Sweep Type
Pressing the
type
soft-key calls the
SWEEP TYPE
screen.
SWEEP TYPE:
continuous
◊
direction: up
◊
sync: on done
◊
This screen is used to set the sweep mode (continuous; triggered; triggered, hold and reset;
manual) and sweep direction.
Alternate presses of the
direction
soft-key change the sweep direction from
up
,
i.e. start
frequency to stop frequency, to
down
,
i.e. from stop frequency to start frequency. In the sweep
mode descriptions which follow the direction is assumed to be
up
, i.e. start to stop; all modes
can also be used with the direction set to
down
.
In
continuous
mode the generator sweeps continuously between the start and stop
frequencies, triggered repetitively by an internal trigger generator whose frequency is determined
by the sweep time setting. At the stop frequency the generator resets to the start frequency after
a delay long enough for an oscilloscope to retrace, for example, and begins a new sweep. If
sync
is set to
on
(the default) the generator actually steps from the stop frequency to zero
frequency and then starts the next sweep from the first point of the waveform, synchronised to the
(internally generated) trigger signal.
This is useful because the sweep always starts from the same point in the waveform but the
waveform discontinuity can be undesirable in some circumstances, e.g. filter evaluation. With
sync
set to
off
, the frequency steps directly and phase continuously from the stop frequency
to the start frequency but is not synchronised to the software-generated trigger signal.
In
triggered
mode the generator holds the output at the start frequency until it recognises a
trigger. When triggered, the frequency sweeps to the stop frequency, resets, and awaits the next
trigger. If
sync
if set to
on
the frequency resets to zero frequency (i.e. no waveform) and
starts a new sweep at the first point of the waveform when the next trigger is recognised. If
sync
is set to
off
the waveform resets to the start frequency and runs at that frequency until the next
trigger initiates a new sweep.
In
trig’d, hold/reset
mode the generator holds the output at the start frequency until it
recognises a trigger; when triggered, the frequency sweeps to the stop frequency and holds. At
the next trigger the output is reset to the start frequency where it is held until the next sweep is
initiated by a further trigger. If
sync
is set to
off
the output operates exactly as described
above; if
sync
is set to
on
the frequency actual goes to zero at the start and begins each new
sweep at the first point of the waveform.
For both
Triggered
and
Trig’d, hold/reset
modes the TRIG IN input is automatically
set to external. The trigger source can be an external signal applied to TRIG IN (positive edge
triggers), pressing the MAN/SYNC key on the front panel, or a remote command.
In
manual
mode the whole sweep process is controlled from the
MANUAL SWEEP
screen.
Manual Sweep
Pressing the
manual…
soft-key on the
SWEEP SETUP
screen calls the
MANUAL SWEEP
FREQ
screen.
MANUAL SWEEP FREQ:
1·630 MHz
◊
step fast wrap
◊
♦
step slow done
◊
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