Meinberg DCF77C51, Technical Information & Operating Instructions

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8
Installation
The radio remote clock has a built in AC power supply. After the power cable has been
connected, a green LED labeled Netz indicates that the clock is ready to operate. If the
antenna cable has been connected to both the antenna and the clock's BNC connector,
the brighness of the LED labeled Feldstärke reflects the signal strength of the 77.5
kHz carrier. In order to get the maximum signal, the antenna should be aligned in two
steps. First it should be turned slowly until the Feld LED is mostly dimmed. Finally
the antenna must be turned by 90° from this position to obtain maximum signal. The
antenna should be installed at least 30 cm away from the clock and from steel girders
or plates.
If the antenna is installed properly and the signal from DCF77 can be received
without strong distortions, the green LED labeled Modulation starts blinking exactly
once per second, corresponding to the time marks from DCF77. If this LED flashes
intermediately, there is some electrical noise around which prevents the microproces-
sor from decoding the time message. In this case, a better location for the antenna must
be found.
After reset, the red LED labeled Freilauf indicates that the clock is running on xtal
and has not synchronized with DCF77 yet. Due to the plausibility checks, it can take
up to three minutes after power-up until the clock is synchronized and this LED is
turned off. The state of this LED only changes when a new minute begins.
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