Seite 237 - TELE-satellite-1201

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237 —
12-01/2012 —
TELE-satellite International — The World‘s Largest Digital TV Trade Magazine
Image 2: This EasyCAP video grabber was
bought on eBay for approximately 5 EUR.
Image 3: The waterfall diagram shows
changes during rotation of a motorised
antenna from 30.0W to 45.0E. All satellites
between these two stop positions are
clearly indicated.
Image 4: Fine-tuning of the antenna
alignment towards HISPASAT 30.0W.
Image 5: Long-term measurement of
ASTRA 19.2E using the Desired satellite
meter. This is where the device’s high-
resolution display comes to the fore.
Image 6: Long-term monitoring of two
Image 7: Set-up with small motorised
antenna. Due to lack of DiSEqC 1.2
support of the Xtra-S it was rotated using
the button on the motor itself.
this is shown with a time element and
since it is always possible to compare
any current value with preceding val-
ues finding the perfect alignment be-
comes child’s play. In the lower image
segment you can easily see for yourself
how strong the signal is with perfect
antenna alignment.
For real-time measurement the 8dtek
Xtra-S turned out to be a perfect com-
panion. The spectrum builds up very
quickly on this meter, which is a huge
benefit. Unfortunately, however, the
display resolution is rather low, as can
be seen on images 3 and 4. 8dtek went
for higher resolutions with their Gifted
and Desired models, although at re-
duced speed. This is why those two
models cannot be used for creating wa-
terfall diagrams to document antenna
alignment and rotation. For long-term
measurement, on the other hand, they
are perfect. Such measurements are
primarily performed to find out if or
why a signal has occasional errors.
Image 6 presents the result of a
long-term measurement focusing on
two transponders on HISPASAT. No er-
rors can be seen on this measurement,
since only a period of one minute was
analysed. With our software it is of
course possible to vastly extend that
period – all you need to do is select a
time between one second and ten min-
utes instead of real-time. If you select
ten minutes, for example, every line
of the waterfall diagram corresponds
to a spectrum measurement after ten
minutes each. This allows documenting
the entire frequency range of a satellite
over a period of 24 hours. The individu-
al colours indicate any signal deviation
across the entire spectrum.
Looking at the Xtra-S, Gifted and De-
sired satellite meters by manufacturer
8dtek from many different perspectives
our respect and admiration for those
neat devices was growing all the time.
It’s hard to believe how many features
and functions can be packed into such
small meters. Battery life also never
failed to impress: Three to four hours