1. PRODUCT REVIEW Fibre Optic LNB for Prime Focus Antennas
Optical LNB
First, let’s refresh our memories on how
a standard LNB (Low Noise Block Con-
verter) works: the LNB receives the sat-
with a Flange
ellite signals that have been focused to it
by the satellite dish and converts them to
a lower frequency range so that they can
Now for Really Large
be carried by a coaxial cable to the receiv-
er’s tuner. Since this converted frequency
range is limited to 950 to 2150 MHz, two
Antennas!
things must be done in order to receive the
entire satellite frequency spectrum.
First there’s the polarization of the signal.
Thomas Haring
It could be linear (horizontal or vertical) or
circular (left circular or right circular). We
will be discussing linear polarization here
The Global Invacom LNB first made its appearance in although most of it is also valid for circular
the summer of 2009. Without a doubt, it’s a product polarization.
that has the potential to revolutionize direct satellite A control voltage of 13V or 18V is car-
reception. But what exactly is an optical LNB? For all of ried through the coax cable to the LNB to
our readers who haven’t been following the development select which polarization to receive (13V
for vertical and 18V for horizontal). Sec-
of this new product, we’d like to provide you with a short ondly, there’s a 22 KHz control signal, also
overview. carried via the coax cable to, for example,
54 TELE-satellite — Global Digital TV Magazine — 04-05/2010 — www.TELE-satellite.com

2. TELE-satellite World www.TELE-satellite.com/...
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a universal LNB, that switches they are all connected to the English English www.TELE-satellite.com/TELE-satellite-1005/eng/globalinvacomlnb.pdf
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Up until now, this problem Romanian Românesc www.TELE-satellite.com/TELE-satellite-1005/rom/globalinvacomlnb.pdf
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If the LNB receives the 22 was solved by using LNBs with Swedish Svenska www.TELE-satellite.com/TELE-satellite-1005/sve/globalinvacomlnb.pdf
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KHz signal from the receiver, up to eight individual outputs;
Available online starting from 2 April 2010
the LNB switches to high band each output supplied the nec-
and sends that frequency essary polarization/band for
range to the receiver. If the each attached receiver. If binations and converts them need to do is route one fibre
LNB doesn’t see that control more than eight outputs were to different frequency ranges optic cable from the LNB to a
signal, the low band signal is needed, that’s when mul- between 1 and 5 GHz. The RF central distribution point. It
sent instead. tiswitches were used. Four signal is then converted to a is then split into multiple fibre
independent cables from an digital signal and then, using optic cables and routed to each
One thing is clear, only one LNB would be connected to a the built-in laser, finally carried floor of the apartment building.
of the four possibilities (ver- multiswitch which would then from the LNB via a fibre optic From there it is split again so
tical or horizontal low band distribute all four polarization/ cable. that each apartment on each
or vertical or horizontal high bands to as many users as floor is supplied with its own
band) can be carried over the needed. A GTU (Gateway Terminal fibre optic cable.
coaxial cable at any one time. Unit) converter box connected
Unfortunately, “as many as at the other end of the fibre From here the end user
For a single reception needed” isn’t entirely true. optic cable reconverts the dig- can not only connect just one
system with only one end user Using coax cable and distribut- ital signal into one that can be receiver, but he could, for
this is not a problem at all. But ing the signal via multiple mul- recognized by a standard sat- example, easily connect a Twin
if more than one user want to tiswitches leads to something ellite receiver. These GTUs are Tuner PVR in the living room,
receive satellite signals inde- you really can’t ignore: signal available in Twin, Quattro or another receiver in the kids
pendently at the same time attenuation. The signal attenu- Quad models. room and yet another box in
from one antenna, that’s when ation when dealing with 8 or the bedroom.
