To Demodulate A Qam Or Dvb Qam Signal - Agilent Technologies 89410A Operator's Manual

Using Video Demodulation
(Opt. AYH)

To demodulate a QAM or DVB QAM signal

This task shows you how to demodulate the 32 DVB QAM signal generated
in ''To prepare a QAM or DVB QAM measurement''. Prior to demodulating
a video signal you must select the correct center frequency, frequency
span, and range as shown in that task. You use the same procedure to
demodulate both QAM and DVB QAM signals.
1.
Prepare the analyzer for a DVB QAM measurement as shown in the previous
task.
2.
Demodulate the signal:
Press [ ], [
Instrument Mode
3.
Select the correct demodulation parameters for the 32 DVB QAM signal (if you
are not using the signal provided on the Signals Disk, enter the parameters for
your signal) :
Press [
Instrument Mode
Press
[demodulation setup
Press [ ], [
demod format
Press [ ], 1, [
symbol rate
Press [ ], 400, [
result length
Press [ ], [
ref filter raised cosine
Press [ ], [
Return meas filter
Press [ ], .15
alpha/BT
Press [ ], [
Time
points/symbol
P ress [ ], [
pulse search off
4.
View the created signal versus the reference:
Press [ ], [
Display 2 grids
Press [ ], [
A Measurement Data
Press [ ], [
B Measurement Data
Press [ ], [ ] to activate both traces.
Shift A
Press [ ], [
Data Format
Press [
more format setup
must press this key to force both traces to display symbols as dots).
5.
Scale both traces:
Press [ ]
Auto Scale
If you are familiar using digital demodulation, you may have noticed that
setting up a video demodulation measurement and a digital demodulation
measurement is identical for QAM and DVB QAM measurements (you can
demodulate 16 QAM and 32 QAM signals with digital demodulation or
video demodulation).
9 - 10
], [
demod type Video Demodulation
], [ ], [
demod type Video Demodulation
].
], [ ].
DVB QAM 32
Return
]
MHz
]
sym
]
], [ ].
root raised cosine
], 5.
sync search off
].
],
], [ ]
IQ measured time
], [ ]
IQ reference time
].
polar (IQ) vector
], [ ] (if [
symbol dots symbol dots
], [
Return].
], [
.
Return]
] is already selected, you still