Seite 234 - TELE-satellite-1201

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TELE-satellite International — The World‘s Largest Digital TV Trade Magazine
— 12-01/2012
Satellite meters and satellite finders
are used to professionally align satellite
antennas and to identify flaws in an ex-
isting setup. True satellite enthusiasts,
however, also have additional purposes
for meters: Satellite DXers are per-
manently on the hunt for weak or rare
signals, while feed hunters are on the
lookout for undocumented transmis-
sions (feeds).
Both target groups prefer satellite
meters with spectrum analyzers, be-
cause with the help of a satellite spec-
trum it becomes possible to spot a sat-
ellite long before a satellite receiver is
capable of locking a signal. In addition,
a spectrum display helps to identify and
analyze transponders. It is even possi-
ble to find out whether new transpond-
ers have become active at short notice,
which in many cases hints at new feeds.
Real-time spectrums are the display of
choice for those satellite enthusiasts,
as they have a refresh rate of way less
than one second.
Hence it’s no surprise that in recent
months a number of new satellite me-
ters with spectrum analyzer have been
launched. These analyzers are de-
signed to display the current signal sit-
uation – but what do you do if you need
to monitor a specific signal for a certain
length of time? This may be necessary
when you rotate a motorised antenna,
for manually aligning an antenna or for
performing a long-term measurement.
In ham radio circles a so-called wa-
terfall diagram is used for exactly those
purposes: It shows the spectrum over a
period of time using the three parame-
ters of frequency, signal level and time.
This would actually require a three-di-
mensional diagram, something that can
only be achieved with great effort. In
order to display all required information
without having to do 3D calculations,
one parameter (signal level in our case)
is colour-coded.
So in a waterfall diagram the x-ax-
is refers to frequency and the y-axis
shows time as well as – in a gradual col-
our scheme – signal level. A waterfall
diagram is drawn up line by line from
top to bottom, with each line describing
a full spectrum. Actually, this is how the
name was derived: Like in a waterfall,
information flows from top to bottom.
We wanted to provide proof that a
waterfall diagram can actually work for
satellite meters as well and to that end
we used three different 8dtek satel-
lite meters: Xtra-S, Gifted and Desired
(please refer to TELE-satellite issues
06-07/2011 and 08-09/2011 for test
reports about these devices). They are
absolute exceptions in their price seg-
ment as all of them offer a functional
spectrum analyzer.
It’s rather striking to discover that the
manufacturer decided to focus on ei-
ther speed or display resolution: While
the 8dtek Xtra-S boasts a real-time
spectrum display – albeit at low resolu-
tion – the Gifted and Desired models
impress with high-resolution displays at
the cost of display build-up time.
All three models feature a video out-
Unconventional thinking
turns 8dtek satellite
meters into genuinely
professional tools – without
costing a penny!
Vitor Martins Augusto
Image 1: The three satellite meters Desired, Xtra-S and Gifted from
manufacturer 8dtek were at our disposal for experimenting.
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