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TELE-audiovision.com—
01-02/2015 —
TELE-audiovision International —
全球发行量最大的数字电视杂志
This quick and easy feature
truly proved its worth in our
test center, since we have of-
ten spent hours on end set-
ting up an IPTV multicast cli-
ent only to discover down the
road that the server had not
been configured correctly in
the first place. A mistake we
made more often than we
would have liked was setting
up different IPTV servers with
different ports (good), yet us-
ing the same multicast IP (not
so good). With the handy De-
viser S7000 you’d notice such
a glitch immediately.
Yet – and you might have
guessed already – the IPTV
option of the Deviser S7000
offers much more than that.
Click on any of the listed IPTV
servers to access the IPTV
measuring menu, which sum-
marises all major stream pa-
rameters. Delay times, for
instance, are always a domi-
nant issue and the S7000
provides a very useful graphic
overview. Other standard
IPTV parameters such as
MDI (media delay index), DF
(delay factor) or MLR (media
loss rate) are of course also
available at a glance. Making
use of the entire screen of-
fered by the S7000, Deviser
has found a way to present all
those different details simul-
taneously using a design that
is both practical and pleasing
to the eye.
With the TS MEAS func-
tion it’s possible to launch
the built-in transport stream
analyser for the currently se-
lected IPTV server. Inciden-
tally, this is the very same
TS analyser that also deals
with the measurement of ca-
ble, terrestrial and satellite
signals. The Deviser S7000
simply passes through the
IPTV transport stream to the
TS analyser, which is a smart
move because the latter could
not care less about the origin
of the transport stream it dis-
sects. As a matter of fact, it
might as well come from a TS
file stored on an external USB
storage medium that is con-
nected to the meter.
If you want to refresh you
memory as regards the huge
range of features and capa-
bilities of the integrated TS
analyser we suggest you have
a read of TELE-audiovision
issues 09-10/2013 and 11-
12/2013 again, which both
featured in-depth reviews of
the Deviser S7000. All those
features and functions can
just as well be used for IPTV
analysis, so you can be sure
that there is nothing left to be
desired.
With the most recent firm-
ware update Deviser strik-
ingly proves yet again that its
S7000 meter is the flagship in
TV signal measurement. With
the new IPTV option both in-
stallers and head-end techni-
cians are given important ex-
tra functions for quickly and
efficiently diagnosing errors
and malfunctions.
In addition, this new firm-
ware reminds us of all the
core benefits the Deviser
S7000 has built in right from
the start. Its modular hard-
ware and software design al-
lows the meter to be kept up
to date and ahead of the pack
throughout its service life.
The manufacturer’s code-
based approach to add ad-
ditional functions is another
tool for extended customi-
sation. You only have to get
what you really need, which in
itself is a strategy worth ap-
plauding.
Why You Need to Measure IPTV
IPTV frees the technician from worries regarding the
common problems of the distribution through a coaxi-
al cable network, like signal attenuation, distortion, etc.
However, new issues arise: because IPTV uses informa-
tion packets sharing the medium with other information
packets, timing becomes important. Problems occur if the
bandwidth is too high or if delays keep the required IPTV
packets from reaching the decoder in time.
To measure what is happening in the IPTV distribution,
several parameters can be measured. The most important
ones being:
Media Delivery Index (MDI)
– This represents the ra-
tio between the Delay Factor (DF) and the Media Loss Rate
(MLR)
Delay Factor (DF)
– This measures how big the buffer
on a virtual receiver has to be to avoid picture loss due to
the time distortions (jitter). In other words: if the packets
arrive with a delay greater than the delay factor there will
be an interruption in the picture.
Media Loss Rate (MLR)
– This indicates the number of
packets lost per second.