Editing Greenwich Time Signal (section)

==History==
[[File:Greenwich Time Signal1970.jpg|thumb|right|The machine used to generate the pips in 1970]]
The pips have been broadcast daily since 5 February 1924,<ref name="bbchist">{{citation
|url=http://news.bbc.co.uk/1/hi/sci/tech/271319.stm
|publisher=[[BBC News]]
|title=Sci/Tech – Six pip salute
|date=5 February 1999
|access-date=23 April 2009
}}</ref>
and were the idea of the [[Astronomer Royal]], Sir [[Frank Watson Dyson]], and the head of the BBC, [[John Reith, 1st Baron Reith|John Reith]] who commissioned Marconi / Siemens in [[Charlton, London|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 [[pendulum|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.<ref name="bbchist"/>

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&nbsp;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 [[2012 Summer Olympics|London 2012 Olympics]] during the [[2008 Summer Olympics closing ceremony|Beijing 2008 Olympics closing ceremony]].<ref>{{cite news |title=Baton Passed to London for 2012 |first=Peter | last=Simpson |url=http://olympics.scmp.com/Article.aspx?id=3411&section=latestnews |newspaper=South China Morning Post |date=25 August 2008 |access-date=24 September 2011 |archive-url=https://web.archive.org/web/20120322024520/http://olympics.scmp.com/Article.aspx?id=3411&section=latestnews |archive-date=22 March 2012 }}</ref>

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 (BBC Radio 4)|Today]]'' programme broadcast a sequence that included a re-working of the Happy Birthday melody using the GTS as its base sound.<ref>{{cite web|url=https://www.bbc.co.uk/programmes/p01rqqkn|last=Lister|first=Charles|title=The 'time pips' at 90|date=5 February 2014|access-date=30 April 2016}}</ref>