EFR System

Range of reception

EFR’s three transmitters, each with a range of 500 kilometres, give reliable coverage over a large part of Central Europe.

EFR’s three fixed transmitter stations are located at Mainflingen near Frankfurt am Main, at Burg near Magdeburg and close to the Hungarian capital Budapest. They transmit signals using long-wave radio frequencies that are reserved exclusively for radio ripple control throughout Europe.

Long-wave transmission guarantees very wide coverage, and gives reliable usage of EFR’s signals across a radius of about 500 kilometres. Its radio waves penetrate deep into the earth and provide good reception even in low-lying valleys or basements.

 

The central computers at the transmitter stations carry out administration tasks and pass on the telegrams to the transmitters. They ensure that each individual transmission request from any subscriber is dealt with.

The telegram transmissions are automatically repeated. In the pauses between subscriber transmissions, date and time synchronisation is carried out (currently this is performed every 10 seconds).

A wide range of safety measures guarantees the functionality of the system even under very harsh conditions. The central computer and the transmission systems are built redundantly to guarantee the highest availability.

Lightning protection, a UPS system and a diesel-generator ensure continuity of operation in the event of a mains supply outage. However if the signals from the transmitter do not appear, the receiver can retrieve individual basic programs (switching clock function) stored in the program memory.

 

The favourable properties of ground waves permit good reception of EFR’s signal even in low-lying valleys or basements.

The signals sent out from the transmitter reach the receiver via two paths:

  • as ground waves, propagated along the Earth’s surface, and
  • as space waves, reflected back from the D-layer in the ionosphere.

It is only the ground waves that are of significance for radio ripple control, since they possess the following properties:

  • ground waves can follow the curvature of the Earth’s surface
  • due to their low frequency, the electromagnetic field of long-waves penetrates deep into the earth (unlike that of high frequency mobile radio).

 

Technical Data for Transmitter Stations

Transmission power of each transmitter

100 kW

Transmission frequencies

Mainflingen

129,1 kHz

Burg

139,0 kHz

Lakihegy

135,6 kHz

Type of modulation

Frequency modulation

Frequency deviation

+/- 170 Hz

Data rate

200Bd