The format of the service is somewhat similar to those in radio time signal services. Every ten seconds or so, a voice announces "At the third stroke, it will be [for example] twelve forty six and ten seconds...", with three beeps following. At the third beep, the time at that point is the time announced previously. Some countries have sponsored time announcements and include that in the message.
Prior to automatic systems, the subscriber rang an operator who would quote the time from a central clock in the exchange with a phrase such as "The time by the exchange clock is...". This was not precise and the operator could not always answer when the subscriber wanted.
In 1954, British made systems were installed in Melbourne and Sydney. The mechanical Speaking Clock used rotating glass discs where different parts of the time were recorded on the disc. A synchronous motor drove the disc with the driving source derived from a 5 MHz Quartz Oscillator via a multi stage valve divider. This was amplified to give sufficient impetus to drive the motor. Because of the low torque available, a hand wheel was used to spin the motor on start up.
The voice was provided by Gordon Gow.
The units were designed for continuous operation. Both units in Melbourne and Sydney were run in tandem (primary and backup).
For daylight saving time changes, one would be on line while the second was advanced or delayed by one hour and at the 02:00:00 Australian Eastern Standard time, would be switched over to the standby unit.
As well as the Speaking clocks, there was ancillary equipment to provide timing signals, 1 pulse per second, 8 pulses per minute and 8 pulses per hour.
The Time and Frequency Standards Section in the PMG Research Laboratories at 59 Little Collins Street, Melbourne maintained the frequency checks to ensure that the system was "on time".
From a maintenance point of view, the most important part of the mechanical clocks was to ensure that they were well oiled to minimise wear on the cams and to replace blown globes in the optical pickups from the glass disk recordings.
When Time & Frequency Standards moved from 59 Collins Street to Clayton, the control signals were duplicated and a second bank of Caesium Beam Primary standards installed so the cutover was transparent with no loss of service.
This mechanical system was replaced with a digital system in 1990.
Each Speaking Clock ensemble consisted of two announcing units (Zag 500), a supervisory unit (CCU 500), two phase locked oscillators, two pulse distribution units, a Civil Time Receiver, (plus a spare) and two or four Computime 1200 baud modems.
The voice was provided by Richard Peach.
The various components were sent for commercial production after a working prototype was built in the Telstra Research Laboratory (TRL). Assmann Australia used a German announcing unit and built a supervisory unit to TRL specifications.
Design 2000 incorporated TRL oscillators in the phase locked oscillator units designed at TRL and controlled by two tone from the Telstra Caesium beam frequency standards.
Ged Company built civil time receivers. The civil time code generators and two tone generators were designed and built within TRL.
Each state capital had a digital speaking clock for the local time of day with one access number Australia wide, 1194.
In 2002 the Telstra 1194 service was migrated to Informatel (who use their own technology - but kept the original voice of Richard Peach), whilst the other time services (e.g. hourly pips to radio stations) was retained as a service by Telstra.
In May 2006 the remaining Telstra services were withdrawn and the digital hardware was decommissioned.
The 1194 service, though no longer provided by Telstra, is still operational as at July 2008.
NRC time is referred to its primary cesium atomic clocks designed, built, and maintained at the NRC time standards laboratory in Ottawa.
The NRC provides a speaking clock service; voice announcements of Eastern Time are made every 10 seconds, followed by a tone indicating the exact time. This service is available to the general public by dialing (613) 745-1576 for English service and (613) 745-9426 for French service. Long-distance charges apply for those calling from outside the Ottawa/Gatineau area.
The English message, from an older male voice, is in the following format: "NRC, Eastern (Standard/Daylight) Time, x hours, x minutes, and x seconds." This is followed by a single beep. The word "exactly" (pronounced "exacté") replaces "and x seconds" at the top of the minute. Additionally, there is a tick every second in the background.
NRC also provides shortwave radio clock time signal broadcasts, on specific frequencies (3330 kHz, 7335 kHz and 14670 kHz) as well as on the English (CBC Radio) and French (Radio-Canada) radio networks of the Canadian Broadcasting Corporation once per day; the former at 13:00 (1:00pm) and the latter at 12:00 (noon) Eastern Time. It is also heard on TV via the Cable Public Affairs Channel (CPAC) when the Canadian Parliament is not in session.
The NRC also supports Network Time Protocol (NTP) as well as a web-based clock service.
Higher phone rates apply when dialing numbers with the code '8' in France (from within the country or from abroad)
A speaking clock in Hamburg is available by dialing
Just the normal fixed line phone rate applies.
In 1969 this system was decommissioned and replaced by a machine that looked like a record player with three pick-up arms. The speaking clock was now nation-wide available through the number 002 and was much more accurate, telling the time in 10 second intervals followed by a beep, indicating the precise moment. The text was spoken by actress Willie Brill and had the following format: "Bij de volgende toon is het .. uur, .. minuten en .. seconden" (at the following tone, it is .. hour, .. minutes and .. seconds). The service was now called over 130 million times a year.
