The Global Invacom System - Shop Online · 54 TELE-satellite International — The World‘s Largest Digital TV Trade Magazine — 09-10/2012 — ... thanks to fibre optics

54 55TELE-satellite International — The World‘s Largest Digital TV Trade Magazine — 09-10/2012 — www.TELE-satellite.com www.TELE-satellite.com — 09-10/2012 — TELE-satellite International — 全球发行量最大的数字电视杂志

The Global Invacom System

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TEST REPORT Fibre Optic Distribution System

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09-10/2012

www.TELE-satellite.com/12/09/globalinvacom

Global Invacom SystemFinally a system to build really large

distribution nets without having to care at all about attenuation

56 TELE-satellite International — The World‘s Largest Digital TV Trade Magazine — 09-10/2012 — www.TELE-satellite.com

The Battle Is Over and Fiber Has Won

TEST REPORT Fibre Optic Distribution System

The carrier-to-noise ratio is one of the major concerns when designing large sys-tems to distribute satellite tv signals. When you have to deal with long coaxial cables and/or many signal splitters, your signal qual-ity degrades significantly. To keep it good enough for the most peripheral users, you have to minimize the number of signal splitter be-tween the LNB and the very last receiver and keep the total cable length as short as possible. You also need to install quite a large dish

and low noise LNB to ensure high carrier-to-noise ratio at the input of the distribution system. However, this may not work well enough for re-ally large systems.

What then? Until recently, you had no choice but to in-stall additional large dishes and LNBs and build several separate distribution sys-tems. Of course, this is not a welcome solution. It adds complexity, cost and the an-tenna farm on the roof does not make (normal) people happy. But now GlobalInva-com comes to our rescue.

Thanks to their innovative solution based on fiber optic cables and optical splitters, building even very exten-sive networks becomes easy and manageable.

In order to switch from coax cable to fiber optic cable, the very first thing needed is the conversion of the electromagnetic waves coming from a satellite (or from a DTT transmitter) to modulated light that can be then distributed over fiber optic cables. TELE-satellite readers remember that we already introduced Glo-

balInvacom’s FibreMDU Uni-versal Optical LNB. We first reported about this innova-tive LNB in TELE-satellite 04-05/2008 and in a follow-up story in TELE-satellite 08-09/2009. But this time, we had the opportunity to test something else. It was the FibreIRS LNBm whole-band LNB with integrated frequency stacker.

The FibreIRS LNBm is installed in place of an or-dinary LNB but it does not output signal in the familiar 0.95 – 2.15 GHz frequency range. And it does not re-

The FibreIRS LNBm mounted on a 90cm dish

www.TELE-satellite.com/12/09/globalinvacom

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tenuated before reaching the FibreIRS ODU32.

Except for the satellite signal, the FibreIRS ODU32 accepts also a signal from DTT/DAB/FM antennas. Preferably, the latter one should come not directly from terrestrial antennas but through a DTT proces-sor of Global Invacom de-scribed in the previous issue of TELE-satellite (Pages 16-21 in TELE-satellite 06-07-08/2012). In this way, we can achieve the best possi-ble performance. FibreIRS ODU32 has two optical out-puts as well as a connector for 20V DC power supply. GlobalInvacom provides a suitable plug type power supply unit. You do not need a separate power supply unit for the LNBm. It gets

DC power via the thick coax cable from the ODU 32.

But the picture is not com-plete yet. Two optical chan-nels have to be distributed among a number of end us-ers. To do that, you can use optical splitters like Spit2-OFpro or Split4-OF – 2 way or 4 way optical splitters offered by GlobalInvacom. At the very end of such sys-tem, a device called FibreM-DU should be connected. The FibreMDU converts the optical signal back to the RF domain. It has four out-puts. So, up to four regular satellite receivers can be connected to it and each of them will be able to receive any channel from the satel-lite the dish is directed to. No matter which sub band or polarity. That’s because

everything comes down through the fiber optic ca-bles to FibreMDU.

We started our tests with measuring the optical split-ters. Spli2-OFpro specifica-tion promises not more than 4 dB attenuation of the sig-nal (from the input to any of its two outputs). We meas-ured that the actual attenu-ation was only 3.5 dB. The same story repeated for Split4-OFpro. Its actual per-formance was better than its specifications (6 dB vs. 7 dB). This is the way good manufacturers specify their products. Once they prom-ise something, they deliver it! It is not a universal rule these days unfortunately. We are happy to say that you can trust GlobalInva-com.

