3 Spectrum Analyzer Mode
3.2 Swept SA Measurement
When a CISPR or MIL EMI Standard is in use, Res BW is coupled to "Center Frequency" on page 281
and not to "Span" on page 287, and this is true even in Zero Span
Preset Auto (unless noted in the table below)
State Saved Saved in instrument state
Min 1 Hz
Max 8MHz is the max equivalent –3dB RBW, which means that the named RBW can actually exceed
8MHz if using a filter other than –3dB Gaussian
When Option FS1 or FS2 is installed and the filter type is Gaussian, the max RBW is 10MHz
For VXT, max -3dB RBW is limited to the current span or 8MHz, whichever is smaller
Annotation In the lower left corner of the screen, “RBW <(type)> <value>” will indicate the current setting of
resolution bandwidth where <(type)> summarizes the filter type and bandwidth. <(type)> is not
displayed for the –3 dB Filter Type
A “#” mark appears before “RBW” in the annotation when it is switched from Auto to Manual coupling.
Note that this # does NOT appear when in zero span with an EMC standard of None, as then there is
neither an autocoupled nor a manual state in zero span; there is no coupling at all
Backwards
Compatibility
Notes
For backwards compatibility this command obeys both the BANDwidth and BWIDth forms
Auto Function
Remote
Command
[:SENSe]:BANDwidth|BWIDth[:RESolution]:AUTO OFF | ON | 0 | 1
[:SENSe]:BANDwidth|BWIDth[:RESolution]:AUTO?
Example
:BWID:AUTO ON
:BWID:AUTO?
Preset
ON
More Information
When Res BW is set to Auto, the bandwidth selected depends on "RBW Filter Type"
on page 254
Only certain discrete resolution bandwidths are available. The available bandwidths
depend on RBW Filter Type or EMC Standard. If an unavailable bandwidth is entered
with the numeric keypad, the closest available bandwidth is selected.
The zero-span case in the Swept SA measurement deserves some mention, because
Res BW is coupled to Span when in a swept (non-zero) span and in zero span there
is normally no meaningful Res BW coupling. However, when a MIL or CISPR EMC
Standard is selected, there is a meaningful coupling for Res BW in Zero Span – in
fact, it is coupled to Center Frequency, to make measurements according to the EMI
specifications.
248 Spectrum Analyzer Mode User's &Programmer's Reference
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