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135 —
12-01/2012 —
TELE-satellite International — The World‘s Largest Digital TV Trade Magazine
quencies through the coax
cable to the receiver, and if
no 22 kHz signal is sent, the
low band frequencies arrive
at the box.
In summary, it becomes
quite obvious that a coax
cable is only able to take
care of one scenario at a
time (vertical or horizontal
low band, vertical or hori-
zontal high band). For sim-
ple reception setups with
only a single user these
restrictions do not mat-
ter at all. Things only get
messy as soon as several
receivers use a single coax
line for receiving satellite
television. What happens
if, for example, receiver 1
requests a horizontal high
band signal from the LNB,
while at the same time re-
ceiver 2 requires a vertical
low band signal? In a first-
come, first-serve scenario
receiver 2 would have to do
with the range receiver 1
has requested, if all that is
available is a single line to
the LNB. This would by an
absolute no-go in everyday
use so that other routes
have to be chosen for un-
limited reception by all us-
ers in a multi-user system.
The method of choice so
far has been to use LNBs
with up to four outputs,
each of which can offer
any band and polarisation
requested by up to four
separate receivers. If the
number of receivers hooked
up to an antenna exceeds
that number, multi-switches
need to be installed which
receive all four reception
bands/levels via separate
coax cables and then dis-
tribute the signals to any
number of receivers, with
each user having full access
to all channels. Unfortu-
nately, what we just called
‘any number of receivers’
in the previous sentence is
in actual fact a somewhat
limited affair. Signal distri-
bution with multi-switches
via coax cables is subject to
considerable signal attenu-
ation. While this generally
has only negligible effects
in smaller set-ups of up to
10 outputs, it can pose seri-
ous problems if that number
increases to 30, 40 or even
Now this is where the
optical LNB from GlobalIn-
vacom comes into play. A
stacker that is built into the
LNB distributes all four re-
ception levels (vertical low
and high bands, horizon-
tal low and high bands) on
different frequency ranges
between 1 GHz and 5 GHz.
After that, the RF signal is
converted into a digital sig-
nal which is then transmit-
ted by laser via a fibre optic
cable. On the receiving end
of the line a GTU (gateway
termination unit) converter
box receives the digital sig-
nal and re-converts it into a
conventional satellite signal
that will be accepted by all
satellite receivers.
The GTUs are available
as Quatro or Quad models,
with the Quad versions de-
signed for direct connection
of receivers, and the Quatro
model for feeding an exist-
ing multi-switch distribution
system, as it provides each
reception level through a
dedicated output.
So what’s the big deal? No
big deal at all: A single 3 mm
fibre optic cable is enough
to distribute the entire fre-
quency range of a satellite
to any number (and this
time we really mean it!) of
receivers, with no need for
a 22 kHz signal for switch-
ing between the low and
high bands. The beam of
light travelling through fibre
optic cables carries all fre-
quencies at the same time,
so that each receiver within
the distribution network is
absolutely independent in
its selection of channels.
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Even if you need to pro-
vide satellite television to
entire apartment buildings
or estates GlobalInvacom
has the perfect solution: A
single fibre optic cable is led
from the LNB to a central
distribution point where the
initial light beam is split into
several new light beams,
which are transmitted to
individual levels of a build-
ing, for example. There the
light beams are split once
more until each apartment
receives a dedicated beam.
Even within each apartment
it’s possible to hook up as
many receivers as you like,
since each beam of light
carries the satellite’s entire
frequency spectrum at any
given time.
Contrary to coax-based
distribution it is perfectly
feasible with GlobalInva-
com’s optical technology
to use a twin-tuner PVR in
the living room, a receiver
in your child’s room and a
box in the master bedroom
at the same time, without
any restriction or interfer-
ence whatsoever. Try the
same with coax cables and
you’d need four separate
lines from the multi-switch
to your apartment alone.
The potential of this new
optical distribution technol-
ogy is clear to see for eve-
ryone. Not only does it take
an awful lot of effort and
trouble off any professional
installer’s shoulder, it also
offers new possibilities to
private users. What’s more,
a fibre optic cable is capable
of transmitting much more
than the entire frequency
spectrum of a satellite. Ter-
restrial TV and radio can be
fed into the system without
much ado and if you want
do provide high-speed In-
ternet access throughout
your home or set up a net-
work connection between
various devices then you
can use the same fibre optic
cable for those purposes as
It’s no wonder then that
GlobalInvacom was able to
convince the professional
satellite world in a breeze
with its optical LNB tech-
nology, and with the newly
launched installation ac-
cessories the company will
make installation and main-
tenance even easier.