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Encyclopedia > Time signal

A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day.

These automatic signal clocks were synchronized by telegraphy before the widespread use of radio.

Contents

Automatic time signal clocks in use in 1905 to coordinate time with the United States Naval Observatory by telegraphy. ... Synchronization (or Sync) is a problem in timekeeping which requires the coordination of events to operate a system in unison. ... Telegraph and Telegram redirect here. ...

Audible and visible time signals

One sort of public time signal is, of course, a striking clock. These clocks, however, are only as good as the clockwork that activates them; they have improved substantially since the first surviving clocks from the fourteenth century. For many members of the general public, a public clock such as Big Ben was the only time standard they needed. Big Ben, the tower clock of the Palace of Westminster in London, is a famous striking clock. ... (13th century - 14th century - 15th century - more centuries) As a means of recording the passage of time, the 14th century was that century which lasted from 1301 to 1400. ... “Big Ben” redirects here. ...


When more accurate public time signals were desired for use in navigation, a number of traditional audible or visible time signals were established for the purpose of allowing navigators to check their marine chronometers. These public time signals were formerly established in many seaport cities. Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia. ... A marine chronometer is a timekeeper precise enough to be used as a portable time standard, used to determine longitude by means of celestial navigation. ... It has been suggested that this article or section be merged with Port. ...


As an example of such a signal, in Vancouver, British Columbia, a "9 o'clock gun" is still shot every night at 9 p.m.. This gun was brought to Stanley Park by the Department of Fisheries in 1894 to warn fishermen of the 6:00 p.m. Sunday closing of fishing. The 9:00 p.m. firing was later established as a time signal for the general population. The Brockton Point lighthouse keeper, William D. Jones, originally detonated a stick of dynamite until the Time Gun was installed. A similar "Noon Gun" is still shot every noon at Cape Town, South Africa. A cannon was shot at one o'clock every weekday at Liverpool, England, at the Castle in Edinburgh, Scotland, and also at Perth in Australia to establish the time. The Edinburgh "one o'clock gun" is still in operation. A cannon located at the top of Santa Lucia Hill, in Santiago, Chile, is shot every noon. In places where a cannon is used for a time signal, locals often joke that they can spot tourists because they jump in surprise while locals check their watches. In many Midwestern US cities where tornados are a common hazard, the emergency sirens are tested regularly at a specified time (such as, say, noon each Saturday); while this is not primarily intended as a time signal, locals often do check their watches when they hear it. For other uses, see Vancouver (disambiguation). ... Motto: Splendor sine occasu (Latin: Splendour without diminishment) Capital Victoria Largest city Vancouver Official languages English Government - Lieutenant-Governor Steven Point - Premier Gordon Campbell (BC Liberal) Federal representation in Canadian Parliament - House seats 36 - Senate seats 6 Confederation July 20, 1871 (6th province) Area  Ranked 5th - Total 944,735 km... Location of Stanley Park within Vancouver. ... 1894 (MDCCCXCIV) was a common year starting on Monday (see link for calendar). ... Categories: Stub ... Brockton Point is located in Vancouver harbor at the east end of Stanley Park. ... The Noon Gun has been a historic symbol of time-keeping in Cape Town, South Africa since 1806. ... Nickname: Motto: Spes Bona (Latin for Good Hope) Location of the City of Cape Town in Western Cape Province Coordinates: , Country Province Municipality City of Cape Town Metropolitan Municipality Founded 1652 Government [1]  - Type City council  - Mayor Helen Zille  - City manager Achmat Ebrahim Area  - City 2,499 km²  (964. ... For other uses, see Liverpool (disambiguation). ... For other uses, see England (disambiguation). ... The castle dominates the Edinburgh skyline as seen here from Princes Street Gardens Edinburgh Castle is an ancient fortress which, from its position atop Castle Rock, dominates the sky-line of the city of Edinburgh, and is Scotlands second most visited tourist attraction, after the Kelvingrove Art Gallery and... For other uses, see Edinburgh (disambiguation). ... This article is about the country. ... Perth Observatory 61 cm telescope dome at Bickley. ... Location of Santiago commune in Greater Santiago Coordinates: , Region Province Foundation February 12, 1541 Government  - Mayor Raúl Alcaíno Lihn Area 1  - City 22. ...


