TELE-audiovision - Weltweit größte Digital TV Fachzeitschrift - page 32

TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine
— 03-04/2014
glance: Frequency, CBER, Signal Power,
C/N Ratio and MER. Notice that CBER is
shown twice: once along with the other
measurements and then a second time in
a bigger format. On the bottom you get the
list of services contained in the current
27. Pressing the MENU button will show
further options. You can edit the reception
parameters, visualize BER with more
detail, and display the MPEG picture, the
constellation diagram or a statistic with
how many uncorrected packets are being
28. This screen allows to edit the reception
parameters. Notice that the deviation
of the Symbol Rate is automatically
calculated and shown. All of these
values can be set to automatic and in
most situations the R&S EFL210 will be
able to automatically tune to the QAM
29. Here we see the demodulated MPEG
picture. The R&S EFL210 supports both
MPEG-2 and MPEG-4, so you are always
prepared for whatever standard is being
used. The OSD shows the CBER along
with the relevant channel PID’s and MPEG
30. The constellation diagram is fast and
31. With QAM64 you get four quadrants
and you can zoom into each one of the
32. This will allow analyzing the
constellation in more detail. If you give
the meter a few seconds it will display
MER and CBER as well, thus allowing a
complete analysis of the signal. Note that
CBER is the Bit Error Rate before the error
correction algorithm is applied. While
the BER after the correction is useful to
effectively see what amount of errors the
demodulator will have to deal with it is
the CBER that you want to evaluate to get
an idea on how stable the reception will
be. Many problems in the constellation
diagram can only be understood and
resolved by simultaneously considering
the constellation diagram, MER
(modulation error ratio) and CBER. Hence
it is a great feature of the R&S EFL210 to
provide all three measurements in one
screen. This is by no means common in
CATV analyzers.
33. Better than a Bit Error Rate after the
error correction: the R&S EFL210 gives a
complete statistic on uncorrected packets!
These are shown in number and time
interval, i.e. how much time passed since
the last uncorrected packet appeared.
Each uncorrected packet will produce
a glitch in the TV image, so it is nice to
have this measurement running over a
small period of time to understand if the
reception is indeed acceptable or not. It
can be used to spot intermittent problems,
34. I especially like this measurement
screen: one can see the demodulated
picture, the PID’s and MPEG info’s
together with CBER. This is a quick and
simple way to confirm if everything is
OK. Notice that the rather borderline
measurements of my CATV service is due
to the fact that I am using a very poor
signal on purpose to see how the tuner of
the R&S EFL210 handles weak signals. You
can see the results: no problem for the
R&S EFL210
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