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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.

Warnings to the general public by means of DCF77

In accordance with the DCF77 encoding scheme, only status information, but no time information has so far been transmitted in the first fourteen seconds of each minute. On behalf of the Federal Ministry of the Interior it has been investigated whether warnings could instead be transmitted to the general public in hazardous situations. The final report available since midyear 2004 favours such an extended use of the time signal transmitter.

The Bundesamt für Bevölkerungsschutz und Katastrophenhilfe (BBK, Federal Office for Civil Protection and Disaster Relief), within the sphere of business of the Federal Ministry of the Interior, is looking for an alternative to the siren systems, which are practically out of use since 1993, so that a new kind of “reveille” in hazardous situations could alert the population in cases of crisis or catastrophes. HKW-Elektronik GmbH was contracted to perform and evaluate a field test, during which the low-frequency transmitter DCF77 was integrated into the SatWas satellite warning system of the Federal Government and transmitted fictitious warning information in second marks 1 to 14.

In its final report, HKW showed that the alarming time and availability of the radio alarm system is uniformly good all over our country. The environment (countryside, congested urban area, inside, outside of buildings) and the distance to the transmitter influenced the radio reception probability only insignificantly. In contrast to this, it turned out that in detail the installation selected for stationary clocks and/or the way how wristwatches are worn exert a considerable influence. The number of false alarms was negligibly small.

Up to now no firm decision has been made whether DCF77 will in fact become part of the warning system for the general public in Germany. The Deutsche Institute für Normung (DIN), however, was entrusted to draft a norm specifying properties of future DCF77 alarm receivers together with the interested industry during 2007. As far as we are informed this draft has never been published.