Modulation and Sweeps
2-15
AMPLITUDE MODULATION
Introduction
The DS345 has the ability to amplitude modulate its function output with both
the internal modulation generator and an external analog voltage. The inter-
nal modulation generator may modulate the output with a sine, square (pulse
modulation), triangle, ramp, or arbitrary modulation pattern. The external
modulation may be either simple AM or Double Sideband Suppressed Carri-
er (DSBSC) modulation.
External AM Source
The rear-panel AM INPUT is active at
all
times (even in concert with any oth-
er modulation type). The AM INPUT has an input voltage range of ±5V. A
+5V input produces an output that is 100% of the programmed value, a 0V
input turns the output will off (0%), and at -5V input produces an output that
is -100% of the programmed output (a 180° phase change). Applying voltag-
es from 0 to 5V will result in simple AM. If the voltages are balanced around
zero (from -5V to +5V) DSBSC modulation will result (for good carrier sup-
pression the modulating signal must have an average value of zero). The AM
INPUT has a bandwidth of about 20 kHz.
INTERNAL AM
The internal modulation generator can modulate any of the DS345's output
functions except NOISE. The modulating waveform may be a sine, square,
triangle, ramp, or arbitrary pattern. The rear-panel MODULATION OUTPUT
outputs a signal corresponding to the amplitude control voltage. 100% of the
output amplitude will produce an output of +5V, zero output will produce 0V,
and -100% output will produce -5V out.
Modulation Depth
Press [DEPTH] to display and set to the AM modulation depth. The value
may be set using the keypad and % units key, or the MODIFY keys. This val-
ue has a range of ±100% with 1% resolution. Positive values (0 to100%) will
set simple AM with a modulation percentage equal to the DEPTH. Zero per-
cent depth corresponds to no modulation, while 100% depth corresponds to
modulating the output from full off to full on. Negative values (-1% to
-100%
)
will set DSBSC modulation with a modulation percentage equal to the depth.
Modulation Rate
Press [RATE] to display and to set the frequency of the modulating function.
The frequency may be set with two digits of resolution from 0.001 Hz to
10 kHz
.
Содержание DS345
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Страница 5: ...DS345 Synthesized Function Generator iii...
Страница 20: ...Introduction 2 4...
Страница 64: ...Programming Commands 3 14...
Страница 72: ...Program Examples 3 22...
Страница 78: ...Troubleshooting 4 6...
Страница 82: ...Performance Tests 5 4...
Страница 101: ...Calibration 6 10...
Страница 109: ...Arbitrary Waveform Composer 7 8...
Страница 117: ...DS345 Circuitry 8 8...