La Crosse Technology Wireless Weather Station Instruction Manual - page 10
DCF-77 RADIO CONTROLLED TIME
The time base for the radio-controlled time is a Cesium Atomic Clock operated by the Physikalisch
Technische Bundesanstalt Braunschweig which has a time deviation of less than one second in one million
years. The time is coded and transmitted from Mainflingen near Frankfurt via frequency signal DCF-77
(77.5 kHz) and has a transmitting range of approximately 1,500 km. Your radio-controlled Weather Station
receives this signal and converts it to show the precise time in summer or wintertime.
The quality of the reception depends greatly on the geographic location. In normal cases, there should be no
reception problems within a 1500km radius of Frankfurt.
Once the outdoor temperature is displayed on the Weather station, the DCF tower icon in the clock display
will start flashing in the upper left corner. This indicates that the clock has detected that there is a radio
signal present and is trying to receive it. When the time code is received, the DCF tower becomes
permanently lit and the time will be displayed.
DCF reception is done twice daily at 02:00 and 03:00 am. If the reception is not successful at 02:00 am, then
the next reception takes place the next hour and so on until 06:00am, or until the reception is successful. If
the reception is not successful at 06:00 am, then the next attempt will take place the next day at 02:00 am.
If the tower icon flashes, but does not set the time or the DCF tower does not appear at all, then please take
note of the following:
•
Recommended distance to any interfering sources like computer monitors or TV sets is a minimum of
1.5 - 2 meters.
•
Within ferro-concrete rooms (basements, superstructures), the received signal is naturally weakened.
In extreme cases, please place the unit close to a window and/ or point its front or back towards the
Frankfurt transmitter.
•
During nighttime, the atmospheric disturbances are usually less severe and reception is possible in
most cases. A single daily reception is adequate to keep the accuracy deviation below 1 second.
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