Rohde & Schwarz FSW13, Руководство пользователя

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Measurements
R&S
®
FSW
298 User Manual 1173.9411.02 ─ 19
advantage of an immediate final measurement is that it eliminates the risk of measure-
ment errors based on frequency drifts of the disturbance signal.
The final measurement at the marker frequency may have a different detector than
during the initial peak search. Thus, the final measurement consumes much less time
because detectors with a long measurement time are needed only at the critical fre-
quency.
The R&S FSW EMI measurement also allows you to use multiple detectors for the final
measurement. The advantage of multiple detection is that you only need one test run
to see if the results comply with the limits specified in a standard. The detectors for the
final EMI tests are defined in the marker configuration (as opposed to the
trace detec-
tor which is used for the initial peak search).
The results of the final measurement are shown in the Result Summary (see chap-
ter 5.13.2, "EMI Measurement Results" , on page 289).
Defining a Dwell Time for the Final Measurement
EMC tests often require a specific dwell time for an EMI measurement. The dwell time
defines how long the R&S FSW measures the signal at the frequencies of the marker
positions. The dwell time is identical for all EMI final measurements and is thus defined
in the EMI measurement configuration. Select a dwell time according to the character-
istics of the measured signal. See also
chapter 5.13.3.2, "Detectors and Dwell Time" ,
on page 291.
5.13.3.8 Limit Checks
General limit line functionality is provided by the R&S FSW base unit. The base unit
also provides various predefined limit lines that you can use for various applications.
The R&S
FSW EMI measurement adds further predefined limit lines designed in com-
pliance with several EMC standards.
When using limit lines in combination with EMI measurements, the marker levels from
the initial measurement are compared to the limit line values. The result of the limit line
check is displayed in the diagram as usual.
In the EMI Result Summary, the limit check is based on the results of the final test.
Since the marker may be determined using a different detector than the final test
results, the two limit check results may differ. The difference between the limit line and
the measured value is colored to indicate the following states:
●
green : does not exceed limit
●
yellow : within margin
●
red : exceeds limit
For more information on using limit lines see chapter 7.5.2, "Basics on Limit Lines" ,
on page 524.
Electromagnetic Interference (EMI) Measurement (R&S FSW-K54)