This is an experimental service, aimed to one day replace the German network of civil defence sirens.Ĭivil protection and weather forecast signal
#GE DIGITAL CLOCK RADIO CODE#
Since 2003, fourteen previously unused bits of the time code have been used for civil defence emergency signals.
Central European Time (CET) / Central European Summer Time (CEST) bit.Imminent change of CET to CEST, or vice versa, Announcement bit.The transmitted data signal is repeated every minute. The same data signal is also phase modulated onto the carrier using a 512 bit long pseudorandom sequence ( direct-sequence spread spectrum modulation). The DCF77 station signal carries an amplitude-modulated, pulse-width coded 1 bit/s data signal. The low-frequency T-aerial antennas of the continuously operated DCF77 signal in Mainflingen at night Time signal
#GE DIGITAL CLOCK RADIO TV#
Further industrial time-keeping systems at railway stations, in the field of telecommunication and information technology, and at radio and TV stations are radio-controlled by DCF77 as well as tariff change-over clocks of energy supply companies and clocks in traffic-light facilities. The accuracy of the DCF77 amplitude-modulated time signals suffices for the every-day use of clocks and watches by consumers where primarily the long-term accuracy matters. The DCF77 longwave radio emission offers penetration into buildings and the time-transmissions can be received by small ferrite antennas incorporated in the case of radio-controlled low-cost time keepers without the help of exterior antennas. Radio clocks and watches have been very popular in Europe since the late 1980s and, in mainland Europe, most of them use the DCF77 signal to set their time automatically. The DCF77 time signal is used for the dissemination of the German national legal time to the public. The highly accurate 77.5 kHz ( 3 868.289 7806 m wavelength) carrier signal is generated from local atomic clocks that are linked with the German master clocks at the PTB in Braunschweig.
The timestamp sent is either in Coordinated Universal Time (UTC)+1 or UTC+2 depending on daylight saving time. In the year 2002, almost 99.95% availability, or just over 4.38 hours of downtime, was realized. When the maladjustment is too large, the transmitter is taken out of service temporarily. This manifests itself in electrical detuning of the antenna resonance circuit and hence a measurable phase modulation of the received signal. Longer lasting transmission service interruptions are generally caused by strong winds, freezing rain or snow-induced T-antenna movement. Most service interruptions are short-term disconnections of under two minutes. With Media Broadcast GmbH, a temporal transmission availability of at least 99.7% per year or under 26.28 hours of annual downtime has been agreed upon.
It is operated by Media Broadcast GmbH (previously a subsidiary of Deutsche Telekom AG), on behalf of the PTB. The transmitter generates a nominal power of 50 kW, of which about 30 to 35 kW can be radiated via a T-antenna.ĭCF77 is controlled by the Physikalisch-Technische Bundesanstalt (PTB), Germany's national physics laboratory and transmits in continuous operation (24 hours). In June 1973 date and time information was added. It started service as a standard-frequency station on 1 January 1959. DCF77 is a German longwave time signal and standard- frequency radio station.
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