A step attenuator between
the input connector and first mixer of a
spectrum analyzer. Also called the RF
attenuator. The input attenuator is used
to adjust level of the signal incident upon
the first mixer. The attenuator is used to
prevent gain compression due to high-level
or broadband signals and to set dynamic
range by controlling the degree of internally
generated distortion. In some analyzers,
the vertical position of displayed signals is
changed when the input attenuator setting
is changed, so the reference level is also
changed accordingly. In modern Agilent analyzers,
the IF gain is changed to compensate
for input attenuator changes, so signals
remain stationary on the display, and the
reference level is not changed