Finally, in April 1992, the whole machinery has been replaced by a digital machine with no moving parts. The (digitized) voice has been provided by actress Joke Driessen and the clock is being kept accurate by German longwave transmitter DCF77. In accordance with international guidelines (the double-zero should be used as an international prefix), the number 002 has been replaced with 0900-8002. Though nowadays many people have digital wrist watches, mobile phones or computers telling the time accurately, the service is still being called approximately four million times a year, especially around New Year's Eve and when the daylight saving time changes.
The announcement is then followed by three beeps. At the third beep (or 'stroke') the time is that which was announced previously. Other operators run their own speaking clocks with broadly similar formats, or seem to redirect to BT's service.
Speaking clock services are not, in fact, always useful for amateur scientific purposes, since the time feed for the speaking clock is not always ensured to be exactly accurate, plus time delays through the telephone. However the BT service is assured to be accurate to five thousandths of a second.
A speaking clock service first started in Britain, from July 24 1936. It was obtained by dialling the letters TIM (846) on a dial telephone, and hence the service was often colloquially referred to as "Tim". However this code was only used in the telephone systems of the cities of London, Birmingham, Edinburgh, Glasgow, Liverpool and Manchester. Other areas initially dialled 952 but with the introduction of Subscriber Trunk Dialling it was changed to 80 and later 8081 as more 'recorded services' were introduced. It was standardised to 123 by the early 1990s.
During the Cold War, the British Telecom speaking clock network was designed to be used in case of nuclear attack to broadcast messages from Strike Command at RAF High Wycombe to HANDEL units at regional police stations. From there, automatic warning sirens could be started and alerts sent to civil defence volunteers equipped with manual warning devices. The rationale for using an existing rather than a dedicated system was that it was effectively under test at all times, rather than being activated (and possibly found to be faulty) only in the event of war. The signals to automatic sirens were sent down the wires of individual (unaware) subscribers for the same reason - a customer would report any fault as soon as it occurred, whereas a problem with a dedicated line would not be noticed until it was needed.
A version of the speaking clock was also used on recordings of the House of Parliament made by the BBC Parliament Unit, partly as a time reference and partly to prevent editing. On a stereo recording, one track was used for the sound and the other for an endless recording of the speaking clock - without the pips, as these were found to cause interference.
On the occasion of a leap second, such as at 23:59:60 on December 31 2005, there is a one second pause before the beeps, thus keeping the speaking clock in sync with Coordinated Universal Time. The current source of UK time is provided, though not monitored by the National Physical Laboratory, UK.
In much of California, a speaking clock could be reached until September 19, 2007, by calling various numbers, depending on the location of the caller. AT&T announced that it would discontinue this service in September 2007, due to outdated equipment break downs, and to free up additional phone numbers. For all area codes in Northern California, the number was 767-2676, and was often indicated by its telephone acronym, POPCORN. The speaking clock service was actually active for all numbers of the format 767-xxxx, but "POPCORN" is the most popular acronym, and is even used in common speech. Officially, the telephone number listed for the time recording was 767-8900.
In other locations, different telephone exchanges are or were used for the speaking clock service. In these areas, the numbers were usually quoted with the -xxxx, -2525 or -1212 ending. For example,
Various other numbers were used in other localities. In Wisconsin, the former Wisconsin Bell reserved the ending numbers -0123 in the dominant exchange for a city for time and temperature information.
Here is the list of active numbers as of August of 2008 (the 'xxxx' could be either -0123, -1234, -1212 or -2525):
Every ten seconds, a voice announced the time of day according to this formula: "Good (morning / afternoon / evening). At the tone, (time zone) (standard / daylight) time will be (hour):(o'clock / minute) (exactly / and (n) seconds)," followed by a one-second tone. There was a brief, albeit noticeable pause between the minutes and the seconds announcement, as the seconds portion was a separate recording. The seconds portion was always given in multiples of ten, or was omitted for the word "exactly". For example, such as message could be:
Many shortwave radio time signal services provide speaking clock services, such as WWV (voiced by John Doyle) and WWVH (voiced by Jane Barbe), operated by the National Institute of Standards and Technology from the United States of America. To avoid disruption with devices who rely on the accurate timings and placement of the service tones from the radio, the voice recording may be "notched" clear of some of the tones.
The time as provided by WWV is also available by telephone, by calling +1 303 499 7111. WWVH (an auxiliary location in Hawaii) is available at +1 808 335 4363.
The time as provided by TellMe voice portal is available by dialing toll-free 1-800-555-TELL (1-800-555-8355, say time when prompted).
Electronic speaking clocks and wristwatches are available, many marketed to the visually impaired.
Many telephone answering machines and similar devices include a speaking clock capability so they can announce the time when a message was received.
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"AT the signal, it will be 12.36 and four seconds. . . beep." The speaking clock celebrates its 40th birthday this year. But the number of people calling and waiting for the beep has fallen more than 99 per cent.
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