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TELE-audiovision.com—
05-06/2015 —
TELE-audiovision International —
全球发行量最大的数字电视杂志
7. First test: modulating a DVB-C
transponder with 256-QAM at 354 MHz.
8. The transponder generated by the DTA-
2115 is clearly visible in the spectrum.
9. The field meter shows the corresponding
constellation diagram, the signal is locked
with no problem. This is nice to test a
receiver or to analyse the content, however,
the signal is unrealistically good.
10. DekTec allows to control the SNR of the
signal. Introducing a random background
noise will produce a more realistic
constellation and gives the tuner some
work.
11. The field meter can still lock onto the
signal, but now the bit error correction has
some work to do.
12. Second test: modulating a DVB-T2
transponder with 256-QAM and rotated
constellation. StreamXpress offers a
whole window with access to practically all
parameters for DVB-T2. Thankfully DekTec
included useful default settings.
13. The field meter could lock to the signal
without any problem. The result is a perfect
tilted constellation diagram.
14. This constellation diagram looks more
realistic… I activated the SNR functionality
on the StreamXpress software. Notice the
slightly lower MER.
15. DVB-T2 does not necessarily use a
rotated constellation. On the advanced
DVB-T2 settings panel you can turn this off.
16. Here we see the resulting DVB-T2
constellation diagram without rotation.
17. To test error handling, the
StreamXpress software allows to introduce
errors. This can come in very handy, when
error correction algorithms need to be
tested.
18. Another test: generating a DVB-H
transponder. I do not receive such signal in
my location, so it is good to be able to rely
on the DTA-2115 to obtain such a signal,
when DVB-H receivers have to be tested.
19. Any modulation can be generated. To
test this, I modulated a DVB-S2 8-PSK
signal at the unusual frequency of 456 MHz.
20. The field meter shows the generated
transponder on the spectrum. I don’t have
a suitable receiver to demodulate this
transponder, but this shows how R&D
departments could explore new frequency
and modulation combinations.
facturing process, special
software could be developed
that at the touch of a button
could play back one tran-
sponder stream after anoth-
er at different frequencies.
The technician would not
need to do anything special
in the StreamXpress soft-
ware and there would not
be any mistakes that would
have come from entering
wrong frequency informa-
tion. Even though we‘re not
professional programmers
here in the test lab, we were
easily able to create test
software like this in a short
amount of time. This shows
how the well-thought out
DekTec concept offers un-
limited possibilities. Thanks
to the open and documented
API, the new DTA-2115 can
also, as expected, be inte-
grated into user-defined ap-
plications.
Whether it‘s in R&D de-
partments, in service cent-
ers or at trade shows, if
you‘ve worked with a DekTec
modulator once, you‘ll never
want to do without it again.
With the DTA-2115, we‘re
talking about an unbeliev-
able product that can work
with any modulation and in
every standard frequency
band.
The card works as ex-
pected. Working with the
StreamXpress software is
logical and uncomplicated.
Naturally, complex modula-
tions such as DVB-T2 come
with an array of parameters
yet the presettings are rea-
sonable and if you need to
test a signal like this, you
would already know which
parameters would need to
be tweaked.
We love the new DTA-2115
and highly recommend its
use in stationary worksta-
tions.