3-8
SWEEP FREQUENCY
OPERATION
The sweep generator can generate broad (full range) and narrow band
sweeps across the frequency range of the instrument. The 681XXB has
three sweep frequency modes—analog sweep, step sweep, and manual
sweep. The following paragraphs describe how to select each sweep fre-
quency mode, a sweep range, an output power level, a sweep trigger,
and frequency markers. Use the Analog Sweep, Step Sweep, and Man-
ual Sweep Frequency Mode menu maps (Chapter 4, Figures 4-3, 4-4,
and 4-5) to follow the menu sequences.
Selecting
Analog
Sweep Mode
In analog sweep frequency mode, the sweep gener-
ator’s output frequency is swept between selected
start and stop frequencies. When the sweep width is
>100 MHz, the sweep is phase-lock corrected at
both the start and stop frequencies and at each
band-switch point. When the sweep width is
≤
100 MHz, only the center frequency of the sweep is
phase-lock corrected.
To place the 681XXB in analog sweep frequency
mode, press the main menu key
CW/SWEEP
SELECT
At the resulting menu display, press
Analog
. The
Analog Sweep Menu (below) is then displayed.
This menu lets you perform the following:
Select a sweep range (edit the sweep start and
stop frequency parameters).
Go to the sweep ramp menu (set the sweep
time and select a sweep trigger).
Select an output power level for the sweep.
Go to the alternate sweep menu.
LOCAL (FRONT
SWEEP FREQUENCY
PANEL) OPERATION
OPERATION
NOTE
In 681X5B models performing ana-
log sweeps between 0.5 and
2.2 GHz, the sweep is phase-lock
corrected as follows. For sweep
widths of >25 MHz, phase-lock cor-
rection occurs at both the start and
stop frequencies and at each band-
switch point. For sweep widths of
≤
25 MHz, only the center frequency
of the sweep is phase-lock corrected.
681XXB OM
3-23
