ARBITRARY FREQUENCY
30·00 MHz
♦
sample waveform
◊
♦
freq period
◊
Frequency can be set in terms of frequency or period as before by pressing the
freq
or
period
soft-key respectively. Note that the frequency and period resolution in arbitrary mode is
only 4 digits because Clock Synthesis generation is used, see Principles of Operation section.
Additionally, for arbitrary waveforms, frequency/period can be set in terms of the sample clock
frequency, by pressing the
sample
soft-key, or in terms of the waveform frequency, by pressing
the
waveform
soft-key. The relationship between them is
waveform frequency = sample frequency ÷ waveform size.
Frequency/period entries are made direct from the keyboard or by using the rotary control in the
usual way.
Pressing the FREQuency key with Sequence selected calls the
SEQ CLOCK FREQUENCY
screen:
SEQ CLOCK FREQUENCY
30·00 MHz
♦
freq period
◊
Frequency/period can now
only
be set in terms of the clock frequency. Frequency/period entries
are made direct from the keyboard or by using the rotary control in the usual way.
Amplitude
Pressing the AMPLitude key with an arbitrary waveform selected calls the
AMPLITUDE
screen.
AMPLITUDE:
+20·0 Vpp
♦
Vpp
load:hiZ
◊
This differs from the
AMPLITUDE
screen for standard waveforms in that amplitude can now only
be entered in volts peak-to-peak.
Note that the peak-to-peak amplitude set will only actually be output if the arbitrary waveform has
addresses with values which reach -2048 and +2047; if the maximum value range is -1024 to
+1023 for example then the maximum peak-to-peak voltage will only be 10Vpp for the instrument
set to 20Vpp.
Sync Out Settings with Arbitrary Waveforms
The default setting for Sync Out when arbitrary waveforms are selected is
waveform sync
; this
is a pulse that starts coincident with the first point of the waveform and is a few points wide.
If a waveform sequence has been selected then Sync Out defaults to
sequence sync
;
this is a
waveform which goes low during the last cycle of the last waveform in a sequence and is high at
all other times. When sequence is used in Triggered Burst mode, the default and only source
clk
for
burst count
on the
TRIGGER SETUP
screen becomes
sequence sync
regardless of
whether the display shows
waveform sync
or
pos’n marker
.
Sync Out can additionally be set to
pos’n marker
for arbitrary waveforms. If Triggered Burst
mode is used the source
clk
can also be set to count
pos’n markers
. Position markers can
be used in blocks to create a pulse waveform whose phase can be varied (by varying the point in
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