Before manual control can be used,
manual
must be selected on the
SWEEP TYPE
screen,
see above; if
manual
has not been set, the message
manual sweep mode not
selected
will be displayed before the menu is shown.
In manual mode the frequency can be stepped through the sweep range, defined on the
SWEEP
RANGE
screen, using the rotary control. Clockwise rotation sweeps the frequency up and
anticlockwise sweeps the frequency down; the
direction
setting on the
SWEEP TYPE
screen is ignored in Manual Sweep mode. The resolution of the frequency steps is set by the
res
olution soft-key. With
res:
coarse
the sweep range is divided into 100 increments for
the purposes of manual stepping;
medium
splits it into 1000 steps and
fine
splits it into
10,000 steps. Each complete turn of the rotary knob corresponds to 36 steps; turning the rotary
control rapidly will cause the frequency to jump by more than one step.
The frequency stepping resolution can be changed during a manual sweep such that
coarse
resolution can be used to quickly find a frequency of interest and
fine
resolution then selected
to step the frequency in smaller increments.
If
wrap
is set
on
the sweep wraps
−
round from
start
frequency to
stop
frequency and
vice
−
versa; if
wrap
is set
off
the sweep finishes at either the
start
or
stop
frequency
depending on the direction of the rotary control.
Sweep Spacing
Pressing the
spacing
...
soft
−
key on the
SWEEP SETUP
screen calls the
SWEEP
SPACING
screen.
SWEEP SPACING off
◊
♦
logarithmic
◊
linear
done
◊
With
linear
selected the sweep changes the frequency at a linear rate; with
logarithmic
selected the sweep spends an equal time in each frequency decade.
Sweep Marker
Pressing the
marker
...
soft
−
key on the
SWEEP SETUP
screen calls the
MARKER FREQ
screen.
MARKER FREQ off
◊
program:10·0000 MHz
done
◊
When set to
sweep sync
AUX OUT will additionally output a marker pulse if the marker
frequency is set within the sweep frequency range. The marker pulse is approximately 25% of the
amplitude of the sweep sync pulse.
A new marker frequency can be programmed directly from the keyboard or by using the rotary
control and cursor keys. The marker can be programmed to be any frequency within the sweep
range but the actual frequency will be that of the nearest ‘minor’ step, see Principles of Operation
section for an explanation of major and minor frequency steps. The minimum marker duration is
100us (1 minor step) but for longer sweeps the marker duration is increased (in 100us
increments) such that is never less than 1/250th of the complete sweep in order to keep the
marker visible if the whole sweep is displayed on an oscilloscope. Thus for a sweep time of
100ms the marker duration would be 400us. The first 100us increment represents the closest
frequency step to the programmed marker value.
The marker will not show if it is programmed to a frequency outside of the sweep range.
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