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TELE-audiovision International — The World‘s Leading Digital TV Industry Publication

— 03-04/2015

signal containg all the tran-

sponders from the original

satellite Ku Band. What can

we do with that?

Those of our readers who

still remember our previous

test reports of GlobalInva-

com products may remem-

ber another of GlobalInva-

com’s products: a dedicated

device converting the whole-

band electrical signal to the

optical domain: the GI Fi-

breIRS ODU. Normally, you

would use the GI FibreIRS

ODU along with the above

mentioned LNBm. But if you

want to multiply your distri-

bution system you connect

the GI FibreIRS ODU to the

wholeband output of the GI

FibreIRS O2E. For this pur-

pose, you need a special

short and thick coax cable

because of the high band-

width. At the output of the

GI FibreIRS ODU we get the

optical signal again but much

stronger than at the input of

the GI FibreIRS O2E. We may

say that a combination of the

O2E and the ODU forms a

kind of an optical amplifier.

However, it is not an ordi-

nary amplifier. An ordinary

amplifier would amplify op-

tical signals but could not

maintain the signal quality as

good as in the input. In other

words, we would get a strong

enough signal to be split

again but its carrier-to-noise

or MER would be worse. Not

so here! The combination of

the GI FibreIRS O2E with the

GI FibreIRS ODU does not

just amplify the signal but

regenerates it. It means that

digital errors are corrected

during demodulation and

re-modulation of the signal.

Now, if we connect another

1:32 splitter after combining

the GI FibreIRS O2E with the

GI FibreIRS ODU we can ex-

pect a strong and error free

output signal as in the origi-

nal installation before that


So far about the theory.

But does it really work like

that in real life? That’s our

job to find out in the TELE-

audiovision test center! So

we collected all necessary

products: we took an opti-

cal LNB (GI FibreMDU), GI

FibreIRS Split32pro, GI Fi-

breIRS O2E, GI FibreIRS

ODU, GI FibreIRS Split16pro

and GI FibreIRS Quad GTU

converter. We connected all

these devices as shown in

the measurement setup cir-

cuit diagram (Fig. 1).

Figure 1 also presents our

optical signal measurement

results. As you can see, the

strong signal at the output

of the optical LNB is attenu-

ated by 16.65 dB when pass-

ing through the 1:32 splitter,

then it is boosted by 16.4

dB after passing the O2E

and ODU combination. So,

in fact, its original strength

is almost exactly recreated

at the output of the ODU.

We decided to split the sig-

nal again, this time by a 1:16

splitter and convert it to the

form acceptable for a regu-

lar satellite receiver in the

Quad GTU converter. Would

we have used another 1:32

splitter we would have got-

ten almost exactly the level

of -8.9 dBm which was pre-

sent at the input of the O2E

and ODU combination. So we

may say that combining the

GI FibreIRS O2E and the GI

FibreIRS ODU plus a GI Fi-

breIRS Split32pro will result

Fig. 1 Test setup circuit diagram.