The ceremony of "dropping the ball" at New Year's Eve in Times Square in New York City is a vestige of a visual indication of time. The first such time ball was installed in 1833 on the roof of the Royal Observatory in Greenwich, England. The ball was set to drop at 1 P.M. to enable the astronomers to establish the correct moment it should drop by observing the sun at noon. Liverpool, Edinburgh, and Perth also had balls that were dropped concurrently with the firing of the time cannons. Because the speed of light is much faster than the speed of sound, visible signals enabled greater precision than audible ones; however, the audible signals could operate under conditions of reduced visibility. In 1861 and 1862, the Post Office Directory had time gun maps published that related the number of seconds it took for the report of the time gun to reach various locations in Edinburgh. For other articles with similar names, see New Year (disambiguation). ... For other uses, see Times Square (disambiguation). ... New York, New York and NYC redirect here. ... The timeball at Greenwich is shown in the top right of picture A time ball is a large metal or painted wooden ball, visible to shipping, that drops at a predetermined time to enable sailors to set their chronometers. ... 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. ... This article is about Greenwich in England. ... For other uses, see Astronomy (disambiguation). ... The speed of light in vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness.[1] It is the speed of all electromagnetic radiation, including visible light, in a vacuum. ... This page is about the physical speed of sound waves in a medium. ... For other uses, see Map (disambiguation). ...


In many non-seafaring communities, loud factory whistles served as public time signals before radio made them obsolete. This article or section does not cite any references or sources. ... A whistle is a one-note woodwind instrument which produces sound from a stream of forced air. ...


Electrical time signals

Sandford Fleming proposed a single 24-hour clock for the entire world. At a meeting of the Royal Canadian Institute on February 8, 1879 he linked it to the anti-meridian of Greenwich (now 180°). He suggested that standard time zones could be used locally, but they were subordinate to his single world time. Sir Sandford Fleming Sir Sandford Fleming (January 7, 1827 – July 22, 1915) was a prolific Canadian engineer and inventor, known for the introduction of Universal Standard Time, Canadas first postage stamp, a huge body of surveying and map making, engineering much of the Intercolonial Railway and the Canadian Pacific... is the 39th day of the year in the Gregorian calendar. ... Year 1879 (MDCCCLXXIX) was a common year starting on Wednesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 12-day slower Julian calendar). ... This page is about Greenwich in England. ... Timezone and TimeZone redirect here. ...


Standard time came into existence in the United States on November 18, 1883. Earlier, on October 11, 1883, the General Time Convention, forerunner to the American Railway Association, approved a plan that divided the United States into several time zones. On that November day, the United States Naval Observatory telegraphed a signal that coordinated noon at Eastern standard time with 11 a.m. Central, 10 a.m. Mountain, and 9 a.m. Pacific standard time. Standard time is the result of synchronizing clocks in different geographical locations within a time zone to the same time rather than using the local meridian as in local mean time or solar time. ... is the 322nd day of the year (323rd in leap years) in the Gregorian calendar. ... Year 1883 (MDCCCLXXXIII) was a common year starting on Monday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Saturday of the 12-day slower Julian calendar). ... is the 284th day of the year (285th in leap years) in the Gregorian calendar. ... Year 1883 (MDCCCLXXXIII) was a common year starting on Monday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Saturday of the 12-day slower Julian calendar). ... The American Railway Association (ARA) was an industry trade group representing railroads in the United States. ... Timezone and TimeZone redirect here. ... Aerial view of USNO. The United States Naval Observatory (USNO) is one of the oldest scientific agencies in the United States. ...


A March, 1905 issue of The Technical World describes the role of the United States Naval Observatory as a source of time signals:

One of the most important functions of the Naval Observatory is found in the daily distribution of the correct time to every portion of the United States. This is effected by means of telegraphic signals, which are sent out from Washington at noon daily, except Sundays. The original object of this time service was to furnish mariners in the seaboard cities with the means of regulating their chronometers; but, like many another governmental activity, its scope has gradually broadened until it has become of general usefulness. The electrical impulse which goes forth from the Observatory at noon each day, now sets or regulates automatically more than 70,000 clocks located in all parts of the United States, and also serves, in each of the larger cities of the country, to release a time-ball located on some lofty building of central location. The dropping of the time-ball — accompanied, at some points, with the simultaneous firing of a cannon — is the signal for the regulation by hand of hundreds of other clocks and watches in the vicinity.

