Meinberg DCF77 Manual
Meinberg DCF77 Manual

Meinberg DCF77 Manual

Receiver module
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RU226
DCF77-receiver

General information about DCF77

The Meinberg receiver module RU226 receives the signal of the long wave transmitter DCF77.
This long wave transmitter installed in Mainflingen near Frankfurt/Germany transmits the refe-
rence time of the Federal Republic of Germany. This time reference is either the Central European
Time (MEZ) or the Central European Summer Time (MESZ).
The transmitter is controlled by the atomic clock plant at the Federal Physical Technical
Institute (PTB) in Braunschweig/Germany and transmits the current time of day, date of month
and day of week in coded second pulses. The complete time information is available once every
minute.
At the beginning of every second the amplitude of the high precision 77.5kHz carrier frequency
is shifted to 25% for a period of 0.1 or 0.2 sec. The length of these time marks represents a binary
coding scheme using the long time mark for logical ones and the short one for logical zeroes. The
information about the current date and time as well as some parity and status bits can be decoded
from the time marks of the 15th to the 58th second every minute. The absence of any time mark at
the 59th second of a minute indicates the beginning of a new minute with the next time mark.
Switching to MESZ or MEZ can be done automatically. The reception of the time information
is free of charge and does not need to be registered.

General information RU226

The module RU226 is mounted in a plastic case and contains the ferrite antenna and the comlete
straight receiver. Two LEDs are included for visualization of the demodulated time marks and the
field intensity of the DCF-signal. The case is delivered with a stick pad for easy mounting (e.g. on
windows/furniture). As an output-signal, the demodulated time marks are available at a four-wire
cable.
Figure : decoding scheme
M
R
A1
Z1, Z2
A2
S
P1, P2, P3
FUNKUHREN
Start of minute (0.1 sec)
RF transmission via secondary atenna
Announcement of a change in daylight saving
Time zone identification
Announcement of a leap second
Start of time code information
Parity bits

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Summary of Contents for Meinberg DCF77

  • Page 1: General Information About Dcf77

    DCF77-receiver General information about DCF77 The Meinberg receiver module RU226 receives the signal of the long wave transmitter DCF77. This long wave transmitter installed in Mainflingen near Frankfurt/Germany transmits the refe- rence time of the Federal Republic of Germany. This time reference is either the Central European Time (MEZ) or the Central European Summer Time (MESZ).
  • Page 2 RU226 FUNKUHREN DCF77-receiver Antenna Generally, the exact mounting of the antenna is important. It has to be placed in longitudinal direction to the transmitter (Frankfurt). The antenna should be installed with a minimum distance of 30cm to all metal objects. A distance of several meters to TV- or computermonitors should be kept.
  • Page 3 RU226 FUNKUHREN DCF77-receiver Output signal For evaluating of the DCF-time-telegramm, the module delivers the demodulated time marks. The following values for the output signal are possible: Positive pulses: High-level typ.: power supply - 1 V Low-level typ.: 0,1 V Negative pulses: High-level typ.: power supply...
  • Page 4 RU226 FUNKUHREN DCF77-receiver Connection of an optocoupler The signal level of the DCF_MARK-output isn't sufficient for some applications. In that case an optocoupler may be connected externaly to achieve the required output level. The jumper of the RU226 has to be in the default position (high-active DCF_MARK pulses) for the connections shown below.

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Ru226

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