The analyzer has fully variable RBW between 300Hz
and 10MHz in settable a 1:3:10 sequence, or can be set to Auto where it
sets to an appropriate value for the current span.
VBW can be similarly set over the same range. VBW tracking sets the VBW
to be equal to the RBW or offset upwards or downwards by an amount
settable by the Track Offset key.