Functional description and allocation of terminal pins Manual BG41/BG42/BG43
3-74 Rev. 99/49
3.2.10 DCF77 antenna module (MD36)
3.2.10.1 General
The Federal Institute of Physical Technology in Braunschweig operates a cesium atomic frequency
standard with an arithmetical response deviation of 1 second in 1 million years. This clock time is
coded (DCF77) and is irradiated from an LF transmitter in Mainflingen near Frankfurt.
The time signal irradiated from the transmitter in Mainflingen can be picked up by the intelligent
antenna DCF77.
The antenna possesses its own processor for transmitting the decoded time signal to a 20mA
interface. Every 20mA interface can be used as a communication module, for example, the SSM-
MD25 and the SSM-MD26 modules.
Every full hour the antenna module synchronizes with the quartz clock on the interface building
block, in order to provide the officially established time and not a manipulated one.
The antenna module is not an independant clock. It merely serves as the synchronisation of existing
real-time clocks.
By means of the standard interface and the open time telegram, it is possible to connect this module
to any other system with a 20mA interface. Due to the receiver evacuation, this module possesses a
greater signal-to-interference ratio. It is also possible to supply several suscribors in a chain
parameter matrix form.
Fig. 3-55: Combination DCF77 antenna with 20ma current loop module
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