Products > Test Equipment
SDG6022X QAM Mod. displayed on SSA3032X-R
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markus_jlrb:
@nctnico

nice to read this - I was doubting my old knowledge.
In the case you would like to receive as LTE sig from the
tower, you need your own clock recovery which is not always
easy to achieve especially when you have propagation
distortions and overlapping due to multi path.
This was the most difficult problem to be solved during
my time in the lab decades ago.
Many genius engineers were working on this problem
to solve for QAM128 and QAM256 during my time at
the company and elsewhere. The had developed adaptive
equalizers to regenerate the clock and data stream.
Was a very interesting time for me as a young student.

Markus   
nctnico:
Nowadays you can do such things in software on a PC with an SDR. Still not easy but you can receive & track an LTE signal for sure. I've done some high level programming in this area to track the clock synchronisation of LTE towers.
tautech:

--- Quote from: markus_jlrb on September 14, 2023, 07:14:47 am ---Thanks tautech, to point me the proper device config.
As already stated by you the error rate decrease significant when syncing the clock of both devices.

--- End quote ---
I cannot know how you did these tests therefore suggested you sync instruments however there maybe something else going on.
Try referencing one and not the other.
Maybe also remove the mains earth between them and rely on the signal cabling to bond them.

But agree it shouldn't be this difficult but unfortunately I do not have an analyzer to do tests right now.  :(
Bump me for tests at the end of Sept.
gf:

--- Quote from: markus_jlrb on September 14, 2023, 05:31:35 pm ---In the case you would like to receive as LTE sig from the tower, you need your own clock recovery which is not always easy to achieve especially when you have propagation distortions and overlapping due to multi path.

--- End quote ---

That's where OFDM (with many subcarriers and a low symbol rate per subcarrier) can help.
I thought that LTE would use (a variant of) OFDM anyway, and not raw QAM :-//
markus_jlrb:
Dear responders  to my thread,

we have not to mix my intention just testing the QAM64 Modulation
generated by the SDG6022X on the SSA3032X-R as a playground I
did while testing the SSA which I get borrowed, with the mentioned
problem of measuring radio signals from a LTA tower mentioned
by nctnico, which is more sophisticated as only connection two devices
(SDG and SSA) via plain coax cable (clock synced or not).

If the SSA3kX-R could be used for this kind of wireless LTE measurement
is not clear to my due to lake of knowledge in this field especially in terms
of LTE.

I'm more keen of collection some knowledge in DVBC/DVBS transmission
and the usage of such RT SSA device for diag purpose.

Markus

 
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