Then, we decided to test the whole system. First, we measured a classical system with a very good low noise LNB installed on a 90 cm offset dish to have a refer-ence for the optical system. Our reference system had about 20 meters of coax-ial cable. The problem was which satellite we should use? A very strong one in our location - like ASTRA 19.2° East or HOTBIRD 13° East or rather a weaker one like TURKSAT 42° East. We decided to make it hard for GlobalInvacom and chose TURKSAT. Some of its tran-sponders are actually below the reception threshold of most contemporary receiv-ers. Fortunately, our satel-lite analyzer – SPAROS SAT HD of SPAUN is an extreme-

Checking the optical signal at one of the fibre optic to coax converters

TELE-satellite has introduced GlobalInvacom‘s fibre optic LNB first in 2008 and then again in 2009.

quire a receiver for switch-ing between lower or higher sub-band of Ku Band and horizontal or vertical po-larization. No, it outputs two sub-bands of Ku-Band and both polarities stacked one over another in the range 0.95 – 5.45 GHz. Such RF signal is then fed to the Global Invacom RF-to-light

converter which is desig-nated as FibreIRS ODU32. Because here we deal with very high frequencies, we can not use regular coax cable to connect these two devices. Global Invacom provides a special 2 meters long thick and stiff coaxial cable. Thanks to that, even a 5.45 GHz signal is not at-

TELE-satellite Test Editor Jacek Pawlowski testing a setup with rolls of fibre optic cable imitating a large distribution system.


ly sensitive instrument - ca-pable of processing even such weak signals. We mean signals with a MER of 5.5 dB and less. It corresponds to a C/N below 8 dB. Such tran-sponders are hardly receiv-able by regular receivers.

The optical system we built had FibreIRS LNBm in-stalled on the same 90 cm dish, FibreIRS ODU32, 100 meters of fiber optic cable, Spit2-OFpro, another 100 meters of fiber optic cable, Spit4-OFpro, another 100 meters of fiber optics ca-ble and FibreMDU to which we connected the satellite signal analyzer. As you can calculate, the system had in total 300 meters of fiber op-tic cable and two splitters in series.

The results were really astonishing! The optical system was able to deliver almost all transponders we had with a classical system

except for the two weakest transponders (12577HH and 12618HH). As we said be-fore, those two transpond-ers were below the recep-tion threshold of a regular receiver anyway. So, in fact, we did not lose anything. All the remaining transponders

were significantly stronger in the optical system. MER was at par with the classi-cal system. This means that signal quality did not de-graded despite 300 meters of cable and two splitters! You can see our results on the attached graphs.

After the first round of measurements, we changed the output of Spit2-OFpro splitter and did the second run for the optical system. And finally, we changed the output of Spit4-OFpro split-ter and repeated the meas-urements. As you can see, there was practically no dif-ference in performance what proves that all outputs of the splitters produced very similar signal. (graph.1, 2)

All the GlobalInvacom components we tested were perfectly finished off and we had absolutely no problem in making the connections. Just click, click, click and

everything was connected. All optical and RF connec-tors of the devices had pro-tective covers so that no dirt could access it during transportation or the in-stallation process. Building such optical system was like playing with LEGO blocks. It was nothing but joy.

If we connected more

fiber optic cables, splitters and converters, we could deliver exactly the same signal as presented on our graphs to not fewer but 64 satellite receivers. And all this from a single dish and single FibreIRS LNBm. If we used even more splitters or Spit4-OFpros in place of Spit2-OFpros, the number of end users would be much greater. The only thing one can expect then is some-what lower output power


DATATECHNICAL

Manufacturer Global Invacom Ltd., Great Britain

Web www.gloablinvacom.com

E-mail [email protected]

Phone +44-1621-743440

Fax +44-1621-743676

FibreIRS LNBm

Function Wholeband LN with integrated frequency stacker

Input frequency range 10.7 – 12.75 GHz

Output frequency range 0.95 – 5.45 GHz

Noise figure typ. 0.7 dB

FibreIRS ODU32

Function RFtofiberopticconverter

Satellite input frequency range 0.95 – 5.45 GHz

DAB/DTT input frequency range 217-230 MHz and 470-854 MHz

No. of optical outputs 2

Power supply 20 V DC, < 0.5A incl. wholeband LNB

Spli2-OFpro & Spli4-OFpro

Function 2wayand4wayopticalsplitters

CR typ. 50%and25%respectively

Insertion loss typ. 4dBand7dBrespectively

Jacek PawlowskiTELE-satellite

Test CenterPoland

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High signal gainVery good carrier-to-noise ratioSolid design and workmanshipActual performance better than parameter specificationAll components available from the same manu-facturer

FibreIRS LNBm is larger and heavier than a classical LNB – select a dish with a robust LNB holder

Expert Opinion

but this is not a problem as the 80-90 dBµV we achieved in our test setup was a very strong signal. Normally, you have 60-70 dBµV or so.

So, we can do nothing but heartily recommend the optical system of GlobalIn-vacom for large distribution systems. You can forget

about signal attenuation or carrier to noise ratio. Using optical components, practi-cally everybody can build a large distribution system without tedious gain mar-gin calculations or interfer-ence concerns. No more problems. The battle is over thanks to fibre optics.

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The Global Invacom System - Shop Online · 54 TELE-satellite International — The World‘s Largest Digital TV Trade Magazine — 09-10/2012 — ... thanks to fibre optics