTC, was adopted as the official time for the world in January 1972. The 60,000 Hz signal is always transmitted, but every second it is significantly reduced in power for a period of 0.2, 0.5 or 0.8 seconds: •; 0.2 seconds of reduced power means a binary zero • 0.5 seconds of reduced power is a binary one.
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