72 Chapter 2
Instrument Functions: A - L
BW/Avg
Instrument Functions: A - L
2.3.3 VBW/RBW
Selects the ratio between the video and resolution bandwidths. Video bandwidth wider
than resolution bandwidth (VBW/RBW ratio > 1.000), provides the best peak
measurements of signals such as wideband radar pulses. VBW narrower than RBW
(VBW/RBW ratio < 1.000) reduces the variance of noise-like signals and makes spectral
components close to the noise floor easier to view. The knob and step keys change the ratio
in a 1, 3, 10 sequence. Pressing
Preset or selecting Auto Couple, Auto All sets the ratio to
1.000 X. When
VBW/RBW (Auto) is selected, the ratio is determined as indicated below.
NOTE This key is grayed out when the Quasi Peak or EMI Average detector is
selected.
Key Path:
BW/Avg
Saved State: Saved in Instrument State
Factory Preset: Auto (1.0)
Range: 0.00001 to 3.0e6 (3,000,000)
Table 2-1 VBW/RBW Ratio Auto Rules
Detector Mode Noise
Marker
Ratio Notes
Peak On 10 Noise response is esitmated for wide VBW case
Negative Peak On 10 Don’t care
Average On 0.1 Narrow VBW for low-sigma marker readout
Normal On 0.1 Don’t care (noise marker makes is not valid with
normal detection.)
Sample On 0.1 Narrow VBW for low-sigma marker readout
Peak Off 10 Wide VBW for good impulse BW (pulsed RF)
Negative peak Off 10 Don’t care
Average Off 0.1 Narrow VBW for low-sigma trace results
Normal Off 1.0 Swept analysis CW signal setting
Sample Off 1.0 Wide VBW for good impulse BW (pulsed RF)
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