78 Chapter 2 
Front-Panel Key Reference
BW/Avg
BW/Avg
Activates the resolution bandwidth function and accesses the menu 
keys that control the bandwidth functions and averaging.
Res BW
Auto Man
Changes the 3 dB resolution bandwidth on the analyzer from 1 kHz to 
5 MHz in a 1, 3, 10 sequence using the knob or step keys. If an 
unavailable bandwidth is entered using the numeric keypad, the closest 
available bandwidth in the 1, 3, 10 sequence is used. (Option 1DR 
provides additional 300 Hz, 200 Hz, 100 Hz, 30 Hz and 10 Hz 
bandwidths. For firmware revision A.08.00 and later, the bandwidth 
range is from 1 Hz to 5 MHz if you have both Options 1D5 and 1DR.) As 
the resolution bandwidth is decreased, the sweep time is modified to 
maintain amplitude calibration. Resolution bandwidth is also related to 
span. As span is decreased, the resolution bandwidth is decreased. As 
the resolution bandwidth changes, the video bandwidth, if in auto 
couple mode, changes to maintain the VBW/RBW ratio. 
NOTE With firmware A.08.00 and greater, 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 display when it is not 
coupled. To recouple the resolution bandwidth, press 
Res BW (Auto) (or 
press 
Auto Couple, Auto All). The resolution bandwidth can be changed 
using the step keys, the knob, or the numeric keypad. 
Key Access: 
BW/Avg
Video BW 
Auto Man
Changes the analyzer post-detection filter from 30 Hz to 3 MHz in a 1, 
3, 10 sequence using the knob, step keys, or the numeric keypad. If an 
unavailable bandwidth is entered using the numeric keypad, the closest 
available bandwidth in the 1, 3, 10 sequence is used. (Option 1DR 
provides additional 1 Hz, 3 Hz and 10 Hz video bandwidths when the 
resolution bandwidth is ≤ 300 Hz.) 
As the video bandwidth is decreased, the sweep time is increased to 
maintain amplitude calibration. A “#” mark appears next to VBW on 
the bottom of the analyzer display when it is not coupled. To couple the 
video bandwidth, press 
Video BW (Auto) (or press Auto All).
Key Access: 
BW/Avg