Radio time signals

This telegraphic distribution of audible and visual time signals has been obsoleted by the use of AM, FM, shortwave radio, Internet Network Time Protocol servers as well as atomic clocks in GPS satellites. This article is about an album. ... The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. ... In information technology, a server is an application or device that performs services for connected clients as part of a client-server architecture. ... “Nuclear Clock” redirects here. ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ...


The following radio stations broadcast both audible and machine readable time code that can be used as references for radio clocks and radio-controlled watches: Timecode is also the title of a 2000 film directed by Mike Figgis which was shot in one continuous take. ... A radio clock A radio clock is a clock that is synchronized by a time code bit stream transmitted by a radio transmitter connected to a time standard such as an atomic clock. ... A watch is a timepiece or portable clock that displays the time and sometimes the day, date, month and year. ...

Loran-C time signals may also be used for radio clock synchronization, by augmenting their highly accurate frequency transmissions with external measurements of the offsets of LORAN navigation signals against time standards. WWV Transmitter Building WWV is the callsign of NISTs shortwave radio station located in Fort Collins, Colorado. ... WWVB is a special NIST time signal radio station in Fort Collins, Colorado, co-located with WWV. WWVB is the station that radio-controlled clocks throughout North America use to synchronize themselves. ... WWVH is the callsign of NISTs shortwave radio time signal station in Kekaha, on the island of Kauai in the state of Hawaii. ... CHU is the callsign of a shortwave radio station founded in 1929 in Ottawa, Ontario, Canada. ... BPC can refer to: Banco de Poupança e Crédito, an Angolan bank Battery Park City, a neighborhood in New York City Bits Per Channel Blais Proteomic Center at Dana-Farber Cancer Institute BPitch Control, a Berlin-based electro and techno record label operated by Ellen Allien British Pharmaceutical... DCF77 is a longwave time signal radio station. ... HBG Prangins is a large transmission facility near Prangins, Switzerland. ... 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. ... The Time from NPL is a radio signal broadcast from the Anthorn VLF transmitter near Anthorn, Cumbria which serves as the United Kingdoms national time reference. ... Télé Distribution Française, or TDF, is a time signal service, broadcast on shortwave radio by the French Laboratoire primaire du temps et des frequences (LPTF). ... JJY is the callsign of a longwave time signal radio station similar to WWVB. The station is located in Japan, operated by a branch of the Japanese government known as the National Institute of Information and Communications Technology. ... LORAN (LOng RAnge Navigation) is a terrestrial navigation system using low frequency radio transmitters. ...


Australia lacks an easily available source of accurate time. The VNG User's Consortium[1] is campaigning for the availability of accurate time in Australia, while developing ways around this problem. The Global Positioning System can also be used as a time reference for radio clocks, but require an accurate 1PPS output to be reliably used for time signals. A device is being developed by the VNG User's Consortium that will convert GPS signals into an accurate time signal, to replace the now-defunct VNG service. GPS redirects here. ... VNG was Australias national time signal service, and operated on 2500, 5000, 8638, 12984, and 16000 kHz. ...


Many people whose needs do not require precision to the second simply rely on radio broadcasting for time signals. The BBC famously broadcasts "pips" and the strike of Big Ben at the hour in its radio broadcasts. For other uses, see BBC (disambiguation). ... Graph of the six pips The Greenwich Time Signal (abbreviated GTS) or BBC pips is a time code heard on some BBC radio stations at the start of the hour, most notably on Radio 4 and the World Service. ... “Big Ben” redirects here. ...


In the United States, many information-based radio stations (full-service, all-news and news/talk) also broadcast time signals at the top of the hour. In New York, WOR, WCBS and WINS have distinctive top-of-the-hour tones. WINS also has a tone at 30 minutes past the hour for those setting their clocks. Vancouver radio station CKNW also broadcasts time signals, using a chime every half-hour. New York, New York and NYC redirect here. ... WOR-AM is a class A (nighttime clear channel), AM radio station located in New York, New York, USA, operating on 710kHz. ... WCBS (880 kHz. ... WINS (1010 kHz. ... For other uses, see Vancouver (disambiguation). ... CKNW is the leading talk radio station in Vancouver, British Columbia. ...


