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BW
not actually in-circuit when the average detector is on. If the detector is Average, and the span is zero,
use 10.0, which gives optimal behavior for Interval Markers in zero span.
5. Otherwise, if the detector is EMI Average, Quasi Peak or CISPR RMS, use 1.0. In fact this is a “don’t
care” since no VBW is used for these detectors, as noted under “Dependencies” for the VBW key.
6. Otherwise, the detector is simply
Peak or Sample. These two detectors can use the same rules. In
these cases, if any active trace is in max hold or min hold, use 10.0, because Max and Min Hold
operations are usually intended to capture peaks and pits without smoothing from the VBW filter;
otherwise, use 1.0 as a compromise, because you have not set the test set in a way that implies that
you are measuring noise, pulsed-RF or CW signals.
Note that because the above couplings depend on which traces are active, they are re-examined
whenever any trace goes active or inactive, except when this leaves no traces active. Transitioning to the
state where no traces are active should not affect the couplings; in that way, the annotation will always
reflect the state of the last trace which was active.
Span:3dB RBW
Selects the ratio between span and resolution bandwidth.
Normally, Span:3dB RBW (Auto) selects a Span:3dB RBW ratio of 106:1. If you manually enter the
ratio, Man becomes underlined, which enables you to manually select ratios more suitable for certain
measurements.
When the Span:3dB RBW is manually selected, it may be returned to the coupled state by pressing the
Span:3dB RBW key until
Auto is underlined. This may also be done by pressing Auto Couple or by
performing a
Preset.
Key Path BW
Remote Command [:SENSe]:FREQuency:SPAN:BANDwidth[:RESolution]:RATio
<integer>
[:SENSe]:FREQuency:SPAN:BANDwidth[:RESolution]:RATio?
[:SENSe]:FREQuency:SPAN:BANDwidth[:RESolution]:RATio:AU
TO OFF|ON|0|1
[:SENSe]:FREQuency:SPAN:BANDwidth[:RESolution]:RATio:AU
TO?
Example FREQ:SPAN:BAND:RAT 200 sets a ratio of 200:1, and turns off the auto
coupling.
FREQ:SPAN:BAND:RAT:AUTO ON
FREQ:SPAN:BAND:RAT?
Notes The values shown in this table reflect the conditions after a Mode Preset.
Dependencies Grayed out when the EMC Standard is set to CISPR or MIL, since RBW is
coupled to Center Frequency rather than Span in this case.
If the grayed out key is pressed, an advisory message is generated. If the
equivalent SCPI command is sent, the command is acted upon, but it doesn’t
affect the current measurement.