Amplitude Modulation (Am) - PeakTech 4055 MV Bedienungsanleitung

4.7. Amplitude modulation (AM)

In AM, the amplitude of the carrier is varied by the instantaneous voltage of the modulating waveform, all
the 16 waveforms could be used as carrier waveform, of course, it is invalid to use DC or noise. Before
entering into amplitude modulation, users should firstly set the waveform, frequency and amplitude of
carrier wave under continuity function.
Press【AM】key, the keyboard light of "AM" will be on and the generator enters into amplitude
modulation function.
4.7.1. Modulation frequency:
Press【Menu】key to light "Mod_f" character, and then set modulation frequency value. In AM,
modulation frequency is usually far lower than carrier frequency.
4.7.2. Modulation depth:
Press【Menu】key to light "Depth" character, and then set modulation depth value. Modulation depth
represents the percentage of variation of the carrier amplitude to the amplitude setting value while the
modulating wave is with full amplitude during AM process. If the maximum amplitude of the modulated
waveform is called as Amax, the minimum amplitude as Amin, the amplitude setting value as A, the
modulation depth as M, then the relationship between the four values is:
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=0.455A, Amin=0.455A.
That is to say, when modulation depth is 0, carrier amplitude is half of the amplitude setting.
4.7.3. Modulation waveform:
Press【Menu】key to light "Shape" character, the current modulation waveform sequence No. is shown,
input modulation waveform No. with the numeric keys or adjusting knob to select modulation waveform,
the modulation waveform may be any one of the 16 kinds of waveforms listed in the waveforms table in
section 4.2.9.
4.7.4. Sync output:
In AM, 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 is equal to modulating frequency and its phase is
referenced to the phase of the modulating signal.
In AM, press【AM】key again, the "AM" light will be off, and the generator exits AM function and returns
back to continuity function.
Amax ＝ (1 + M) x A ÷ 2.2
Then the modulation depth is M ＝ (Amax - Amin) x 1.1÷A
Amin ＝ (1 - M) x A ÷ 2.2
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