the first problems begin to sur- 10 connections is essentially While the Twin and Quattro
face. negligible but if 20, 30 or 40 versions (two versus four out- If a standard coaxial cable
connections are needed, then puts) are connected directly to distribution system were used,
If one person is watching a it becomes a real problem. a satellite receiver, the Quad then each apartment would
vertical low band TV channel, version delivers each of the need to be supplied with four
all the other users would be This is where the optical LNB four polarization/band com- cables from the multiswitch.
limited to watching a chan- comes in. A built-in stacker in binations to the Quad’s four As you can see, there is enor-
nel from the same polariza- the LNB takes the four differ- outputs and is used with an mous potential with this new
tion/band assuming of course ent polarization/band com- existing multiswitch distribu- technology. It greatly simpli-
tion system. fies and lowers the expense of
installing larger satellite recep-
This means that one fibre tion systems; there’s even
optic cable can be used to carry new possibilities for individual
the entire frequency spectrum users.
of a satellite. One single 3mm
thick fibre optic cable from the Up until now, Global Inva-
LNB is all that’s needed. Since com only offered an optical
this light beam carries the LNB model with an integrated
entire frequency spectrum of feed for offset antennas. We
a satellite, it’s possible to con- already put this model through
nect as many receivers as you a number of tests and were
need and operate them inde- very happy with the results.
pendently from each other.
But this model comes with a
Even if, for example, entire limitation: this LNB can only be
apartment buildings need to used with offset antennas and
be supplied with satellite sig- that means the size of the dish
nals, Global Invacom’s new won’t be any larger than about
LNB brings with it never before 1.8 meters. Thanks to ever
thought of possibilities. All you more powerful satellites, this
56 TELE-satellite — Global Digital TV Magazine — 04-05/2010 — www.TELE-satellite.com

3. BADR 26° East spectrum with the Invacom LNB NSS7 22° West spectrum with the Invacom LNB
BADR 26° East spectrum with a coaxial LNB NSS7 22° West spectrum with a coaxial LNB
Hispasat 30° West spectrum with the Invacom LNB ABS1 75° East spectrum with the Invacom LNB
Hispasat 30° West spectrum with a coaxial LNB ABS1 75° East spectrum with a coaxial LNB
BADR 26° East signal measurement with an NSS7 22° West signal measurement with an ABS1 75° East signal measurement with an
Invacom OptiScan and an optical flange LNB Invacom OptiScan and an optical flange LNB Invacom OptiScan and an optical flange LNB
58 TELE-satellite — Global Digital TV Magazine — 04-05/2010 — www.TELE-satellite.com

4. antenna size is typically more necessary cable. We used the position we moved the antenna it was 80 meters from the
than enough for normal sat- coax cable that was already in to nor how many receivers we antenna to our signal ana-
ellite reception, but not when place to supply power to the connected to the GTU at the lyzer).
you want to supply several LNB while we ran a fibre optic same time; reception results
hundred apartments. cable from the LNB to our test were very good and remained Compared to coax cable, it
center. Thanks to prefabri- constant across the entire fre- provides a significant improve-
In such a case reception cated cable lengths of 10, 30 quency range. ment in signal quality that
must be perfect even in the and 50 meters and the ease in when dealing with very weak
strongest rain storm and this connecting these cables, this The varying signal attenua- signals could make the differ-
is only possible when there is task was taken care of rather tion you would see in lengthy ence between reception suc-
sufficient bad weather reserve. quickly. coax cable because of the dif- cess or failure. Distances of
This means using large diam- ferent frequency ranges in use several kilometers could be
eter antennas; profession- Compared to coax cable that is a problem that doesn’t exist covered without any signifi-
als typically use prime focus isn’t all that sensitive to dirt, in fibre optic cable. You there- cant signal attenuation. Global
antennas for this purpose. fibre optic cable needs to be fore get lossless signal trans- Invacom has already tested
kept clean. The problem isn’t mission from the LNB to the this in the field. Another plus is
By the time you read this, the cable itself; the outer jacket converter box. This is a perfect the lower material costs (fibre
Global Invacom will have of the cable is metallic letting solution for smaller or larger optic cable at roughly 1.25€/m,
introduced an LNB specifically you bend and twist the cable cable TV service providers who a two-output converter box for
designed for use with prime as needed. It’s the connec- ideally want the best possible about 25-30€, a four-output
focus antennas: an LNB with tors on either end of the cable signal to reach their head end box for 60-70€ and a GTU con-
a C120 flange. We’ve been where you have to pay special stations. verter for 200€) compared to
given the opportunity to test attention to cleanliness. Global expensive multiswitches.
