TFG2900A Series Function/Arbitrary Waveform Generator Users’ Guide
Suin Instruments Co., Ltd
32
Type
〗
to display modulation type menu, press
〖
AM
〗
, modulation type will be AM, and display the
waveform’s diagram of amplitude modulation and it’s menu.
3.4.2 Carrier setting
: Usually Sine will be used as carrier. Of course other built-in waveforms can
also be used, but some are not suitable. Press
【
CH1
】
to enter carrier parameter interface to set
carrier’s parameter. Press
【
Modulate
】
again to enter modulation parameter setting interface to set
its parameter.
3.4.3 Modulation depth
: Press
〖
Depth
〗
to set modulation depth. It means the percent of carrier
amplitude variation quantity to amplitude setting value when modulation signal reaches the full
amplitude during AM process. After modulation, carrier envelope’s maximum amplitude(Amax),
minimum amplitude(Amin), amplitude setting (A), modulation depth(M), the four relationship is
as following formula:
Amax=(1+M)*A/2.2 Amin=(1-M)*A/2.2
Modulation depth can be derived from the two formulas above.
M=(Amax-Amin)*1.1/A
If modulation depth is 120%, Amax=A, Amin=-0.09A.
If modulation depth is 100%, Amax=0.909A, Amin=0.
If modulation depth is 50%, Amax=0.682A, Amin=0.227A.
If modulation depth is 0%, Amax=0.4545A, Amin=0.4545A.
That’s to say, when modulation depth is 0, carrier amplitude is almost half of amplitude setting
value.
3.4.4 Modulation frequency
: Press
〖
ModFreq
〗
to set modulation signal’s frequency value.
Modulation frequency is usually far lower than carrier frequency.
3.4.5 Modulation waveform
: Most of built-in waveform could be used as modulation waveform,
but some of them may be not suitable. Press
〖
Shape
〗
to choose modulation signal’s wave. After
selecting, press
〖
Back
〗
to return to modulation menu.
3.4.6 Modulation source
: Press
〖
Source
〗
to choose modulation source. If ‘Internal’ is chosen,
instrument will use internal modulation source, modulation frequency and waveform setting is
effective. If ‘External’ is chosen, instrument will use external modulation source, modulation
frequency and waveform setting will be ignored. Input modulation signal from rear panel’s present