Meinberg DOAL - Manual (Page 5)

5
Installation
A
B
C
DOAL/A
DOAL/R
Antenna
Receiver
Fig. 1: Installation Scheme
The maximum cable length of the fiber optical connection (C) is up to 2000 mtrs.
However, the maximum distance depends on the field strength of the received DCF
signal. If the signal is weak, the maximum possible cable length might be shorter. If a
maximum cable length is required, the optical link should be continuously, with no
additional and attenuating FO connectors, and with the most short coax cable connection
to the antenna (A) and to the receiver (B).
On the other hand, if the antenna input level is very high, e.g. due to a preconnected
amplifier (AV4) or because of quite nearness to the DCF77 transmitter (Frankfurt a. M.,
Germany), the Optical Antenna Link could be falling into a saturation that prevents the
receiver from synchronisation. To avoid such problems, the DOAL/A has a jumper on
board that lowers the incoming signal level by approx. 20dB before converting it into an
optical signal. To set this jumper the housing has to be opened by removing the
aluminium front panel.
In order to compensate the group delay caused by the DOAL system together with
PZF correlation receiver, 80km should be added in the "Distance to Transmitter" menu
(refer to the receivers manual).