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Chapter 2 83
Instrument Functions: A - L
BW/Avg
Instrument Functions: A - L
2.2 BW/Avg
Activates the resolution bandwidth function, and displays the menu keys that control both
the bandwidth and averaging functions.
2.2.1 Res BW
Enables you to select the 3.01 dB resolution bandwidth (RBW) of the analyzer in 10% steps
from 1 Hz to 3 MHz, plus bandwidths of 4, 5, 6, or 8 MHz.
If an unavailable bandwidth is entered with the numeric keypad, the closest available
bandwidth is selected.
Sweep time is coupled to RBW. As the RBW changes, the sweep time (if set to
Auto)is
changed to maintain amplitude calibration.
Video bandwidth (VBW) is coupled to RBW. As the resolution bandwidth changes, the
video bandwidth (if set to
Auto) changes to maintain the ratio set by VBW/RBW.
WhenResBWissetto
Auto, resolution bandwidth is autocoupled to span. The ratio of span
to RBW is set by
Span/RBW (described on page 93). The factory default for this ratio is
approximately 106:1 when auto coupled. When Res BW is set to Man, bandwidths are
entered by the user, and these bandwidths are used regardless of other analyzer settings.
NOTE In zero span, the auto/manual function of this key is not applicable. When Res
BW (Auto)
is selected in non-zero span, any changes to Res BW while in zero
span will revert to the Auto value when you return to non-zero span. When
Res BW (Man) is selected in non-zero span, any changes to Res BW while in zero
span will be maintained when you return to non-zero span.
A # mark appears next to Res BW on the bottom of the analyzer display when it is not
coupled. To couple the resolution bandwidth, press
Res BW (Auto) or Auto All.
NOTE For applications that require 6 dB resolution bandwidths, it is possible to use
an equivalent 3 dB resolution bandwidth. Because the analyzer has Gaussian
RBW, the equivalent 6 dB bandwidth of any RBW filter can be determined
using the following formula: 6dBRBW= 3dBRBWx 1.414. For example, if a
6 dB RBW of 100 kHz is required, the equivalent 3 dB RBW Filter would be
100 kHz/1.414 = 70.7 kHz. The closest RBW filter for the analyzer that would
be used is 68 kHz.
Key Path:
BW/Avg
Saved State: Saved in Instrument State