WCBS and many other CBS Radio Network affiliates air a "bong" (sounding A=440Hz) that immediately precedes each top-of-the-hour network newscast. (The same bong could be heard on CBS Television Network affiliates in the 1970s.) An automated "chirp" at one second before the hour signals a switch to the network broadcast. The CBS Radio Network provides news, sports and other programming to more than 1,000 radio stations throughout the United States. ... This article is about the broadcast network. ...


In Los Angeles, KFWB broadcasts a tone precisely on the hour and half-hour during regular news broadcasts (although not during special programming such as baseball games.) KNX also broadcasts a tone on the hour; however, this tone appears approximately 17 seconds late.


See also

The American Practical Navigator , written by Nathaniel Bowditch, is an encyclopedia of navigation, a valuable handbook on oceanography and meteorology, and contains useful tables and a maritime glossary. ... “Nuclear Clock” redirects here. ... Radio transmition diagram and electromagnetic waves For other uses see: radio (disambiguation) Radio is a technology that allows the transmission of signals by modulation of electromagnetic waves with frequencies below those of light. ... Radio Data System, or RDS, is a standard from the European Broadcasting Union for sending small amounts of digital information using conventional FM radio broadcasts. ... RDS is an abbreviation for all of the following: Radio Data System Random Dot Stereogram Respiratory distress syndrome Romanian Data Systems Royal Dublin Society Le Réseau des sports Inc. ... Graph of the six pips The Greenwich Time Signal (abbreviated GTS) or BBC pips is a time code heard on some BBC radio stations at the start of the hour, most notably on Radio 4 and the World Service. ... Low Frequency or LF refers to Radio Frequencies (RF) in the range of 30–300 kHz. ... Lf or LF may stand for: Left field(er), a defensive position in baseball LeapFrog, an educational toy company Lebanese Forces, a Lebanese political party Low frequency, a term in broadcasting The LF (logical framework) Line feed, a term used in printing Nippon Broadcasting System,[a Japanese radio station in... A marine chronometer is a timekeeper precise enough to be used as a portable time standard, used to determine longitude by means of celestial navigation. ... Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia. ... The Network Time Protocol (NTP) is a protocol for synchronizing the clocks of computer systems over packet-switched, variable-latency data networks. ... For terminal pagers, see more (Unix) or less (Unix). ... Not to be confused with Public Broadcasting Services in Malta. ... The vertical blanking interval (VBI) is an interval in a television or VDU signal that temporarily suspends transmission of the signal for the electron gun to move back up to the first line of the television screen to trace the next screen field. ... Vertical interval timecode (VITC, pronounced vitsee or sometimes vits) is a form of SMPTE timecode embedded as black-and-white bars in a pair of the normally unseen vertical interval lines in a television signal. ... Timecode is also the title of a 2000 film directed by Mike Figgis which was shot in one continuous take. ... A radio clock A radio clock is a clock that is synchronized by a time code bit stream transmitted by a radio transmitter connected to a time standard such as an atomic clock. ... A watch is a timepiece or portable clock that displays the time and sometimes the day, date, month and year. ... Smart Personal Object Technology (SPOT) is Microsofts initiative to attempt to create smart software and hardware that will personalize household electronics and everyday devices to make their uses more versatile. ... Spot can refer to: Look up spot in Wiktionary, the free dictionary. ... A speaking clock service is used for people who wish to know the correct and accurate time. ... Synchronization (or Sync) is a problem in timekeeping which requires the coordination of events to operate a system in unison. ... Time transfer describes methods for transferring reference clock synchronization from one point to another, often over long distances. ... A watch is a timepiece or portable clock that displays the time and sometimes the day, date, month and year. ...

External links

  • Insight into marine science: discusses the use of time balls in maritime cities
  • Travel Downunder mentions the time cannon at Perth
  • Durr Cannon Research Projects: mentions the time cannon at Cape Town
  • The VNG User's Consortium is working on ways to solve the problem of the lack of accurate time signals in Australia.
  • The Edinburgh time gun
  • Distribution of Time Signals by the U.S. Naval Observatory
  • Distributed Time Service, an upgrade to current time station technology

References

  • Downing, Michael, Spring Forward: The Annual Madness of Daylight Saving Time (Shoemaker and Hoard, 2005) ISBN 1-59376-053-1

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