What is a radio controlled watch?

A radio-controlled watch contains a small antenna that picks up radio signals from a time transmitter linked to a high-precision atomic clock. This makes this type of watch extremely accurate, with only 1 second deviation in 100,000 years!

Why a radio-controlled watch?

With a radio-controlled watch you have one of the most secure timepieces in existence. Because the watch synchronizes every night with the nearest atomic clock, you always have the correct time and calendar available. Never adjust the time again when summer or winter time starts, or the date for a leap year.

In addition, these watches usually look very nice, with advanced chronographs, functions for pilots or outdoor sportsmen.

Some radio-controlled watches also contain a GPS function, which also allows exact location determination via satellite.

What is a radio controlled watch?
▴ Citizen Radio Controlled Pilot Watch
Image of Bering radio-controlled design watch
▴ Bering radio-controlled design watch

How does a radio-controlled watch work?

Time, date, daylight saving time and year on a radio controlled watch are received from the air via low frequency radio signals, based on which the watch automatically sets or adjusts. This is usually done at night to ensure that the watch does not interfere with other household appliances that use radio waves.

The watch picks up the signal from the nearest transmitter, within approximately 500-1500 kilometers. For the Netherlands this is the radio station DCF77 in Mainflingen, Germany.

Image Time signal transmitter in Mainflingen
▴ Time transmitter in Mainflingen, Germany. 

There are five other channels in the world: in Great Britain, the US, China and two in Japan.

Not all radio-controlled watches can connect to all transmitters. So, when you want to buy a radio-controlled watch, pay attention to which part of the world you will use the watch in. If the connection with the transmitter is lost, the watch will of course not stop immediately. It then continues as a ‘regular’ quartz watch and synchronizes when the correct transmitter is within range again.

Multi-band 6 radio-controlled watches can tune to all six available stations.

Image of Casio Waveceptor watch
▴ Casio Waveceptor watch
Image Junghans Meister Mega watch
▴ Junghans Meister Mega watch

Why is the atomic clock so accurate?

In 1967, the International System of Units established the exact duration of a second as the time between two transitions in energy levels of the Cesium-133 atom. Because this atom is very stable, the measurement of time is always the same. Time measurement according to this definition is therefore also referred to as the Cesium standard.

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