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O.1 Radio Controlled Watches

1952At the exposition 'Electricité et Radio' in Geneva, a clock is shown which receives a radio signal every second from a master clock elsewhere in the city. The master clock was controlled by radio signals from London and Paris twice a day. The entire clock came without any moving parts. The display was made out of small fluorescent and incandescent strip lights. It was manufactured by the Swiss Short Wave Society and Patek Philippe.
1954The introduction by IBM of the first American Radio controlled Clock, model 37. The clock division of IBM was sold in 1958 to the Simplex Time Recorder Company which made the same clock under the name Simplex.
1959The Zenith Radio Corporation of Chicaco and the Hamilton Watch Company of Pennsylvania introduce the first portable radio-controlled clock.
1960At the International Chronometric Congress in M/nich, Germany, the French engineer Motte shows his radio controlled quartz clock.
1977The Physikalisch Technische Bundesanstalt (PTB) starts to transmit the Central European Time from the Official German Time Standard in Braunschweig, Germany. The radio transmitter, the DCF 77, was located at Mainflingen near Frankfurt. It was a long wave transmitter with a frequency of 77.5 kHz and a range of 1500 km. Other time signals were transmitted by the WWV at Beltsville Maryland, USA, the UK Time Transmitter at Rugby, the IG2AS in Nazaki, Japan, and the transmitters in Prangins, Switzerland, and Denver, Colorado, USA.1985 The first prototype radio-controlled (RC) domestic clocks are shown at the Basle Fair: the RC-1 and RCS-1 of Junghans, both with a 732 movement and the 'Kundo Spacetimer' of Kieninger & Oberfell. Similar technology had been used for these prototypes.
1986The first radio-controlled clocks in Europe go into production.
1.The RCS-1, a quartz clock with 68 solar cells. It costed about DM 50,000. Only 50 were manufactured completely by hand. It was a beautifully high tech-design, radar-dish shaped clock.
2.The RC-1, a less expensive clock with batteries, produced as a wall and a table model.
3.The Kundo DCF 77 Spacetimer with time indication by hands and by LCD.
1990The world's first radio-controlled wrist watch, the MEGA 1 of Junghans, is presented to the public.
1991The Junghans MEGA wrist watch with hands is marketed.
1992In September, the introduction of the prototype of the 'Citizen Multizone' takes place in Basle, Switzerland.
1993The two models of the Junghans Solar 1 are marketed, the first solar powered radio controlled watch in the world.

A caesium atomic clock produces time signals which are transmitted, binary coded, by a long-wave antenna. Reception is possible up to 2000 km. The data transmission occurs from the 21st until the 59th second of every minute, 24 hours a day, starting with the minute code, then the parity or controlled code, the seconds code, then again a parity pulse and the calendar data. This signal is received by the radio receiver in the watch and synchronises the built-in quartz movement. The amazing accuracy means a time adjustment of only one second in a million years. When no signal is received the watch uses the quartz crystal as a time base without correction. In this event, the inadequacy may reach a level of one minute a year. When the radio signal is not longer interrupted, the system corrects the error.

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Copyright © by Pieter Doensen

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