The current resolution bandwidth value is displayed in this submenu key. The key displays the Zero Span RBW if Zero Span is selected. The RBW can be changed using the keypad, the arrow keys, or the rotary knob. Bandwidth values increment in a 1 to 3 sequence, from 1 Hz to 3 Hz to 10 Hz, or from 10 Hz to 30 Hz to 100 Hz, for example. Refer to your instrument Technical Data Sheet for the resolution bandwidth range.

Toggles between Linear averaging (arithmetic mean) and Logarithmic averaging (geometric mean). When VBW linear averaging is used, the result is calculated by Linear running average, then Log, and then displayed. When VBW log averaging is used, the result is obtained by taking Log, then running average, and then displayed. These two approaches can result in different responses to time-varying signals.

This submenu key displays the ratio between the span width and the resolution bandwidth. The default value is 100, meaning that the span width is approximately 100 times the resolution bandwidth. The value is approximate because resolution bandwidth filters come in discrete steps while span width can be set to any value up to the limit of the instrument. To change the ratio, press this submenu key and use the keypad, the arrow keys, or the rotary knob to select a new ratio.