![]() ![]() When bit Z1 is zero and Z2 is one, Central European Summer Time (CET) is being transmitted. While the daylight saving time indicator is enabled if daylight saving time is currently in operation.ĭata is broadcast as a series of bits in a binary coded decimal (BCD) format.īit 15, when reset, indicates use of normal transmitter, when set, indicates use of backup transmitter.īit 16 (A1), indicates the announcement of daylight saving change.īit 17 (Z1), indicates Central European Summer Time (CEST) is in operation.īit 18 (Z2), indicates standard Central European Time (CET) is in operation.īits Z1 and Z2 indicate if daylight saving time is currently in operation. The leap second indicator is enabled if a leap-second is to be imminently inserted. A number of parity bits is also contained within the transmission that can be used for error checking purposes. DCF-77 Signal EncodingĮach minute, the transmitter broadcasts the current time in hours and minutes, the current date as day, month and year, a leap second indicator and a daylight saving time indicator. At the end of each minute the pulses can be decoded into date and time information. A 100 millisecond pulse represents a binary zero, while a 200 millisecond pulse represents a binary one. Timing data is transmitted as a series of 59 pulses, one pulse each second. Accurate time and date information is continuously broadcast, repeated each minute. The transmission is broadcast as an amplitude-modulated, pulse-width encoded data signal. Additionally, network time servers utilise low-cost radio receivers to pick up accurate time from the DCF-77 signal to synchronize the internet and local networks. There are many manufacturers of clocks and watches that receive the signal to provide accurate time. The signal can be used by timing equipment to provide precise time and date information. The signal can be successfully received as far away as the United Kingdom. This range covers most of central and north-western Europe. The broadcast has a relatively high power output of 50W, which can be received up to 2000 km from Frankfurt. The main transmitter is used in general operation, however, when maintenance work is scheduled, the backup transmitter can be switched on to provided an uninterrupted signal.Ĭaesium atomic clocks maintained by the German National Physics Laboratory provide a highly accurate source of time for the transmission. There are two transmitters located at Mainflingen to provide a redundancy. The transmitters are currently operated and maintained by the German telecommunications company T-Systems, a sub-division of the German Telecoms group Deutsche Telecom. The DCF-77 transmission is one of the oldest in the world, it has been in continuous operation since 1959. The radio signal it is broadcast at 77.5 KHz, hence it’s radio call sign is known as DCF-77. The German national time and frequency transmission is broadcast from Mainflingen near Frankfurt, Germany. The article describes the following aspects of the broadcast: This article provides information on the DCF-77 radio time signal, broadcast from Mainflingen in Germany. ![]() All provide encoded time and date information that is accurate to within a few microseconds of the correct time. In Europe, the MSF and DCF-77 signals are broadcast from Cumbria in the UK and Frankfurt in Germany. In the US, the WWVB signal is transmitted from Colorado. There are a number of national time and frequency transmissions broadcast from a number of countries around the world. ![]()
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