Atomic Watch

An Atomic watch is the most accurate of all wristwatches.

Atomic time is the official U.S. government time, its what NASA uses when its counting down a shuttle launch, and its the ultimate in precision time. By calibrating with an atomic clock a watch will have an accuracy of approximately 1 second in 100,000 years.


1990. The first atomic watch was released by the German company Junghans and was called the “Mega 1”. It had the receiver mounted in its strap and during the early morning hours would receive signals from the atomic clock in Frankfurt.


1993. Citizen followed in introducing the first analog watch capable of receiving signals from multiple atomic clocks, in Germany, Britain and Japan.

However a model designed for the mainstream market was not released until 2002.


2000. Casio, no stranger to housing radio antennas in its watches having released the first GPS watch in 1999, released their first watch capable of atomic synchronisation , the GW-100 Waveceptor watch.

In 2002 they followed that with their first solar atomic watch the G-Shock model called “The G”.


2003. Citizen added full high quality metal cases, previous models required bulky bodies in order to house the antenna and had glass backs to ensure good reception, according to Citizen these prior models had their designs compromised because of this.

2004. Seiko, a relative latecomer, launched its first range of atomic watches. The same year saw Citizen announce the world’s thinnest atomic watch at just 6.8mm thick . Thickness had been a problem in design due to the built-in antenna.
Citizen, Casio and Seiko had been competing in the development of thinner more fashionable models.

Seiko was having the internal mechanism of its atomic watches supplied by Junghans but decided to work jointly with Epson in order to try and develop thinner models.
Together they developed an internal mechanism that was 4-5mm slimmer than previous ones.
As a result Seiko then released three new models for its Dolce series which were 7.9mm thick and retailed as 73,500yen.

2005 saw Citizen introduce their CAL.H330 movement. It was the smallest atomic watch movement in the world and was developed for the purpose of use in Ladies atomic watches.


2005, Casio announced its Oceanus watches the first Atomic Solar Powered Chronographs. The Casio Oceanus range is also known for its ‘Multi-Band 5’ Atomic Timekeeping, which guarantees precise and reliable timekeeping by receiving radio time calibration signals from US, UK, Germany and two in Japan. Read more here.

How they work

From the early days of radio communication it was recognized that radio signals were a great method for conveying precise time. In 1905 the US Navy began transmitting time signals at Noon from Washington D.C and in 1910 France followed suit broadcasting signals from the Eiffel Tower at midnight. So it made sense to transmit time signals from Atomic Clocks once the technology became available.


An Atomic Clock

How does the watch synchronize with the atomic clock? The small radio antenna inside the watch decodes the time coded signals and using these signals the watch then sychronises itself. This is set to occur automatically each day. Therefore the watch never needs to be reset and has the capability to adjust automatically for daylight savings, leap years as well as even different time zones.

Atomic watches have a signal indicator which lets you know not only the signal strength but also whether synchronisation was successful. Its a good idea to check this indicator in the mornings because atomic watches are pre-programmed to receive signals during the night. This is because the antenna is small and there is less intereference at night.

reception Atomic Watch

The table below shows the time calibration signal that the watch recieves when a particular code is selected as your home city.

Signal reception is possible in the time zones represented by HKG(Hong Kong), HNL(Honolulu), and ANC(Anchorage) when reception conditions are good.

reception table Atomic Watch

Certain conditions can make reception impossible even when the watch is within one of the receptions ranges shown. Signals become weaker outside the smaller circles indicated by dashed lines in the the nearby maps, so the reception environment has a greater effect on signal reception.

The following can also affect signal reception: geographic contours, weather, climate, time of day(afternoon, evening), noise.

To improve the ability to receive signals its a good idea to place it on a window sill, with the 12 o’clock side facing towards the window. Also if possible avoid having metal objects within close proximity.

If you happen to leave the signal range the indicator will go blank, in this situation the watch will use its internal quartz mechanism to keep time until you are back within the signals range again. If you want to force your watch to search for a signal and synchronise instead of wating until its pre-programmed time, most atomic watches come with a manual receive function that can be activated.

If you want to double check (in US) you can always visit and you will see your watch matching official time down to the second.

An Atomic watch uses a quartz movement though its display may be digital or analog and is either solar or battery powered. Some watch manufacturers also refer to them as ‘radio controlled watches’.

further reading:

Casio Atomic Watches

Solar Atomic Watches