Seite 94 - TELE-satellite-1203

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TELE-satellite International — The World‘s Largest Digital TV Trade Magazine
— 02-03/2012
To demonstrate how the waterfall di-
agram changes if the antenna is shifted
to the left or the right, we deliberately
misaligned our dish. Figure 6 shows the
consequences of moving the entire mo-
tor/antenna assembly to the left. The
western satellites have vanished. The
overall reception capabilities have been
reduced. The large green background
is a result of the way the SPAUN SP-
AROS 609 behaves: even though the
level scale was fixed manually, the ana-
lyzer balances the scale anyway when
there‘s only background noise being re-
ceived. This is distorted somewhat by
our software - there should be blue or
dark gray here instead of green.
Then we turned our antenna to the
right. The waterfall diagram now shows
that only the western satellites are be-
ing received while the eastern satel-
lites can no longer be seen. If you look
closely at the diagram, you‘ll notice
that Astra 19.2E is still weak but recog-
nizable. This is because the Astra 19.2
satellite has an above average power
It‘s important to mention at this point
that the user doesn‘t have to set any-
thing up! The waterfall diagram is gen-
erated by the continuous recording of
the spectrum. The images presented
here resulted from a manual adjust-
ment of the motor within its limits.
The waterfall diagram is a perfect
tool to be used when aligning a motor-
ized satellite antenna system. The user
doesn‘t have to worry about storing any
satellite positions in their DiSEqC mo-
tor; the motor needs only to be moved
from its eastern limit to its western
limit and with the aid of the waterfall
diagram the installer can quickly inter-
pret what corrections need to be made.
Another application would be the
documentation of an installation. A
complete waterfall diagram across the
entire range of a motor would consti-
tute reliable proof of a successful in-
stallation. It can also be used as a way
to compare how a system‘s reception
capabilities might have changed over
the course of time.
Figure 6: The antenna is shifted
to the left
Figure 7: The antenna is shifted
to the right
After we misaligned our antenna for
the purposes of generating the screen-
shots that are in this test report, it was,
of course, no trouble at all to realign
our dish with the help of the waterfall
One thing is for sure: in the end our
antenna was perfectly realigned even
though we had to leave the signal an-
alyzer in the room since the webcam
construction could not be taken on to
the roof. Nevertheless, we were not
only able to move the antenna back to
its original position, but because of the
waterfall diagram we were able to ex-
tract the last bit of gain from our an-
tenna system.
We rewarded ourselves with a break
by watching BBC on 28.2E; it‘s not an
easy position to receive - spot beams
are used here…