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7.11.1 Carrier setting:
Press
〖
CarrFreq
〗
softkey to select “carrier frequency” or “carrier amplitude ”. It is able to set carrier
frequency and amplitude at any moment while the PWM signal is outputted.
7.11.2 Modulating waveform frequency:
In amplitude modulation, the modulating frequency is always much lower than the carrier frequency. If
internal modulating signal is used, you can set the modulating frequency within the range of 2mHz
~
20kHz.
If external modulating signal is used, the modulating frequency setting is ignored.
7.11.3 Modulation depth:
It represents maximum variation in the pulse of the carrier in pulse width modulation.
7.11.4 Modulating waveform:
It is able to set modulating waveform shape if internal modulating signal is used. Press
〖
SineModu
〗
softkey to select “sine modulation”, “square modulation”, “triangle modulation” or “ramp modulation”.
Modulating waveform shape setting would be ignored if external modulating signal is used.
7.11.5 Modulating source:
The function generator will accept an internal or external modulation source for AM. Press
〖
Int Modu
〗
softkey to select “external source”. The modulating signal is inputted from the rear panel “Modulation In”
connector for AM. If the amplitude of the external modulating signal is ±5V, the modulation depth setting and
the display value accord with the real modulation depth. Otherwise, the modulation depth setting and display
value are not accurate.
3.13.6 Sync output:
In PWM, the generator outputs a sync signal from the front panel “Sync” connector, which is square wave
with TTL level and 50% duty cycle, its frequency if equal to modulating frequency and its phase is
referenced to the phase of the modulating signal.
7.12 To set the pulse width modulation (PWM) (only P 4050)
In PWM, the carrier signal only can adopt pulse waveform and the pulse width is varied by the instantaneous
voltage of the modulating waveform. Follow the steps to set a PWM waveform with 2 kHz carrier frequency,
1 Hz modulating frequency and 50% modulation depth.
PWM select pulse waveform automatically:
7.12.1
Press
【
Mod
】
key to enter the interface of modulating output and select modulating mode.
7.12.2
Press
〖
PWM
〗
softkey to enter the interface of PWM modulate and “PWM by Sine” is displayed on
the upper-left of screen.
7.12.3
The current selected option is “carrier frequency”; use numeric keys or knob to set carrier frequency
to 2 kHz.
7.12.4
Press
〖
Modu Freq
〗
softkey to select “modulate frequency” and set it to 1 Hz by using numeric keys
or knob.
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