Basic HTML Version
■
43
www.TELE-satellite.com —
09-10/2012 —
TELE-satellite International —
全球发行量最大的数字电视杂志
are OK. The DS2400T offers an automat-
ic signal quality check that either shows
PASS or FAIL, depending on whether or
not the measured signal reaches a pre-
defined threshold level.
If it’s a digital signal you’re analys-
ing the display content changes and the
signal strength is shown with numeric
values and bars together with MER, PRE-
BER and POST-BER parameters. Once
again the built-in signal quality check
will indicate PASS or FAIL, thus showing
installers right away whether or not the
signal in question is all right. Using the
arrow buttons it is possible to navigate
up and down the channel list, with the
meter reacting very swiftly to new chan-
nels and displaying all corresponding sig-
nal data without significant delay. This is
what we call true value for money, and
what the DS2400T offers is much better
than just PASS, it’s closer to pass with
distinction!
Constellation
If your digital signal is error-prone and
you need to find the root cause a con-
stellation diagram can work wonders. If
it turns out that signals are not located
in the correct square field you get BIT
errors. By looking at the concentration of
dots within the cloud of dots in a constel-
lation diagram you can find out how sta-
ble your reception is. If each square field
comes with a relatively small and concise
cloud of dots there’s nothing in the way
of reliable reception. If the cloud covers a
large and more or less uncontained area
some dots may wander off into a wrong
square field and impair the overall signal
quality. Together with the constellation
diagram the DS2400T also shows signal
strength, MER, PRE-BER and POST-BER
values, thanks to the high-resolution
TFT display with its 320x200 pixels. It’s
not only brilliant to read but also allows
packing in a great deal of information
and useful details without putting at risk
usability.
BER measurement
BER measurement is used to find out
the bit error rate, or in other words: how
many faulty bits are received. There are
a number of different DVB standards
in place all around the world, and each
comes with its own distinctive auto-
matic error correction regime, which is
called VITERBI. This correction routine
makes sure that bit errors up to a certain
threshold can be corrected without gen-
erating a faulty TV image. The threshold
of bit errors lies between 10-5 und 10-
7, depending on the DVB standard used.
This means that one incorrect bit for eve-
ry 10,000 to 1,000,000 correct bits will
Thanks to a metal
strap the meter can
easily be fixed to
equipment, so that
both of your hands
are free for installa-
tion jobs.