Rohde & Schwarz R&S FSL3 - Modulation Errors Measurement (Modulation Analysis)

Cable TV Measurements (Option K20) R&S FSL
1300.2519.12 2.76 E-11
6. To display the constellation diagram unchanged, while the I/Q samples are collected in the
background, press the Freeze softkey. To switch back to the continual update of the display, press
the Freeze softkey again.
7. To adjust the input attenuator, press the Adjust Attenuation softkey.
8. Press the RUN key.
Fig. 2-54 Digital TV constellation measurement
Modulation Errors measurement (modulation analysis)
This measurement determines the modulation accuracy. The measurement results are checked against
the limits and displayed in a table. In this table, only the less important result parameters of digital TV
signals are displayed (for details see Table 2–8). The important result parameters are provided by the
Overview measurement.
Result parameters that failed the check are displayed in red and bold characters, the table cell is
marked with a star. Result parameters that passed the checks are displayed in green characters. A
global pass or fail comment is displayed in the upper left table corner on a green (for passed) or red (for
failed) background.
Table 2–8: Result parameters – Modulation Errors
Parameter Description Definition
Amplitude
Imbalance
Measure for unequal amplitude
gains of in–phase and quadrature
singal paths of the transmitter's IQ
mixer. An ideal IQ mixer results in
0 %.
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%1001,min,max 





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vvvv
QIQI
v
I
: amplification of in–phase signal path
v
Q
: amplification of quadrature signal path
Quadrature Error Phase offset relative to the ideal
phase difference (i.e. 90 deg)
between the in–phase and
quadrature signal paths. An ideal
IQ mixer results in 0 deg.
Carrier Suppression Suppression of carrier; perfect
suppression results in –\ dB.