Digital Signal Processing Reference
In-Depth Information
grees in phase. The second coupler adds these signals again to form a sig-
nal which is now shifted by 90 degrees compared with the input signal. In
the channel separating filter, band-pass filters are connected between the
two couplers. The channel separating filter has a narrow-band input and a
wide-band input and is basically constructed in exactly the same way as a
vision/sound diplexer in analog television. The channel to be supplied
passes through the filter with 0 degrees and 90 degrees phase shift and the
signal of the other transmitters is immediately totally reflected at the filters
in the wideband input after the coupler and comes out again in aggregate
with the supplied channel at the wideband output. Both filters of the chan-
nel separating filter must be tuned at least relatively identically.
Fig. 31.11. shows a combiner with two transmitters, two mask filters,
two combiners, and patch panels at which the combiner can be bridged and
the transmitter output can be switched to a dummy load, if required, in or-
der to be able to carry out tuning and measuring work without applying the
signal to the antenna.
Trans
mitter 1
f
1
Trans
mitter 2
f
2
Aircooled/liquidcooled
dummy load
f
1
f
2
To/from further
combiners
f
1
f
2
f
1
f
2
Jumpers
Jumpers
f
1
f
2
Input
for
further
extensions
To
antenna
and
further
combiners
Fig. 31.11.
Transmitter, mask filter and antenna combiner
31.3.1.4 Antenna and Feed System
From the transmitter building on the Wendelstein mountain to the trans-
mitting antenna, a total of three lines are run which are “flexible” 50 Ohm
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