a sample LNB; it looks almost Invacom can supply a special The flange version naturally
identical to the offset version comes with all of the other Global Invacom has com-
cleaning cloth that can be used
except that there’s no feed advantages that the offset plemented their optical LNB
to prepare the connector ends
assembly. version has; all four signal assortment with the introduc-
before being attached to the
levels can be transported at tion of the flange LNB. This
LNB or the converter box.
The feed is permanently the same time by one cable. new technology can now be
mounted to the antenna so Because of this lack of attenu- used on antennas larger than
On the receiving end, we
that the LNB merely needs to ation, the signal can be split as 1.8 meters making the opti-
quickly connected the fibre
be attached via the eight holes many times as necessary. Each cal LNB more attractive to the
optic cable from the LNB to a
on the front side using the four and every output receives the professional market.
four-output GTU converter box
screws included in the pack- maximum signal level and can
which was used to connect to
age. A matching washer is of operate completely independ- Eventually you will see new
a signal analyzer as well as
course included. ently from all of the others. receivers on the market that
a positioner box that would
can handle the fibre optic cable
move the antenna.
Since no power can be sup- You can also run fibre optic directly without the need of a
cables for extremely long converter box. Not only would
plied to the LNB through a fibre We started testing the LNB
lengths without having to this eliminate the need of an
optic cable, the manufacturer after briefly adjusting the
worry about any signal loss. extra component, but you
included an external power position of the antenna; initial
It can be routed through any would then have nearly loss-
supply that is connected to the results were surprising. We
existing conduit or duct and less signal transmission and
LNB via an “F” connector. In were expecting the results to
thanks to its negligible signal limitless signal distribution
this way it’s possible to use be better than with a standard
loss is ideal for use over very from the LNB all the way to the
the coax cable from an exist- LNB but the differences were
long distances (in our case receiver.
ing satellite system to supply clearly recognizable.
power to the LNB without
having to run a new dedicated
Signal Measurements:
It wasn’t only that the opti-
Optical Flange LNB:
power line. cal LNB was more sensitive
Satellite Transponder Level MER
than the 0.3 dB flange LNB
BADR 26° East 11919 H 67.4 dBµV 9.6 dB
A rubber grommet for with coaxial output, there HISPASAT 30° West 12458 V 76.4 dBµV 13.1 dB
weather protection as well as was no appreciable signal loss NSS7 20° West 12735 H 72.8 dBµV 12.1 dB
a female-to-female “F” con- along the 80 meters of fibre ABS1 75° East 12640 V 68.0 dBµV 8.7 dB
nector also comes in the flange optic cable between the LNB
LNB package. and the receiver. This could Coaxial Flange LNB:
be seen on our signal analyzer Satellite Transponder Level MER
Installation with its higher signal level and BADR 26° East 11919 H 54.4 dBµV 6.5 dB
We quickly mounted the its significantly better MER. HISPASAT 30° West 12458 V 59.6 dBµV 12.7 dB
flange LNB on a three-meter NSS7 20° West 12735 H 53.3 dBµV 10.6 dB
IRTE antenna and routed the It didn’t matter what satellite ABS1 75° East 12640 V 52.0 dBµV 7.4 dB
www.TELE-satellite.com — 04-05/2010 — TELE-satellite — Global Digital TV Magazine 59