Traditionally watches rely on their own movement to record the time, unfortunately unless the movement is extremely accurate, these watches can loose the accurate time. A range of modern watches are now controlled by an external radio wave or other signal. The original radio controlled watches were expensive and would often have problems obtaining a signal. Recently as the technology powering the radio controlled watches has become more refined the price has fallen significantly, allowing an entry level radio controlled watch to be purchased for under £1000.
In order to keep accurate time, these watches obtain accurate time from an atomic clock, which is then transmitted by radio waves or orbiting satellite usually each day. This means that a radio controlled watch is almost comparable with the accuracy of the atomic time source it receives it signal from, as long as the signal is available to update the current time. Atomic clocks are estimated to be accurate to 1 second in 3 million years and therefore for any practical use; these watches can keep almost perfect time.
Worldwide, these watches can receive time updates from many long range transmitters. In Europe one of the most common sources is the German DCF77 signal from Frankfurt. The radio transmitter sends the current date, time, daylight saving information, leap year notifications, and parity bits (to confirm the signal is accurate) to the countries of central Europe. The signal of DCF77 does reach the United Kingdom and is commonly used but the UK also has its own transmitter, which has recently been moved to a new location in Cumbria, from its previous location in Rugby. This transmitter uses the 60 kHz frequency while the DCF77 uses the 77.5 kHz frequency to transmit the signal.
Junghans Watches are renowned for their radio controlled collection. They offer a complete range of radio controlled quartz watches and are available to purchase on the internet. These watches draw their signal from the German transmitter. They are adjustable to for different time zones and can reflect the change between GMT and BST without manual adjustment. Prices for the range start from approximately £200 in the UK.
When purchasing a radio controlled time piece, check that the signal the watch accepts reaches your location before purchase. Usually watches purchased in one continent do not always operate in another as the standard for the frequency may vary. Check with the retailer or manufacturer as it varies from case to case.
A watch which can not obtain a signal can usually be manually set, and therefore relies on a movement (usually quartz) to record the time. For shorter periods of time the watch will keep accurate time, but if the watch does not receive a signal for an extended period of time the watch will slowly loose accuracy depending on the type of movement used. Reasons for loss of signal can often be attributed to the environment the watch is in. Steel framed buildings often interfere with the signal. It is recommended that the signal is received at least once weekly; daily updates are preferred for the most accurate requirements.
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