How does the amplitude modulation setting in the Waveform Generator affect the output amplitude?
Written by Laura Becerra
Updated at July 2nd, 2025
-
Moku:Go
Moku:Go General Moku:Go Arbitrary Waveform Generator Moku:Go Data Logger Moku:Go Digital Filter Box Moku:Go FIR Filter Builder Moku:Go Frequency Response Analyzer Moku:Go Logic Analyzer & Pattern Generator Moku:Go Oscilloscope & Voltmeter Moku:Go PID Controller Moku:Go Spectrum Analyzer Moku:Go Waveform Generator Moku:Go Power Supplies Moku:Go Lock-in Amplifier Moku:Go Time & Frequency Analyzer Moku:Go Laser Lock Box Moku:Go Phasemeter
-
Moku:Lab
Moku:Lab General Moku:Lab Arbitrary Waveform Generator Moku:Lab Data Logger Moku:Lab Digital Filter Box Moku:Lab FIR Filter Builder Moku:Lab Frequency Response Analyzer Moku:Lab Laser Lock Box Moku:Lab Lock-in Amplifier Moku:Lab Oscilloscope Moku:Lab Phasemeter Moku:Lab PID Controller Moku:Lab Spectrum Analyzer Moku:Lab Time & Frequency Analyzer Moku:Lab Waveform Generator Moku:Lab Logic Analyzer/Pattern Generator
-
Moku:Pro
Moku:Pro General Moku:Pro Arbitrary Waveform Generator Moku:Pro Data Logger Moku:Pro Frequency Response Analyzer Moku:Pro Oscilloscope Moku:Pro PID Controller Moku:Pro Spectrum Analyzer Moku:Pro Waveform Generator Moku:Pro Lock-in Amplifier Moku:Pro Laser Lock Box Moku:Pro Digital Filter Box Moku:Pro FIR Filter Builder Moku:Pro Phasemeter Moku:Pro Multi-instrument Mode Moku:Pro Logic Analyzer/Pattern Generator Moku:Pro Time & Frequency Analyzer
- Python API
- MATLAB API
- Arbitrary Waveform Generator
- Data Logger
- Digital Filter Box
- FIR Filter Builder
- Frequency Response Analyzer
- Laser Lock Box
- Lock-in Amplifier
- Oscilloscope
- Phasemeter
- PID Controller
- Spectrum Analyzer
- Time & Frequency Analyzer
- Waveform Generator
- Logic Analyzer & Pattern Generator
- Multi Instrument Mode
- Moku Cloud Compile
- Moku general
- LabVIEW
The Waveform Generator can be set to modulate the output signal amplitude using an internal sinusoid or an external signal.
When using an internal sinusoid, a percentage setting is used to set modulation depth. The modulation percentage corresponds to the top and bottom edges of the waveform alternating between +/- the percentage of the amplitude.
For example, if we have a 1 Vpp sine wave it has an amplitude of 500 mV, as shown by the blue trace in the screenshot below. The red trace shows the same waveform with 50% amplitude modulation.
We expect the 500 mV to fluctuate between +/- 50% of 500 mV, meaning the amplitude should fluctuate between 250 mV (500 mV - 250 mV) and 750 mV (500 mV + 250 mV). The same concept applies to the negative portion of the waveform.
When using an external signal, modulation depth is in units of %/V.
Assume we have a 1 Vpp sinusoid sent into a waveform generator as a modulation source as shown in the screenshots below. The modulation depth is set to 50%/V.
The blue trace shows the 1 kHz waveform without modulation. The red trace shows the amplitude-modulated waveform, with its amplitude fluctuating between 375 mV and 625 mV. When the modulation source is at its peak, it's amplitude is 500 mV. If we multiply 0.5 V by 50%/V, we get 25%. 25% of 500 mV is 125 mV. Therefore, the amplitude modulated waveform fluctuates between (500 mV + 125 mV) and (500 mV - 125 mV).
