R&S FSW Series, Руководство пользователя

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Measurements and Results
R&S
®
FSW
247 User Manual 1173.9411.02 ─ 43
Fast SEM not supported for multiple sub blocks
For SEM with multiple sub blocks, fast SEM is not available. If more than one sub
block is defined and a standard is loaded which contains an active fast SEM setting,
this setting is disabled.
Absolute vs relative frequencies
In the default configuration with only one sub block, frequencies are defined relative to
the center frequency; this is the familiar configuration.
For setups with more than one sub block, frequencies are defined relative to the center
frequency of the reference ranges for the individual sub blocks. However, in the result
summary, frequencies are indicated as absolute values. Relative frequencies that refer
to different reference ranges would be inconvenient and difficult to analyze.
Limit check behavior for overlapping masks
Since spectrum emission masks are defined individually for each sub block, and sub
blocks can overlap, the question arises what happens during the limit check in the
overlapping regions? To answer this question, we must distinguish the following cases:
●
For the reference range, no limit checking is performed, as the reference range
contains the carrier
●
For other ranges, only the limit lines defined for ranges between the carriers, that is
the reference ranges to either side, are significant. In other words: if a limit line def-
inition covers the frequency area of several carriers, only the limit lines for ranges
between the corresponding reference range and the next closest reference range
are significant.
Figure 7-46: Behavior for overlapping masks
●
For the ranges in which multiple limit lines are significant, a range-specific function
determines the behavior of the limit check
Limit calculation for individual ranges
For each range a function can be defined that determines the behavior of the limit
check if there are multiple limit lines:
●
"NONE" : In reference ranges no limit check is performed;
Reference ranges always use the function "NONE".
For other ranges, see the combinations for overlapping ranges below.
●
"SUM" : sum of the two limit lines (calculated for linear powers) is used
●
"MAX" : maximum of the two limit lines is used
Spectrum Emission Mask (SEM) Measurement