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View of the Mainflingen long-wave radio station for transmission of the DCF77 signal: transmitter building (in the back), antenna building (yellow bricks) and antenna masts.

DCF77 Receiver authorization and availability


DCF77 broadcasts in 24-h operation, a temporal availability of the DCF77 emission of annually 99.7% is guaranteed as part of the existing contractual regulation, whose duration currently is until the end of 2021. Contracting partner of PTB is Media Broadcast GmbH, in succession of T-Systems Media Broadcast, a subsidiary of the Deutsche Telekom AG.

As a replacement transmitter and a standby antenna are available, regular disconnections for maintenance work have since 1977 not been necessary. Short interruptions, however, must be expected, when change-over to the replacement transmitter and standby antenna are required due to unexpected disturbances or due to maintenance work. Since summer 1997, only short-term interruptions of the DCF77 emissions have to be expected even in the case of thunderstorms at the place of transmission; in that case, the transmitter is out of order only for a few consecutive second marks.

The above figure shows the distribution of interruptions of service with durations exceeding 2 minutes observed during the years 2015 through 2017. In 2017, the temporal availability was very high (99.92 % - not counted: disconnections of less than two minutes). The most frequent cause of long lasting service interruptions has been electrical detuning of the antenna resonance circuit due to deflections of the antenna in storms, freezing rain and snow. When the maladjustment is too large, emission is stopped.

Receiver authorzation

The legal basis in the Federal Republic of Germany for the distribution of standard-frequency receivers and radio-controlled clocks is provided by the Gesetz über Funkanlagen und Telekommunikationsendeinrichtungen (FTEG) (Act on Radio Equipment and Telecommunications Terminal Equipment). This law is the national implementation of the EU Directive 1999/5/EC (RTTE Directive). This results in rights and duties for manufacturers and distributors, importers and resellers. The basic requirements stated in Section 3 FTEG
- health protection and safety for the user and other persons,
- protective requirements concerning the electromagnetic compatibility
are to be fulfilled by the devices.

In addition to providing technical documentation in which the intended use of the device is clearly indicated (for the respective country in the EU/EEA, in its own national language), as well as the Konformitätserklärung (EU Declaration of Conformity) of the manufacturer or the distributor, the CE marking [Article 12 (1-4) Directive 1999/5/EC] of these devices is to be effected for the user. With the EU Declaration of Conformity, the manufacturer confirms that these devices fulfil the basic requirements of the Directive and the Act. If harmonising standards have been made the basis of the EU Declaration of Conformity, it can be assumed that the basic requirements have been complied with.

Class 1 radio installations (this includes DCF77 receiver equipment) can be distributed on the market without restrictions. It is not necessary to notify the regulating authorities of the individual countries regarding the distribution of these devices on the EU/EEA market.

For further information, please visit the Internet pages of the Bundesnetzagentur (Federal Network Agency) on this subject: www.bundesnetzagentur.de, "Directive 1999/5/EC".