DCF77
DCF77 is a German longwave time signal and standard-frequency radio station. It started service as a standard-frequency station on 1 January 1959. In June 1973 date and time information was added. Its primary and backup transmitter are located at in Mainflingen, about 25 km south-east of Frankfurt am Main, Germany. The transmitter generates a nominal power of 50 kW, of which about 30 to 35 kW can be radiated via a T-antenna.

DCF77 is controlled by the "Physikalisch-Technische Bundesanstalt" (PTB), Germany's national physics laboratory and transmits in continuous operation (24 hours). It is operated by "Media Broadcast GmbH" (previously a subsidiary of "Deutsche Telekom AG"), on behalf of the PTB. 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. Most service interruptions are short-term disconnections of under two minutes. Longer lasting transmission service interruptions are generally caused by strong winds, freezing rain or snow-induced T-antenna movement. This manifests itself in electrical detuning of the antenna resonance circuit and hence a measurable phase modulation of the received signal. When the maladjustment is too large, the transmitter is taken out of service temporarily. In the year 2002, almost 99.95% availability, or just over 4.38 hours of downtime, was realized. The timestamp sent is either in Coordinated Universal Time (UTC)+1 or UTC+2 depending on daylight saving time.

The highly accurate 77.5 kHz (approximately wavelength) carrier signal is generated from local atomic clocks that are linked with the German master clocks at the PTB in Braunschweig. The DCF77 time signal is used for the dissemination of the German national legal time to the public.

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. 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.
Q1082861
longwave
Concept
Q187146
time signal
Concept
Q11652
frequency
Concept
Q190157
transmitter
Concept
Q895694
Mainflingen
LOC
Q1794
Frankfurt am Main
LOC
Q183
Germany
LOC
Q430039
T-antenna
Concept
Q470438
Physikalisch-Technische Bundesanstalt
LOC
Q413
physics
Concept
Q9396
Deutsche Telekom AG
ORG
Q750463
phase modulation
Concept
Q1536
Coordinated Universal Time
Concept
Q1536
UTC
Concept
Q36669
daylight saving time
Concept
Q499193
carrier signal
Concept
Q227467
atomic clock
Concept
Q2773
Braunschweig
LOC
Q7805335
German national legal time
TIME
Q904866
Radio clock
Concept
None
watch
UNK
Q312550
DCF77
MISC
Q312550
DCF77
MISC
Q312550
DCF77
MISC
Q312550
DCF77
MISC
Q312550
DCF77
MISC
1959-01-01T00:00:00Z^^http://www.w3.org/2001/XMLSchema#dateTime
1 January 1959
DATE
1973-06-01T00:00:00Z^^http://www.w3.org/2001/XMLSchema#dateTime
June 1973
DATE
2002-01-01T00:00:00Z^^http://www.w3.org/2001/XMLSchema#dateTime
2002
DATE
1980-01-01T00:00:00Z^^http://www.w3.org/2001/XMLSchema#dateTime
1980
DATE
+77^^http://www.w3.org/2001/XMLSchema#decimal
77
NUMBER
+25^^http://www.w3.org/2001/XMLSchema#decimal
25
NUMBER
+50^^http://www.w3.org/2001/XMLSchema#decimal
50
NUMBER
+30^^http://www.w3.org/2001/XMLSchema#decimal
30
NUMBER
+35^^http://www.w3.org/2001/XMLSchema#decimal
35
NUMBER
+77^^http://www.w3.org/2001/XMLSchema#decimal
77
NUMBER
+24^^http://www.w3.org/2001/XMLSchema#decimal
24
NUMBER
+99.7^^http://www.w3.org/2001/XMLSchema#decimal
99.7
NUMBER
+26.28^^http://www.w3.org/2001/XMLSchema#decimal
26.28
NUMBER
+99.95^^http://www.w3.org/2001/XMLSchema#decimal
99.95
NUMBER
+4.38^^http://www.w3.org/2001/XMLSchema#decimal
4.38
NUMBER
++1^^http://www.w3.org/2001/XMLSchema#decimal
+1
NUMBER
++2^^http://www.w3.org/2001/XMLSchema#decimal
+2
NUMBER
+77.5^^http://www.w3.org/2001/XMLSchema#decimal
77.5
NUMBER
+77^^http://www.w3.org/2001/XMLSchema#decimal
77
NUMBER
+77^^http://www.w3.org/2001/XMLSchema#decimal
77
NUMBER
+77^^http://www.w3.org/2001/XMLSchema#decimal
77
NUMBER
instance of
instance of
location
country
frequency
country
country